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Systematic Review of High-Intensity Progressive Resistance Strength Training of the Lower Limb Compared With Other Intensities of Strength Training in Older Adults

Published:March 11, 2013DOI:https://doi.org/10.1016/j.apmr.2013.02.022

      Abstract

      Objective

      To examine the effect of high-intensity progressive resistance strength training (HIPRST) on strength, function, mood, quality of life, and adverse events compared with other intensities in older adults.

      Data Sources

      Online databases were searched from their inception to July 2012.

      Study Selection

      Randomized controlled trials of HIPRST of the lower limb compared with other intensities of progressive resistance strength training (PRST) in older adults (mean age ≥65y) were identified.

      Data Extraction

      Two reviewers independently completed quality assessment using the Physiotherapy Evidence Database (PEDro) scale and data extraction using a prepared checklist.

      Data Synthesis

      Twenty-one trials were included. Study quality was fair to moderate (PEDro scale range, 3–7). Studies had small sample sizes (18–84), and participants were generally healthy. Meta-analyses revealed HIPRST improved lower-limb strength greater than moderate- and low-intensity PRST (standardized mean difference [SMD]=.79; 95% confidence interval [CI], .40 to 1.17 and SMD=.83; 95% CI, −.02 to 1.68, respectively). Studies where groups performed equivalent training volumes resulted in similar improvements in leg strength, regardless of training intensity. Similar improvements were found across intensities for functional performance and disability. The effect of intensity of PRST on mood was inconsistent across studies. Adverse events were poorly reported, however, no correlation was found between training intensity and severity of adverse events.

      Conclusions

      HIPRST improves lower-limb strength more than lesser training intensities, although it may not be required to improve functional performance. Training volume is also an important variable. HIPRST appears to be a safe mode of exercise in older adults. Further research into its effects on older adults with chronic health conditions across the care continuum is required.

      Keywords

      List of abbreviations:

      CI (confidence interval), GDS (Geriatric Depression Scale), HIPRST (high-intensity progressive resistance strength training), LIPRST (low-intensity progressive resistance strength training), MIPRST (moderate-intensity progressive resistance strength training), 1RM (1 repetition maximum), PEDro (Physiotherapy Evidence Database), POMS (Profile of Mood States), PRST (progressive resistance strength training), QOL (quality of life), SMD (standardized mean difference), WMD (weighted mean difference)
      Loss of muscle mass and strength is common among older adults, with a strong association between reduced lower-limb function and dependence in activities of daily living.
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      Lower extremity function in persons over the age of 70 years as a predictor of subsequent disability.
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      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      Evidence demonstrates that exercise in older adults can minimize the effect of functional decline,
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Jones C.T.
      • Lowe A.J.
      • MacGregor L.
      • Brand C.A.
      Randomised controlled trial of an exercise intervention to reduce functional decline and health service utilisation in the hospitalised elderly.
      • Rosendahl E.
      • Gustafson Y.
      • Nordin E.
      • et al.
      A randomized controlled trial of fall prevention by a high-intensity functional exercise program for older people living in residential care facilities.
      • Rosendahl E.
      • Lindelof N.
      • Littbrand H.
      • et al.
      High-intensity functional exercise program and protein-enriched energy supplement for older persons dependent in activities of daily living: a randomised controlled trial.
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      Randomized controlled trial of exercise to improve outcomes of acute hospitalization in older adults.
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      with progressive resistance strength training (PRST) a commonly employed method. Progressive resistance strength training, where the resistance is progressed to maintain intensity,
      • Kraemer W.J.
      • Adams K.
      • Cafarelli E.
      • et al.
      The American College of Sports position stand. Progression models in resistance training for healthy adults.
      improves strength
      • Fiatarone M.
      • Marks E.
      • Ryan N.
      • Meredith C.
      • Lipsitz L.
      • Evans W.
      High-intensity strength training in nonagenarians: effects on skeletal muscle.
      and functional ability
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      and can eliminate the need for gait aids in older adults.
      • Fiatarone M.A.
      • O'Neill E.F.
      • Ryan N.D.
      • et al.
      Exercise training and nutritional supplementation for physical frailty in very elderly people.
      Moderate-intensity progressive resistance strength training (MIPRST) and high-intensity progressive resistance strength training (HIPRST) have also been shown to have a positive impact on depression and quality of life (QOL).
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      A previous meta-analysis suggests that HIPRST is better than lesser intensities for strength outcomes, however, may not be required for functional outcomes.
      • Steib S.
      • Schoene D.
      • Pfeifer K.
      Dose-response relationship of resistance training in older adults: a meta-analysis.
      Training volume may also be an important variable, because some trials have reported similar strength gains with low repetitions at high intensity and high repetitions at low intensity.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      The risks associated with HIPRST may be greater than for lower intensities, although the safety of HIPRST in this population is not well understood. At present there is no consensus regarding the optimal training intensity for achieving improvements in functional status, mood, and QOL while maintaining safety in older adults.
      Other reviews have examined PRST in older adults without examining the effect of intensity
      • Latham N.K.
      • Bennett D.A.
      • Stretton C.M.
      • Anderson C.S.
      Systematic review of progressive resistance strength training in older adults.
      or the effect of intensity on a wide variety of outcomes.
      • Steib S.
      • Schoene D.
      • Pfeifer K.
      Dose-response relationship of resistance training in older adults: a meta-analysis.
      This review was performed to summarize the evidence comparing high intensity to other intensities of PRST in older adults on a broader range of outcomes and to provide recommendations for clinical practice and future research. The primary aims were to examine the effectiveness of HIPRST in older adults in improving strength, endurance, and functional performance and assess its safety compared with other intensities of PRST. Secondary aims were to examine the effect of HIPRST on cognition, psychological status, QOL, falls rate, power, flexibility, and cardiovascular fitness in those who have undertaken such training.

