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Rehabilitation Research Laboratory 2rLab, Rehabilitation and Exercise Science Group, Department of Business Economics, Health, and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart/Manno, SwitzerlandInternational University of Applied Sciences THIM, Landquart, SwitzerlandFaculty of Physical Education and Physiotherapy, Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, BelgiumDepartment of Health, Bern University of Applied Sciences, Berne, Switzerland
Rehabilitation Research Laboratory 2rLab, Rehabilitation and Exercise Science Group, Department of Business Economics, Health, and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart/Manno, Switzerland
Rehabilitation Research Laboratory 2rLab, Rehabilitation and Exercise Science Group, Department of Business Economics, Health, and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart/Manno, SwitzerlandInternational University of Applied Sciences THIM, Landquart, SwitzerlandSchool of Sport, Health, and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
Rehabilitation Research Laboratory 2rLab, Rehabilitation and Exercise Science Group, Department of Business Economics, Health, and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart/Manno, Switzerland
Local heat applications can have a positive effect on pain, physical function, disability, range of motion, quality of life, muscular strength, and tissue stiffness.
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The positive effects of local heat applications can be observed predominantly in acute conditions.
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Long-term effects and effects in chronic conditions are questionable and need further investigations.
Abstract
Objectives
The aim of this systematic review and meta-analysis was to evaluate the effectiveness of local heat applications (LHAs) in individuals with acute or chronic musculoskeletal disorders.
Data Sources
An electronic search was conducted on MEDLINE, Cochrane Controlled Register of Trials, Current Nursing and Allied Health Literature, and the Physiotherapy Evidence databases up to December 2019.
Study Selection
Studies incorporating adults with any kind of musculoskeletal issues treated by LHA compared with any treatment other than heat were included.
Data Extraction
Two authors independently performed the methodological quality assessment using the Cochrane Risk of Bias tool.
Data Synthesis
LHA showed beneficial immediate effects to reduce pain vs no treatment (P<.001), standard therapy (P=.020), pharmacologic therapy (P<.001), and placebo/sham (P=.044). Physical function was restored after LHA compared with no treatment (P=.025) and standard therapy (P=.006), whereas disability improved directly after LHA compared with pharmacologic therapy (P=.003) and placebo/sham (P<.028). Quality of life was improved directly after LHA treatment compared with exercise therapy (P<.021). Range of motion increased and stiffness decreased after LHA treatment compared with pharmacologic therapy (P=.009, P<.001) and placebo/sham (P<.001, P=.023). The immediate superior effects of LHA on muscular strength could be observed compared with no treatment (P<.001), cold (P<.001), and placebo/sham (P=.023).
Conclusions
Individuals with acute musculoskeletal disorders might benefit from using LHA as an adjunct therapy. However, the studies included in this meta-analysis demonstrated a high heterogeneity and mostly an unclear risk of bias.
Musculoskeletal disorders impair physical function and often lead to pain. Those symptoms also appear in healthy individuals or rehabilitation patients after exhaustive or uncommon muscle activity. These activities may cause exercise-induced muscle damage
Superficial LHAs are inexpensive, bearing no negative effects when used correctly. The physiological effects of LHA include increased skin temperature,
Paraspinal musculature and skin temperature changes: comparing the ThermaCare HeatWrap, the Johnson & Johnson back plaster, and the ABC Wärme-Pflaster.
Paraspinal musculature and skin temperature changes: comparing the ThermaCare HeatWrap, the Johnson & Johnson back plaster, and the ABC Wärme-Pflaster.
Therefore, LHAs have the potential to improve treatment outcomes such as pain, strength, stiffness, ROM, and quality of life (QOL) in acute and chronic musculoskeletal conditions. However, to date, the use of LHA has not been evaluated using a meta-analysis approach.
Although some studies describe the beneficial effects of LHAs in the treatment of musculoskeletal disorders, there is limited overall evidence to support the use of topical heat in general.
Therefore, the aim of this review and meta-analysis was to assess the effects of LHA on pain, muscular strength, ROM, stiffness, physical function, QOL, and disability in individuals with any type of musculoskeletal disorders compared with any treatment other than heat (1) immediately after the intervention (pre to post) and (2) in the follow-up period up to 1 month.
Methods
This work is registered (CRD42019133197) in the International Prospective Register of Systematic Reviews (PROSPERO).