      Methods

       Selection criteria

      Only published randomized controlled trials comparing HIPRST with other intensities of PRST were considered for inclusion.
      Studies with participants' mean age of ≥65 years were included, but excluded if any participants were aged <60 years old. Participants were untrained in PRST. There were no exclusions on the basis of health, sex, residence, or setting of therapy.
      There are no consistent criteria for maximal-, high-, moderate-, and low-intensity strength training in the literature.
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      • Spruit M.
      • Eterman R.
      • Hellwig V.
      • Janssen P.
      • Wouters E.
      • Uszko-Lencer N.
      Effects of moderate-to-high intensity resistance training in patients with chronic heart failure.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Jan M.H.
      • Lin J.J.
      • Liau J.J.
      • Lin Y.F.
      • Lin D.H.
      Investigation of clinical effects of high- and low-resistance training for patients with knee osteoarthritis: a randomized controlled trial.
      Percentage of 1 repetition maximum (1RM) is often used to specify intensity. This is the maximum weight a person can lift once only “before fatigue using good form and technique”
      American College of Sports Medicine Position Stand
      The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults.
      (p984) “performed primarily by the specified muscle groups without the use of momentum or any changes in body position, other than those directly resulting from the movement of the weight, during the exercise motion.”
      • Charette S.L.
      • McEvoy L.
      • Pyka G.
      • et al.
      Muscle hypertrophy response to resistance training in older women.
      (p1913) Although not specifically defined in a previous systematic review,
      • Latham N.K.
      • Bennett D.A.
      • Stretton C.M.
      • Anderson C.S.
      Systematic review of progressive resistance strength training in older adults.
      many studies with 70% to 90% 1RM were labeled as high intensity.
      • Rall L.C.
      • Roubenoff R.
      • Cannon J.G.
      • Abad L.W.
      • Dinarello C.A.
      • Meydani S.N.
      Effects of progressive resistance training on immune response in aging and chronic inflammation.
      • Flynn M.G.
      • Fahlman M.
      • Braun W.A.
      • et al.
      Effects of resistance training on selected indexes of immune function in elderly women.
      • Hagerman F.C.
      • Walsh S.J.
      • Staron R.S.
      • et al.
      Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular, and metabolic responses.
      Other articles have described moderate intensity as 50% to 70%
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      and low intensity as <50%.
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Singh N.A.
      • Clements K.M.
      • Fiatarone M.A.
      Randomized controlled trial of progressive resistance training in depressed elders.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      Therefore, for the purposes of this systematic review, HIPRST was defined as 70% to 89% of 1RM, maximal intensity was defined as ≥90% 1RM, MIPRST as 50% to 69% 1RM, and low-intensity progressive resistance training (LIPRST) as <50% 1RM.
      Studies were considered if the HIPRST program was land based and performed against any type of resistance within the above percentage 1RM ranges. All studies were required to have at least 1 control group who undertook another intensity of strength training: higher, lower, and/or variable. Trials of HIPRST of the lower limb with or without additional upper limb, trunk, or abdominal strengthening were considered. Trials were excluded if the high-intensity range was outside of the defined percentage 1RM; where the specified intensity was not defined as a percentage of 1RM; where HIPRST was combined with other types of exercise other than a warm-up and cool-down (eg, aerobic exercise); where training was performed at different velocities, such as power training at high velocities; or where the comparison group did not include a second intensity of training (a no training control group).
      Strength, endurance, gait speed, functional limitation, power, torque, flexibility, maximum oxygen consumption, cognition, psychological status, and QOL were analyzed as continuous variables. Falls and adverse events were reported as dichotomous outcomes. Relative training volumes were calculated (total repetitions × relative load as percentage 1RM
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      ) where they were not reported in studies. For each trial, these were reported as a percentage of the training volume undertaken by HIPRST group participants.

       Search strategy

      The following online databases were searched from the earliest date available until July 2012: the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, AMED, AgeLine, and the Physiotherapy Evidence Database (PEDro). Reference lists from relevant studies and review studies were hand searched for additional articles. No language restrictions were applied.
      Search terms (appendix 1) were used in the search strategy in MEDLINE and adapted for use in the other databases. These terms were limited to randomized controlled trials.

       Quality assessment and data extraction

      Data were extracted independently by 2 reviewers using a prepared checklist. Disagreements were resolved by consensus. Extraction from each trial included: (1) characteristics of trial participants (age, sex, and level of normative physical activity) and the trial’s inclusion and exclusion criteria; (2) HIPRST and comparison PRST program details (intensity, repetitions and sets, duration, frequency, number of lower-limb exercises, equipment used); and (3) type of outcome measure(s) and adverse events. Methodologic quality assessment was conducted independently by 2 reviewers (M.J.R. and R.E.B.T.) using the PEDro scale.
      • Maher C.G.
      • Sherrington C.
      • Herbert R.D.
      • Moseley A.M.
      • Elkins M.
      Reliability of the PEDro Scale for rating quality of randomized controlled trials.
      Disagreements were resolved by consensus. Where unclear, authors of included studies were approached via email and asked to provide details of missing data or clarification regarding methods.

       Data analysis

      Where studies were considered clinically homogeneous, data were pooled for meta-analyses using Review Manager 5.1 softwarea and weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated. A fixed or random effects model was used depending on assessment of heterogeneity. To enable comparison between continuous variables with different units, standardized mean differences (SMDs) with 95% CIs were calculated. Based on Cohen conventional definition for SMD, values of 0.2 were considered small, 0.5 was considered medium, and 0.8 was considered large.
      • Cohen J.
      Statistical power analysis for the behavioral sciences.
      To assess the effects of our definitions of intensity on the review outcomes, a sensitivity analysis was performed where only extreme values were included (high vs low intensity). Where sufficient data were available, a second sensitivity analysis examined whether the effects differed in higher-quality trials (PEDro ≥6) compared with lower-quality trials (PEDro ≤5).

      Results

      The search strategy returned a total of 912 citations. Details on study selection can be found in figure 1. Where a single randomized controlled trial resulted in ≥2 publications, each article was included if they investigated a separate outcome measure of interest. Eight of the included articles fell into this category.
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      Multiple articles are referenced as the first published article only. Twenty-one articles of 17 trials were eligible for inclusion (see fig 1), with a total of 830 enrolled participants and 724 participants’ data reported.
      Figure thumbnail gr1
      Fig 1Flowchart showing the selection of studies for this systematic review.
      Table 1 summarizes details from included trials. Eight trials (10 articles) investigated high- and moderate-intensity training only,
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      6 trials (7 articles) examined high- and low-intensity training only,
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      1 trial examined maximal-, high-, and moderate-intensity training,
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      1 trial (2 articles) examined high-, moderate-, and low-intensity training,
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      and 1 trial reported on high- versus a variable-intensity program.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      Some trials included upper limb and trunk PRST as part of their programs.
      Table 1Summary of 21 included studies
      StudyPEDro Score (/10)Age Range (mean)ParticipantsSample Size
      Number of enrolled participants.
      (final no.)
      No. of LL ExFrequency and Duration
      Total duration – some studies included a 1- to 4-wk conditioning period, which gradually increased %RM to the target level.
      High Intensity Resistance (%1RM), Sets × repsComparison Intensity: (%1RM) Sets × repsAdverse EventsOutcomes
      Outcomes of interest to this review.
      MaximalModerateLow/Other
      Beneka
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      660+(65)Healthy, sedentary64 (64)33×wk

      16wk
      70%

      3×8–10
      90%

      3×4–6
      50%

      3×12–14
      NANot reportedStrength
      Cassilhas
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      665–75Male, sedentary62 (62)23×wk

      24wk
      80%

      2×8
      NA50%

      2×8
      NANot reportedStrength, cognition, QOL, depression
      Fatouros, Kambas et al
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      5(71.2)Male, sedentary59 (52)33×wk

      24wk
      80%–85%

      2–3×6–8
      NA50%–55%

      2–3×14–16
      NAReported, no detailsStrength, power, functional performance, walking speed
      Fatouros, Tournis
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      565–78Male, sedentary, overweight57 (50)33×wk

      24wk
      80%–85%

      2–3×8
      NA60%–65%

      2–3×10
      45%–50%

      2–3×14
      Reported, no detailsStrength, cardiovascular fitness
      Fatouros
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      5As aboveStrength, flexibility
      Harris
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      461–85 (71.2)Healthy76 (62)32×wk

      18wk
      75%

      3×9

      84%

      4×6
      NA67%

      2×15
      NANilStrength
      Hortobagyi
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      566–83 (72)Healthy30
      Participants 60 years or older.
      (27)
      13×wk

      10wk
      80%

      5×4–6
      NANA40%

      5×8–12
      YesStrength
      Hunter
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      461–77 (>65)Healthy30 (28)23×wk

      25wk
      80%

      2×10
      NANAVariable: 50%, 65%, 80%Not reportedStrength, perceived exertion, functional performance, cardiovascular fitness
      Kalapotharakos
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      660–74Healthy, sedentary33 (33)23×wk

      12wk
      80%

      3×8
      NA60%

      3×15
      NANot reportedStrength
      Kalapotharakos
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      6As above35 (33)Not reportedStrength, functional performance, flexibility, walking speed
      Pruitt
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      465–79Female, healthy40 (26)53×wk

      52wk
      80%
      Includes 1–2wk of pretraining/orientation at reduced number of sets, reps, and/or intensity – 1 set only.


      2×7

      (warm up 40% 1×14)
      NANA40%

      3×14
      YesStrength
      Seynnes
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      473–95 (81.5)Institutionalized27 (22)13×wk

      10wk
      80%

      3×8
      NANA40%

      3×8
      NilStrength, endurance, 6MWT, disability
      Singh
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      660–85Older adults with depression60 (54)33×wk

      8wk
      80%

      3×8
      NANA20%

      3×8
      YesStrength, QOL, depression
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      565–93 (79.4)Recent functional decline29 (24)13×wk

      12wk
      80%
      Includes 1–2wk of pretraining/orientation at reduced number of sets, reps, and/or intensity – 1 set only.


      3×8
      NANA10%–20%

      3×8
      YesStrength, functional performance
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      765–93 (78.2)Recent functional decline71 (61)33×wk

      12wk
      80%
      Includes 1–2wk of pretraining/orientation at reduced number of sets, reps, and/or intensity – 1 set only.


      3×8
      NANA10%–20%

      3×8
      YesStrength, functional performance
      Taaffe
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      365–79Female, healthy36 (25)33×wk

      52wk
      80%

      2×7

      (warm up 40%

      1×14)
      NANA40%

      3×14
      Not reportedStrength
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      561–86 (68.6)Healthy, sedentary45 (42)23×wk

      12wk
      75%–85%

      2×8–10
      NA55%–65%

      2×14–16
      NANot reportedStrength, mood and anxiety, cognition, functional performance
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      660–86 (68.5)Female, healthy, sedentary36 (36)23×wk

      12wk
      75%–85%

      2×8–10
      NA55%–65%

      2×14–16
      NANot reportedStrength, psychological measures
      Vincent et al
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      460–83 (68.4)Healthy84 (62)63×wk

      26wk
      80%

      1×8
      NA50%

      1×13
      NAYesStrength, endurance
      Vincent et al
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women.
      As aboveCardiovascular fitness
      Willoughby
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      6(69)Male, sedentary18 (18)33×wk

      12wk
      75%–80%
      Includes 1–2wk of pretraining/orientation at reduced number of sets, reps, and/or intensity – 1 set only.


      3×8–10
      NA60%–65%

      3×15–20
      NANot reportedStrength
      Abbreviations: Ex, exercises; LL, lower limb; NA, not applicable; No., number; reps, repetitions; 6MWT, 6-minute walk test.
      Number of enrolled participants.
      Total duration – some studies included a 1- to 4-wk conditioning period, which gradually increased %RM to the target level.
      Outcomes of interest to this review.
      § Includes 1–2wk of pretraining/orientation at reduced number of sets, reps, and/or intensity – 1 set only.
      Participants 60 years or older.

       Methodologic quality assessment

      Most studies were of poor to moderate methodologic quality and ranged from 3 to 7 (out of 10) on the PEDro scale. No study involved blinded participants or therapists because of the nature of the interventions. Two studies used blinded assessors,
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      and 1 study employed concealed allocation.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      One study reported that groups were not of similar age at baseline.
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      The majority of studies obtained at least 85% of data for a primary outcome,
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      and 6 studies used intention-to-treat analysis.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      All studies reported between-group statistical comparisons and point measures and measures of variability for at least 1 primary outcome.

       Participants

      All participants were untrained in PRST. Group characteristics are summarized in table 1.

       Programs

      Where reported, programs were carried out in community-based training facilities
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      and local fitness centers.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      The length of training sessions was reported in only 7 trials ranging from approximately 45
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      to 90 minutes.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      Some programs included a warm-up
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      prior to PRST and a cool-down
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      after training. Where specified, these warm-up and cool-down programs consisted of low-intensity repetitions of the intended PRST exercise, low-intensity cardiovascular exercise, stretching, and/or calisthenics.
      Programs ranged from 8 to 52 weeks (mean ± SD, 20.5±13.3), with participants attending 2 to 3 times per week.