Search strategy and inclusion criteria
A systematic literature search was performed in Medical Literature Analysis and Retrieval System Online (PubMed/MEDLINE), Cochrane Controlled Register of Trials, Current Nursing and Allied Health Literature, and Physiotherapy Evidence databases from the earliest available record to December 2019. Search terms were combined using the Boolean operators “AND”/ “OR” (table 1), and search algorithms were adapted for the different databases. The filters “language” (Dutch, English, French, German, Italian, Spanish) and “human” were used. Reference lists of the selected articles were screened for related articles.
Inclusion criteria served as Population, Intervention, Comparator, Outcomes, and Study Designs scheme and were set a priori according the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement
The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration.
: (1) Participant: individuals aged ≥18 years with any kind of musculoskeletal disorders and/or musculoskeletal pain (including DOMS); (2) Intervention: any type of superficial LHA (eg, wraps); (3) Comparator: no treatment, cold therapy, exercise therapy, standard treatment (eg, information, relaxation), pharmacologic therapy, placebo/sham therapy; (4) Outcomes: pain, physical function, disability, muscular strength, QOL, ROM, or stiffness; and (5) Study design: randomized controlled trials and clinical controlled trials. Studies on patients with tumors, topical (eg, ointments), whole or multiple body (eg, balneotherapy), or radiative heat applications (eg, infrared), and deep-heat methods
(eg, diathermy) were excluded. For the purpose of this review, physical function was defined as “patient-reported measures of functional limitations of daily living and activities,”
An empirical exploration of the relations between the health components of the International Classification of Functioning, Disability and Health (ICF).
The searching and selection processes started by screening the retrieved articles based on the title and abstract by 2 independent researchers (R.S., E.H.). The full texts of the selected articles were read independently (R.S., C.D.). In case of disagreement, a third researcher was asked (R.C.) for consensus.
Data extraction and measures of treatment effect
A customized data sheet was used for data extraction. Two independent researchers (R.S., R.C.) performed the data extraction, with a third reviewer (J.T.) consulted in case of disagreement. Musculoskeletal disorders of the studies’ populations were classified into acute or chronic as described by the studies. In dubiety, the definition by Treede et al 2015 was followed.
Immediate pre- to postintervention and follow-up results measured after 48 hours, 72 hours, and up to 1 month between LHA and control treatment of the outcome variables were extracted. Mean and SD were extracted or calculated if adequate variability measures were presented. Reported interquartile ranges were transformed into SD.
Each domain was graded as “low” (+) if RoB was low, as “high” (−) if RoB was high, and as “unclear” (?) if data were insufficient to state a clear rating. All ratings were independently performed by 2 reviewers (R.S., D.A.). In case of disagreement, a third reviewer (R.C.) was asked for consensus.
Data analysis
The meta-analysis calculations and preparation of the forest plots were conducted using the Comprehensive Meta-Analysis software.a A random-effects model was used to account for the heterogeneous nature of the included studies. Weighting factors were calculated based on the DerSimonian and Laird inversed-variance method.
Standardized mean difference (SMD) was calculated to describe the individual studies’ effect size (ES). The corresponding 95% confidence intervals (CIs) around individual studies’ ES and around the overall weighted mean ES estimate were calculated. Results are graphically presented as forest plots. ES interpretation was performed following Cohen's benchmarking: SMD<0.20 (negligible effect), SMD between 0.20-0.49 (small effect), SMD between 0.50-0.79 (moderate effect), and SMD≥0.80 (large effect).
Cochran Q test was applied to test the null hypothesis of no heterogeneity (ie, that all studies have a common ES). The Q value, the corresponding degrees of freedom, and the corresponding exact P value were reported. Higgins’ I2 value was computed to interpret the amount of the total observed variance that can be explained by the true between studies variance (rather than random sampling error). For the interpretation of the observed between-studies heterogeneity, Higgins’ benchmarking values were followed: I2 around 25% (low), I2 around 50% (moderate), and I2 around 75% or more (high).
If adequate, subgroup analysis was performed to specify the effects of LHA on patients with acute and chronic musculoskeletal disorders. Further, a subgroup analysis was also performed to examine the ES extracted from studies on individuals without musculoskeletal disorders (with DOMS) with ES from studies investigating individuals with a musculoskeletal disorder (eg, knee osteoarthritis). Whenever 2 or more studies per outcome parameter was available, a subgroup follow up analysis on acute and chronic conditions was performed for 48 hours,72 hours, and 1 month after the last treatment in an attempt to explain the observed heterogeneity. Subgroup analyses were conducted assuming a common variance, because of the low numbers of studies within the subgroups. Thus, T2 was pooled and used as the common (more accurate) between-studies variance across all subgroups.