       Outcome measures

       Lower-limb strength

      Table 2 summarizes the SMDs of HIPRST versus other intensities on maximal lower-limb strength. Positive SMDs favor HIPRST and negative SMDs favor comparison intensity. In the trials that included leg or knee extension, the movements were not described in adequate detail to determine the difference, if any, between these outcomes.
      Table 2Effects of HIPRST versus other intensities of PRST on strength outcomes
      StudyHigh Intensity Resistance % 1RMComparison Intensity 1 % 1RMComparison Training Volume as a % of High Intensity group (%)
      Training volume each session as a percentage of high-intensity training volume. See Methods for further details.
      Outcome
      1RM where not specified.
      SMD95% Confidence Interval or P valueComparison Intensity 2 % 1RMComparison Training Volume as a % of High Intensity Group (%)
      Training volume each session as a percentage of high-intensity training volume. See Methods for further details.
      SMD95% Confidence Interval
      Beneka
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      7050140Knee extensionND90144ND
      Cassilhas
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      Raw data (unpublished) obtained directly from authors.
      805063Leg press0.87(0.22 to 1.53)NA
      Leg curl1.15(0.47 to 1.82)
      Fatouros, Tournis
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      80–8560–6595Leg extension1.14(0.30 to 1.98)45–501012.05(1.11 to 2.98)
      Fatouros
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      As aboveAs aboveAs aboveLeg press0.65(−0.16 to 1.42)45–50As above1.90(0.96 to 2.73)
      Fatouros, Kambas
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      80–8550–55137Leg press1.66(0.91 to 2.41)NA
      Harris
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      7567100Lower body strength
      Combined knee extension, leg press, leg curl.
      0.26(−0.46 to 0.99)84 vs 671000.10(−0.58 to 0.77)
      Hortobagyi
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      8040100Leg press0.40(−0.54 to 1.34)NA
      Max eccentric strength0.11(−0.11 to 0.33)
      Isometric0.03(−0.89 to 0.96)
      Concentric0.49(−0.49 to 1.39)
      Hunter
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      8050, 65, 8082Knee extension0.62(−0.14 to 1.38)NA
      Kalapotharakos
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      8060141Lower body strength
      Combined knee extension and flexion.
      1.00(0.12 to 1.88)
      Kalapotharakos
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      As aboveAs aboveKnee extension1.04(0.16 to 1.92)NA
      Knee flexion0.80(−0.06 to 1.65)
      Pruitt
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      804075Hips
      Hip abduction plus hip adduction.
      0.21(−0.81 to 1.22)NA
      Legs
      Leg press plus knee extension plus knee flexion.
      0.21(−0.94 to 1.36)
      Seynnes
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      804050Knee extension0.62(−0.48 to 1.71)NA
      Singh
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      802025Average strength
      Mean of percent change across 3 upper-limb and 3 lower-limb resistance exercises.
      ND, RSP<.0001NA
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      8010–2025Leg pressND, RNSP>.05NA
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      As aboveAs aboveLeg pressND, RSP<.05NA
      Taaffe
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      804075Leg press
      Outcome measure assessed at 3, 6, 9, and 12 months.
      ND, RNSP>.05NA
      Knee extension
      Outcome measure assessed at 3, 6, 9, and 12 months.
      ND, RS
      Significant at 3 months only.
      P<.05
      Knee flexion
      Outcome measure assessed at 3, 6, 9, and 12 months.
      ND, RNSP>.05
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      75–8555–65105Leg strength (10RM)RNSRNSNA
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      75–8555–65125Leg extension0.23(−0.57 to 1.03)NA
      Vincent et al
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      8050102Leg press0.00(−0.58 to 0.58)NA
      Leg curl0.32(−0.27 to 0.90)
      Leg ext0.29(−0.29 to 0.87)
      Willoughby
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      75–8060–65162Leg press0.62(−0.46 to 1.70)NA
      NOTE. A positive SMD indicates HIPRST having larger strength gains than the comparison group.
      Abbreviations: NA, not applicable; ND, no data; RM, repetition maximum; RNS, reported not significant; RS, reported significant.
      Training volume each session as a percentage of high-intensity training volume. See Methods for further details.
      1RM where not specified.
      Raw data (unpublished) obtained directly from authors.
      § Combined knee extension, leg press, leg curl.
      Combined knee extension and flexion.
      Hip abduction plus hip adduction.
      # Leg press plus knee extension plus knee flexion.
      ∗∗ Mean of percent change across 3 upper-limb and 3 lower-limb resistance exercises.
      †† Outcome measure assessed at 3, 6, 9, and 12 months.
      ‡‡ Significant at 3 months only.

       Lower-limb strength: high versus low

      Seven trials reported on high- versus low-intensity training,
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      with SMDs in favor of HIPRST ranging from .21 to 2.05 (see table 2). One trial revealed large SMDs in favor of HIPRST for knee extension and leg press after 24 weeks in sedentary participants who were men.
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      During one 12-month program, there was no difference between training intensities for knee extension, knee flexion, or leg press strength at 3 monthly time points, except for knee extension strength at 3 months, which was greater in HIPRST participants.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      Another study
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      reported maximal knee extension strength improved significantly with both intensities, with a moderate but not statistically significant effect in favor of HIPRST (SMD=.62; 95% CI, −.48 to 1.71). Other trials found no difference between intensities in 1RM hip and leg strength at 15 and 52 weeks
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      nor for maximal eccentric or isometric quadriceps strength.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      Pooled data from 4 out of 7 trials revealed a large SMD in favor of high-intensity training, but this just failed to reach statistical significance (SMD=.83; 95% CI, −.02 to 1.68). These trials were of moderate to low methodologic quality with PEDro scale scores rating ≤5 (fig 2).
      Figure thumbnail gr2
      Fig 2HIPRST versus LIPRST for maximal lower-limb strength. Abbreviations: IV, inverse variance; Std., standard.

       Lower-limb strength: high versus moderate

      Ten trials (13 articles) compared HIPRST versus MIPRST.
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      The SMDs tended to favor high-intensity training; however, there was marked variability with SMDs ranging from 0 to 1.66 (see table 2) and a pooled SMD of .79 (95% CI, .40–1.17) (fig 3). Studies were grouped by methodologic quality for further analysis and demonstrated consistency of results: lower-quality studies with PEDro scale scores of ≤5 resulted in an SMD of .67 (95% CI, .33–1.02), and those of higher quality (PEDro scale score of ≥6) resulted in an SMD of .80 (95% CI, .39–1.22). Four trials (5 articles) showed statistically significant differences between intensities for leg extension, leg press, leg curl, overall lower-body strength, and knee extension,
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      and 3 studies showed moderate to large SMDs favoring high-intensity training for various lower-limb strength outcomes without statistically significant differences between groups (knee flexion and leg press).
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      Three studies showed small SMDs without statistically significant differences between groups,
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      including no effect for leg press strength.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      Two studies reported insufficient data to analyze differences between intensities.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      Pooled data from 4 trials revealed a WMD of 14.17kg (95% CI, 9.86–18.48) (leg extension, leg press, and knee extension).
      Figure thumbnail gr3
      Fig 3HIPRST versus MIPRST for lower-limb strength. Abbreviations: IV, inverse variance; Std., standard.

       Lower-limb strength: high versus maximal

      One trial reported on high compared with maximal training
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      and tested 1RM knee extensor strength at various speeds, from 60 to 180°/s. They reported a 7.3% to 11.2% increase in strength for men and 2.3% to 15.2% increase for women across all intensities (high, maximal, and moderate) with no between-group comparison.

       Lower-limb strength: high versus variable

      One study reported significant strength gains for knee extension with both variable-intensity and high-intensity training, with no significant difference between intensity types (SMD=.64; 95% CI, −0.14 to 1.38).
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.

       Outcomes other than strength

      Table 3 shows SMDs for other non-strength-related outcome measures.
      Table 3SMD table for high intensity versus other intensity PRST – various outcomes
      StudyHigh Intensity Resistance % 1RMComparison Intensity 1 % 1RMComparison Training Volume as a % of High Intensity Group (%)OutcomeSMD (95% Confidence Interval) or P valueComparison Intensity 2 %1RMComparison Training Volume as a % of High Intensity Group (%)SMD (95% Confidence Interval)
      Beneka
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      7050140Isokinetic peak torque90%144
       Males: knee ext 90° deg/sec0.51 (−0.49 to 1.51)−0.30 (−1.29 to 0.69)
       Females: knee ext 90° deg/sec0.71 (−0.31 to 1.73)−0.71 (−1.71 to 0.31)
       Males: knee ext 60° deg/sec0.63 (−0.38 to 1.64)−0.34 (−1.33 to 0.64)
       Females: knee ext 60° deg/sec−0.10 (−1.08 to 0.88)−1.18 (−2.27 to −0.09)
      Cassilhas
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      805063Quality of lifeND, RNSNA
      Depression – self rated (GDS)ND, RNS
      MoodND, RNS
      CognitionND, RNS
      Fatouros, Tournis
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      80–8560–6595V˙o2 Max0.56 (−0.23 to 1.34)45–501010.50 (−0.28 to 1.29)
      Fatouros
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      80–8560–65As aboveFlexibility – knee flexion0.10 (−0.67 to 0.87)45–50As above0.88 (0.10 to 1.66)
      Flexibility – hip flexion0.04 (−0.73 to 0.82)0.06 (−0.68 to 0.80)
      Flexibility – hip extension0.29 (−0.48 to 1.07)2.93 (1.82 to 4.04)
      Fatouros, Kambas
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      80–8550–55137Peak power0.69 (0.02 to 1.33)NA
      Mean power0.38 (−0.27 to 1.01)
      Timed Up & Go Test−0.07 (−0.70 to 0.57)
      Walking speed−0.05 (−0.68 to 0.59)
      Stepping up−0.18 (−0.82 to 0.46)
      Stepping down−0.21 (−0.85 to 0.42)
      Hortobagyi
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      8040100Explosive strength:NA
       Max rate of tension development0.27 (−0.66 to 1.20)
      Hunter
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      8050, 65, 8082Performing functional tasks:NA
       Perceived exertion0.77 (0.00 to 1.55)
       Submaximal V˙o20.66 (−0.10 to 1.42)
       Relative muscle activation
      As calculated by dividing integrated electromyography of the weight load while walking by maximal elbow flexion.
      1.23 (0.41 to 2.04)
      Kalapotharakos
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      8060141Isokinetic peak torqueNA
       Left knee ext 60° deg/sec−0.06 (−0.93 to 0.82)
       Right knee ext 60° deg/sec0.26 (−0.62 to 1.14)
       Left knee flex 60° deg/sec−0.12 (−1.00 to 0.76)
       Right knee flex 60° deg/sec0.18 (−0.70 to 1.05)
       Left knee ext 180° deg/sec0.30 (−0.58 to 1.17)
       Right knee ext 180° deg/sec0.05 (−0.83 to 0.92)
       Left knee flex 180° deg/sec0.15 (−0.73 to 1.03)
       Right knee flex 180° deg/sec0.14 (−0.74 to 1.02)
      Kalapotharakos
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      8060As aboveFlexibility – sit and reach−0.24 (−1.06 to 0.58)NA
      Walking speed0.12 (−0.70 to 0.94)
      Chair rise0.12 (−0.69 to 0.95)
      Stair climb−0.34 (−1.16 to 0.49)
      Seynnes
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      804050Endurance1.71 (0.42 to 3.01)NA
      Chair rise time−0.06 (−1.12 to 0.99)
      Stair climb power0.29 (−0.78 to 1.35)
      6-minute walk distance0.65 (−0.44 to 1.75)
      Disability (HAQ – DI)0.09 (−0.97 to 1.15)
      Singh
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      802025Quality of life – vitality0.59 (−0.10 to 1.25)NA
      Depression
       Therapist rated (HRSD)−0.15 (−0.82 to 0.51)
       Self-rated (GDS)−0.16 (−0.83 to 0.50)
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      802025Aggregate physical score(sit to stand, stair climb, safe and maximal gait speed)ND, RNSNA
      Sullivan
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      8020As aboveAggregate physical score (as above)NDNA
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      75–8555–65105Physical activity efficacy:
       Walking−0.25 (−0.99 to 0.50)NA
       Stair climb0.40 (−0.35 to 1.15)
      Physical Self-efficacy Scale:
       PPA0.37 (−0.38 to 1.12)
       PSPC−0.54 (−1.29 to 0.22)
      Cognition
       Mental arithmetic0.48 (−0.28 to 1.23)
       Mirror drawing
      Time0.26 (−0.48 to 1.01)
      Dots−0.14 (−0.88 to 0.60)
      Errors−0.97 (−1.77 to −0.16)
      V˙o2 MaxND to RNS
      Tsutsumi
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      75–8555–65125POMS tension0.59 (−0.23 to 1.41)NA
      POMS vigor−0.27 (−1.07 to 0.54)
      State anxiety (STAI)0.27 (−0.53 to 1.08)
      Trait anxiety (STAI)0.86 (0.02 to 1.71)
      V˙o2 MaxND to RNS
      Vincent et al
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women.
      8050102Muscular endurance (leg)0.14 (−0.44 to 0.72)NA
      Stair climb time−0.57 (−1.16 to 0.02)
      Vincent to Braith to Feldman to Kalls et al 20028050As aboveV˙o2 Peak

      Endurance – treadmill time
      −0.06 (−0.63 to 0.52)

      0.25 (−0.34 to 0.82)
      NA
      NOTE. Improvements in depression to stair climbing time to stepping up/down to disability to anxiety to mirror drawing errors (cognition) to and perceived exertion are indicated by a negative SMD. Improvements in all other outcomes are indicated by a positive SMD.
      Abbreviations: Ext to extensors; Flex to flexors; GDS to Geriatric Depression Scale; HAQ DI to Health Assessment Questionnaire Disability Index subscale (French version); HRSD to Hamilton Rating Scale of Depression; Max to maximal; ND to no data; POMS to Profile of Mood States; PPA to Perceived Physical Ability; PSPC to Physical Self-Presentation Confidence; RNS to reported not significant; STAI to State-Trait Anxiety Inventory; V˙o2, oxygen consumption per unit time.
      As calculated by dividing integrated electromyography of the weight load while walking by maximal elbow flexion.

       Power and torque

      High-, maximal-, and moderate-intensity PRST improved isokinetic peak torque (P<.05), with no difference between high- and moderate-intensity training.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      The SMDs favored maximal intensity over high intensity and ranged from −.12 to −1.25. Another study reported statistically significant improvements in isokinetic peak torque after HIPRST and MIPRST, with high-intensity training significantly better than moderate-intensity training on only 1 of the 8 outcomes.
      • Kalapotharakos V.
      • Michalopoulou M.
      • Godolias G.
      • Tokmakidis S.P.
      • Malliou P.
      • Gourgoulis V.
      The effects of high- and moderate-resistance training on muscle function in the elderly.
      A third study reported no statistically significant differences between HIPRST and LIPRST for explosive strength measures, including maximal rate of tension development.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      When investigating peak power, 1 study reported that HIPRST resulted in significantly greater gains than MIPRST (SMD=.69; 95% CI, .02–1.33).
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.

       Endurance

      In residents of aged care facilities, both high- and moderate-intensity training increased knee extension endurance by 284% and 117%, respectively, with significantly greater improvements for HIPRST over MIPRST (SMD=1.71; 95% CI, .42–3.01).
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      In a healthy older population, leg press endurance increased with both high- and moderate-intensity training; however, there was no significant difference between intensities (SMD=.14; 95% CI, −.44 to −.72).
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      In this same population, treadmill time to exhaustion increased with both high- and moderate-intensity training, with no significant difference between intensities (SMD=.25; 95% CI, −.34 to −.82).
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women.

       Cardiovascular fitness

      There was no clear benefit of high-intensity training on peak oxygen consumption
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      or submaximal oxygen consumption
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      over other intensities of training. Two studies found improvement with both HIPRST and MIPRST with no significant difference between groups
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women.
      ; a third study reported no effect with either intensity of PRST.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      Pooled data from 2 studies revealed a WMD of .93mL·kg−1·min−1 (95% CI, −.69 to 2.55). When compared with variable intensity training, there was a moderate but nonsignificant effect on submaximal oxygen consumption in favor of variable intensity (SMD=.66; 95% CI, −.10 to 1.42).
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.

       Flexibility

      Two studies examined flexibility. One trial
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      reported both HIPRST and MIPRST significantly improved sit and reach with no difference between intensities. Mean improvements across training groups were approximately 3.5 to 5cm: a 13% and 15.5% increase from baseline for HIPRST and MIPRST, respectively.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      A second trial
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      also reported significant improvements with both HIPRST and MIPRST in flexibility. Knee flexion and hip extension range improved with no difference between intensities. There were large and statistically significant SMDs with HIPRST over LIPRST for increasing knee flexion and hip extension range. Across all intensities tested, the increase in range was 5° to 14° of knee flexion and 0.3° to 4.7° for hip extension, with the largest gain of 4.7° of hip extension after HIPRST. There was no improvement in the hip flexion range for any intensity examined.
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.

       Functional performance

      Both variable PRST and HIPRST reduced perceived exertion while carrying an object with a larger reduction observed in those who received variable resistance training (SMD=−.77; 95% CI, −1.55 to 0.00). Relative muscle activation was calculated by dividing the integrated electromyography measured during the weighted walking task by maximal elbow flexion. This was reduced only in the variable intensity group, with a large SMD. Two studies reported reductions in stair climb time with HIPRST versus MIPRST (SMD=−.34; 95% CI, −1.16 to .49
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      and SMD=−.57; 95% CI, −1.16 to .02,
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      respectively). A small but nonsignificant improvement in stair climb power was reported for HIPRST over LIPRST.
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      One trial (2 articles) examined an aggregate physical performance score, which included sit to stand time, habitual and maximal safe walking speeds, and stair climb time,
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      and reported similar improvements in performance with high- and low-intensity training with no difference between intensities (P>.05). The authors reported that those with the lowest scores at baseline had the greatest improvements,
      • Sullivan D.H.
      • Roberson P.K.
      • Smith E.S.
      • et al.
      Effects of muscle strength training and megestrol acetate on strength, muscle mass, and function in frail older people.
      independent of training intensity.
      There were significant improvements with both HIPRST and LIPRST for chair-rise time with no difference between intensities (SMD=−.06; 95% CI, −1.12 to 1.00).
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      HIPRST improved six-minute walk test distance more than moderate-intensity training, with a moderate but not significant effect (SMD=.65; 95% CI, −.44 to 1.75).
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.

       Disability

      Disability, as measured by the Health Assessment Questionnaire Disability Index, was reduced by both high and low intensities with no difference between intensities
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      (SMD=.09; 95% CI, −.97 to 1.15).

       Falls

      Falls rate was reported in 1 study in an older population with depression.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      While there were less falls per person in the HIPRST group when compared with the LIPRST group (mean ± SD, .15±.37 and .28±.75, respectively), this was not statistically significant.

       Hospitalization

      Number of days spent in hospital was also reported in an older population with depression over an 8-week period. These were 0.5±0.2 days per person in the HIPRST group compared with none in the LIPRST, reported to be not statistically significant.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.

       Quality of life

      QOL was reported in 2 studies using the Medical Outcomes Study 36-Item Short-Form Health Survey.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      There was no improvement in QOL with moderate- or high-intensity training in any of the domains in Medical Outcomes Study 36-Item Short-Form Health Survey reported (P>.05).
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      However, another study showed moderate improvements in the vitality domain for high- over low-intensity training in an older population with depression (SMD=.59; 95% CI, −.10 to 1.25).
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      In this study, both HIPRST and LIPRST were reported to improve QOL across 6 of the 8 health-related QOL domains: physical function, role physical, vitality, social function, role emotional, and mental health (P range, <.001–.04).

       Psychological status

      One study reported no improvement in self-rated depression (Geriatric Depression Scale [GDS]) with HIPRST or MIPRST in a sedentary, older population of men (P>.05).
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      In an older population with a diagnosis of depression, HIPRST participants experienced more than twice the relative response of LIPRST participants in both the GDS (58%±7% vs 23%±7%) and the Hamilton Rating Scale for Depression (52%±7% vs 25%±8%).
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      Sixty-one percent of HIPRST participants had a clinically important response (a 50% improvement in therapist-rated scores) compared with 29% of LIPRST participants (P=.05). The authors described a significant inverse relation between strength and self-reported depression levels with high-intensity exercise only.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      Mood was reported in 2 studies investigating MIPRST and HIPRST. One study reported that both intensities improved overall mood scores (Profile of Mood States [POMS]), with no statistically significant difference between intensities (P>.05).
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      The second study reported that MIPRST tended to improve the POMS-tension domain more than HIPRST (SMD=.59; 95% CI, −.23 to 1.41).
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      In the same study, trait anxiety, as measured by the State and Trait Anxiety Inventory, was significantly lessened with MIPRST compared with HIPRST (SMD=.86; 95% CI, .02–1.71).
      Two studies investigated the effects of HIPRST and MIPRST on cognition. One reported improvements in cognitive functioning for both high and moderate intensities in some areas of cognitive testing (Digit Span Forward, Corsi Block-Tapping Task Backward, similarities, Rey-Osterreith Complex Figure Immediate Recall), with no difference between intensities (P>.05).
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      This population had at least 8 years of schooling and a Mini-Mental State Examination score of ≥24 (out of 30). The other study found no treatment effects for neurocognitive function in healthy but sedentary older adults with at least a high school education.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.

       Program duration

      There was no strong link between duration of the HIPRST program and 1RM strength outcomes (fig 4). Some shorter programs (range, 8–12wk) were sufficient to produce significantly greater strength gains for HIPRST compared with lesser intensities.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      Figure thumbnail gr4
      Fig 4Effect of program duration on lower-limb 1RM strength outcomes. An SMD >0 favors HIPRST.

       Training volumes

      Seven out of 8 trials where the groups undertook similar training volumes (comparison of 75% to 125% of the HIPRST volume) displayed similar lower-limb strength gains, regardless of training intensity
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      (see table 2). There was no clear link between the magnitude of strength increase and training volume across studies; larger training volumes did not necessarily result in larger strength gains. Conversely, smaller training volumes did not result in lesser strength gains.

       Adherence

      Where reported, drop outs ranged from 0%
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      to 44%
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      of participants, and adherence to training ranged from 66%
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      to 100%
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      of sessions. Reasons for lack of adherence and drop outs ranged from lack of interest,
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      personal reasons,
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      medical reasons unrelated to the study,
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      conflicts arising from project/job,
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      commuting issues,
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      and pain or injury.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      On analysis of all reported data, adherence and drop outs did not differ according to training intensity.

       Adverse events

      Eight studies did not specifically state the absence or presence of adverse events.
      • Cassilhas R.C.
      • Viana V.A.
      • Grassmann V.
      • et al.
      The impact of resistance exercise on the cognitive function of the elderly.
      • Taaffe D.R.
      • Pruitt L.
      • Pyka G.
      • Guido D.
      • Marcus R.
      Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Takenaka K.
      • Oka K.
      • Ohno T.
      Comparison of high and moderate intensity of strength training on mood and anxiety in older adults.
      • Beneka A.
      • Malliou P.
      • Fatouros I.
      • et al.
      Resistance training effects on muscular strength of elderly are related to intensity and gender.
      • Kalapotharakos V.I.
      • Michalopoulos M.
      • Tokmakidis S.P.
      • et al.
      Effects of a heavy and a moderate resistance training on functional performance in older adults.
      • Tsutsumi T.
      • Don B.M.
      • Zaichkowsky L.D.
      • Delizonna L.L.
      Physical fitness and psychological benefits of strength training in community dwelling older adults.
      • Willoughby D.S.
      • Pelsue S.C.
      Muscle strength and qualitative myosin heavy chain isoform mRNA expression in the elderly after moderate- and high-intensity weight training.
      • Hunter G.R.
      • Wetzstein C.J.
      • McLafferty Jr., C.L.
      • Zuckerman P.A.
      • Landers K.A.
      • Bamman M.M.
      High-resistance versus variable-resistance training in older adults.
      Nine studies reported on the presence of adverse events
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      ; however, these were generally not reported in detail. Two of these studies reported no training-induced adverse events,
      • Seynnes O.
      • Fiatarone Singh M.A.
      • Hue O.
      • et al.
      Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
      • Harris C.
      • DeBeliso M.A.
      • Spitzer-Gibson T.A.
      • Adams K.J.
      Effect of resistance-training intensity on strength-gain response in the older adult.
      and 2 reported injuries without detail.
      • Fatouros I.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent.
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      The remainder of studies
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      • Vincent K.R.
      • Braith R.W.
      • Feldman R.A.
      • et al.
      Resistance exercise and physical performance in adults aged 60 to 83.
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      reported adverse events that ranged from musculoskeletal discomfort to the exacerbation of underlying medical conditions
      • Pruitt L.
      • Taaffe D.R.
      • Marcus R.
      Effects of a one- year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
      to a more serious event in 1 trial. This was an exacerbation of chronic obstructive pulmonary disease and myocardial infarction 3 days post-HIPRST.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      Although independent monitors suggested that the exercise program could have contributed, the authors stated that HIPRST remains safe for older adults to undertake.
      Where injuries were reported, rates of injury appeared comparable among high-, moderate-, and low-intensity training. One trial reported no difference in adverse events between those participating in various intensities of PRST and those not.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.

       Sensitivity analysis for definitions of intensity

      Sensitivity analyses were limited by the small number of trials comparing extreme values of intensity (ie, high vs low). However, where data were available, the pattern of findings was similar to when all 3 intensities were considered. Sensitivity analysis for the outcomes of maximal strength showed moderate to large effects for HIPRST over LIPRST in 3 out of 7 trials, with statistically significant differences in 3 other trials where raw data were unable to be obtained. There were only 2 trials which had similar training volumes across high and low intensities. These trials showed disparate effects, with 1 trial showing no significant benefit of HIPRST over LIPRST (SMD=0.4)
      • Hortobagyi T.
      • Tunnel D.
      • Moody J.
      • Beam S.
      • DeVita P.
      Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults.
      and the other favoring HIPRST with a large effect (SMD=2.05).
      • Fatouros I.G.
      • Tournis S.
      • Leontsini D.
      • et al.
      Leptin and adiponectin responses in overweight inactive elderly following resistance training and detraining are intensity related.
      While only examined in single trials, depression,
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      QOL,
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      and flexibility
      • Fatouros I.G.
      • Kambas A.
      • Katrabasas I.
      • et al.
      Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.
      demonstrated significantly larger effects when HIPRST was compared with LIPRST than when HIPRST was compared with MIPRST, although raw data were not available for analyses on depression and QOL. Adverse events and drop outs were similar across high- and low-intensity training. Although not able to be performed on all outcomes in this meta-analysis, sensitivity analyses support the between-group differences, favoring high-intensity training that was found in the primary analyses.

      Discussion

      This meta-analysis has shown that HIPRST demonstrates advantages over lower intensities of PRST. However, trials with similar training volumes had similar gains in lower-limb strength, regardless of training intensity. Other outcomes, such as functional performance, improved similarly across all intensities of PRST. Flexibility increased more with HIPRST and MIPRST than LIPRST. The effects of HIPRST compared with other intensities of PRST on psychological status remains unclear.
      Although there were greater improvements in strength with high-intensity training compared with moderate- and low-intensity training (see figs 2 and 3), this was not consistent across all trials. Training volume also appears to have an important effect on strength, with similar gains seen in training groups who performed a similar volume of PRST, regardless of absolute intensity. These results suggest that clinicians should consider whether there is a need for older participants to undertake HIPRST if the primary goal is to improve strength.
      Reduced flexibility may contribute to limited function
      • Jette A.M.
      • Branch L.G.
      • Berlin J.
      Musculoskeletal impairments and physical disablement among the aged.
      • Bergström G.
      • Aniansson A.
      • Bjelle A.
      • Grimby G.
      • Lundgren-Lindquist B.
      • Svanborg A.
      Functional consequences of joint impairment at age 79.
      and falls
      • Kerrigan D.C.
      • Lee L.W.
      • Collins J.J.
      • Riley P.O.
      • Lipsitz L.A.
      Reduced hip extension during walking: healthy elderly and fallers versus young adults.
      in older adults. Studies in younger adults have shown strength training does not impair flexibility; in some cases it may improve it
      • Thrash K.
      • Kelly B.
      Flexibility and strength training.
      to levels comparable with static stretching.
      • Morton S.K.
      • Whitehead J.R.
      • Brinkert R.H.
      • Caine D.J.
      Resistance training vs. static stretching: effects on flexibility and strength.
      In this review, both HIPRST and MIPRST have been shown to increase flexibility to similar extents and were more beneficial than LIPRST. It has been suggested that strengthening muscle groups may also improve range of movement across the joints that these muscles span.
      • Fatouros I.G.
      • Taxildaris K.
      • Tokmakidis S.P.
      • et al.
      The effects of strength training, cardiovascular training and their combination on flexibility of inactive older adults.
      Functional improvements have been demonstrated with HIPRST in older adults in other studies, with improvements in ability to stand from a chair,
      • Rosendahl E.
      • Lindelof N.
      • Littbrand H.
      • et al.
      High-intensity functional exercise program and protein-enriched energy supplement for older persons dependent in activities of daily living: a randomised controlled trial.
      • Fiatarone M.
      • Marks E.
      • Ryan N.
      • Meredith C.
      • Lipsitz L.
      • Evans W.
      High-intensity strength training in nonagenarians: effects on skeletal muscle.
      reduced need for walking aids,
      • Fiatarone M.
      • Marks E.
      • Ryan N.
      • Meredith C.
      • Lipsitz L.
      • Evans W.
      High-intensity strength training in nonagenarians: effects on skeletal muscle.
      and self-paced gait speed.
      • Rosendahl E.
      • Lindelof N.
      • Littbrand H.
      • et al.
      High-intensity functional exercise program and protein-enriched energy supplement for older persons dependent in activities of daily living: a randomised controlled trial.
      Results from this review are consistent with this literature, however, walking speed, functional performance, and disability were found to improve similarly with MIPRST and LIPRST, also supported by other meta-analyses.
      • Steib S.
      • Schoene D.
      • Pfeifer K.
      Dose-response relationship of resistance training in older adults: a meta-analysis.
      Therefore, high intensity may not be required to improve functional performance, and lesser intensities may suffice.
      While there was no significant benefit in overall QOL from HIPRST compared with other intensities, a trend for improvement was shown for components of QOL measures.
      • Singh N.A.
      • Stavrinos T.M.
      • Scarbek Y.
      • et al.
      A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults.
      Mixed results for other psychological outcomes were reported. Other research has reported HIPRST programs having reduced depressive symptoms in those with both minor and major depression, with the majority of exercisers no longer meeting the diagnostic criteria for depression after 10 weeks of exercise. Increased training intensity was also reported to predict the reduction in depressive symptoms.
      • Singh N.A.
      • Clements K.M.
      • Fiatarone M.A.
      Randomized controlled trial of progressive resistance training in depressed elders.
      Previous systematic reviews on exercise for depression suggest exercise may reduce depression in this population in the short-term; however, more robust, larger, and longer-term randomized controlled trials are required to define the parameters around the type of exercise, intensity, duration of programs, and target populations for optimal outcomes.
      • Mead G.
      • Morley W.
      • Campbell P.
      • Greig C.
      • McMurdo M.
      • Lawlor D.
      Exercise for depression.
      • Lawlor D.A.
      • Hopker S.W.
      The effectiveness of exercise as an intervention in the management of depression: systematic review and meta-regression analysis of randomised controlled trials.
      There was no obvious relation between program duration and outcome, suggesting that longer programs are not required to achieve additional benefits. Shorter HIPRST programs of 12 weeks demonstrated significantly greater gains in outcomes, such as strength and endurance, than lower intensities of training. Because positive results may be seen within 2 to 3 months of HIPRST, this finding may encourage potential participants to undertake such a program, particularly where time commitments may be a barrier. This is also positive for clinicians in community-based settings, where longer programs may be cost-prohibitive and unfeasible because of long waiting lists.
      Less than one third of the included studies reported on adverse events related to training; however, events were not reported in adequate detail for further analysis. Nearly half of the trials did not report the presence or absence of adverse events, and therefore it is plausible that underreporting occurred. The majority of events reported were minor musculoskeletal injuries, and there were no deaths because of high-intensity training. There was no difference in rates of adverse events between intensities of training. The single serious adverse event occurred 2 to 3 days after training, and it was unclear if this event occurred in the placebo or drug group.
      • Sullivan D.H.
      • Roberson P.K.
      • Johnson L.E.
      • et al.
      Effects of muscle strength training and testosterone in frail elderly males.
      Because of this period of delay, it would seem unlikely that strength training caused these events. HIPRST has been reported to be safe in older adults up to the age of 96 years.
      • Fiatarone M.
      • Marks E.
      • Ryan N.
      • Meredith C.
      • Lipsitz L.
      • Evans W.
      High-intensity strength training in nonagenarians: effects on skeletal muscle.
      • Fiatarone M.A.
      • O'Neill E.F.
      • Ryan N.D.
      • et al.
      Exercise training and nutritional supplementation for physical frailty in very elderly people.
      Prior to implementation, medical screening of potential participants and supervised programs should be considered.

       Study limitations

      This review had some limitations. While some of the SMDs calculated were moderate to large, many were not statistically significant. This may have been because of the lack of power in studies because of small sample sizes. Caution must also be used when interpreting studies with low methodologic quality, because many studies did not use intention-to-treat analysis, concealed allocation, or blinded assessors, which reduced internal validity and may have overestimated the effect of the interventions. Prior training status has been reported to be an important factor in determining the most effective training intensity for optimal strength outcomes across the age spectrum, where moderate intensity may result in better outcomes in the untrained and high intensity may be more effective in those who are trained.
      • Rhea M.R.
      • Alvar B.A.
      • Burkett L.N.
      • Ball S.D.
      A meta-analysis to determine the dose response for strength development.
      This effect was not considered in the review. Meta-analyses were limited for outcomes other than strength, and raw data were unable to be obtained in many instances. Because most participants were sedentary and previously untrained in PRST, the findings from this review may have limited application to physically active or trained older adults.
      The literature in this area also had some limitations. The trials included in this systematic review contained programs of PRST primarily run in the community with resistance machines. Only 1 trial used elastic bands, which may be a low-cost equipment option in hospitals and community settings. Although resistance bands have been shown to achieve comparable strength gains compared with weight machines in a few studies,
      • Vanbiervliet W.
      • Pelissier J.
      • Ledermann B.
      • Kotzki N.
      • Benaim C.
      • Herisson C.
      • Colado J.
      • Triplettt T.
      Effects of a short-term resistance program using elastic bands versus weight machines for sedentary middle aged women.
      • Andersen L.
      • Andersen C.
      • Mortensen O.
      • Poulsen O.
      • Bjornlund I.
      • Zebis M.
      Muscle activation and perceived loading during rehabilitation exercises: comparison of dumbbells and elastic resistance.
      to our knowledge, there are no similar comparison studies in older adults undertaking HIPRST. Outcomes other than strength were reported in few studies. There were no trials on the effect of HIPRST in hospitalized older adults, where HIPRST may play an important part in falls rate, length of stay, and health service use. There is a need for further research into outcomes other than strength, in particular with a focus on older adults with various health conditions in different settings through the care continuum.

      Conclusions

      HIPRST may improve strength more than lower intensities of strength training, although training volume also has an important effect on the strength gains achieved. Training intensity did not appear to impact greatly on outcomes other than strength. Long programs of HIPRST are not required to see initial benefits or to achieve additional improvements. Adverse events related to strength training in older adults are minor; however, screening prior to implementing new programs is recommended to minimize participant discomfort.
      Future research needs to establish whether HIPRST results in clinically meaningful improvements in important outcomes, such as falls, hospitalization, and use of health care services. Larger trials are required, with particular emphasis on subgroups of older adults with chronic diseases, those who are hospitalized, and those in residential aged care.

      Supplier

      Acknowledgments

      We thank R.C. Cassilhas, PhD, and M.T. Mello, PhD, for providing additional raw data for this review, as well as G. Gaesser, PhD, and R. Wiswell, PhD, for permission to reprint materials. We also thank Karen Perkins, BPhysio, MBA, and the Physiotherapy Department at Caulfield Hospital for their ongoing support.

      Appendix 1. Terms Used in the Search Strategy

      Tabled 1
      PopulationInterventionOutcome
      Exp aged/
      • Resistance training/
      • Strength training.ti.ab.
      • Progressive resistance.ti.ab.
      • High intensity
      • Resistance exercise.ti.ab.
      • Exercise therapy/
      • Exercise
      • Weight lifting
      • Repetition maximum.mp
      • 1RM.mp

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