Borenstein M, Hedges L, Rothstein H. Meta-analysis: fixed effect vs. random effects. 2007. Available at: https://www.Meta-Analysis.com. Accessed September 6, 2021.
Sensitivity analysis was conducted to test the robustness of the overall weighted mean ES against extreme individual studies’ ES by excluding the corresponding study or studies from the meta-analysis. In this event, results were mentioned before and after the sensitivity analysis.
Results
Included studies and methodological quality
In this systematic review and meta-analysis, a total of n=25 studies fulfilled the a priori set inclusion criteria. From the total of N=1352 participants, n=849 were in the LHA group and n=803 were in the control group. Figure 1 displays the search and selection process.
Fig 1Flowchart of study selection process. CENTRAL, Cochrane Controlled Register of Trials; CINAHL, Cumulative Index to Nursing and Allied Health; PEDro, Physiotherapy Evidence Database.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
Borenstein M, Hedges L, Rothstein H. Meta-analysis: fixed effect vs. random effects. 2007. Available at: https://www.Meta-Analysis.com. Accessed September 6, 2021.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
RCT Heat vs exercise therapy Heat vs standard treatment
Low back pain (acute) N=67 (M/F: NM) (age NM)
Heat wrap (40°C) 8 h/d for 5 d n=22
Full ROM flexion and extension exercises 3 × 1-2 sets of 15-20 reps under supervision plus daily at home 1 × /h when awake for 5 d n=24 Acute low back pain guide booklet n=21
Disability: RMQ (FU 48h) Pain: VAS (FU 48h) PFU: rating of perceived capacity (FU 48h)
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
The RoB analysis (fig 2, fig 3) indicated a low (14/25 studies) and unclear selection bias (11/25 studies) for random sequence generation. Insufficient data reporting led to an unclear RoB for allocation concealment (19/25 studies). The difficulties of blinding in LHA studies are reflected in the high risk of performance (17/25 studies) and detection bias (14/25 studies). Similarly, insufficient data reporting induced an unclear risk of detection bias (11/25 studies). Most of the included studies had a low risk of attrition bias (21/25 studies). Reporting and other bias were rated in all studies as unclear on account of data reporting or lack of published study protocols.
Fig 2Risk of bias analysis of each included study.
Figure 3 displays the classified RoB of all analyzed studies separately.
LHA vs no treatment
Pain and DOMS
The effect of LHA vs no treatment on pain revealed an overall, large effect favoring LHA (SMD=−0.802 [95% CI, −1.0 to −0.5]) with a high and significant heterogeneity (Q8=36.4; P<.001; I2=78.0%) (fig 4). The sensitivity analysis, excluding 1 outlier
(demonstrate an extremely high ES in favor of LHA) (see fig 4), showed that LHA remained significant compared with no treatment to decrease pain (SMD=−0.664 [95% CI, −0.9 to −0.3]).
Fig 4Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs no treatment. The diamonds represent the overall weighted mean ES.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
that examined low back pain observed that LHA was more beneficial compared with no treatment (P=.017). Contrary to these observations, LHA was not superior compared with no treatment in reducing pain in chronic conditions
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
from the same research group investigated the effects on DOMS immediately after LHA and favored LHA to restore muscular strength compared with no treatment (SMD=−1.737 [95% CI, −2.4 to −1.02]), demonstrating a low heterogeneity (Q1=0.001; P=.969; I2=0.0%) (see fig 4).
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
investigating chronic musculoskeletal conditions found no differences between LHA and control treatment on QOL (SMD=−0.492 [95% CI, −1.0 to 0.02]; Q1=0.02; P=.882; I2=0.0%) (see fig 4).
Range of motion
LHA did not alter ROM immediately after treatment (SMD=−0.576 [95% CI, −2.5 to 1.3]; Q1=11.70; P=.001; I2=91.4%) (see fig 4) in acute
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect between LHA and cold therapy resulted in a nonsignificant difference (SMD=−0.184 [95% CI, −0.6 to 0.3]) with a moderate heterogeneity (Q5=14.2; P=.014; I2=64.9%) (fig 5).
Fig 5Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs cold therapy. The diamonds represent the overall weighted mean ES.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
Controversially after 72 hours, the effects of LHA vs cold therapy demonstrated that LHA was superior to cold in reducing pain in acute conditions (SMD=−1.743 [95% CI, −3.0 to −0.3]).
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
One study conducted a 1-month follow up measurement to evaluate the potential effects of LHA and cold on pain and found no (P=.85) significant difference between the 2 interventions.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The study of Petrofsky et al showed, that LHA has a positive effect on restoring muscular function immediately after LHA treatment (P<.001; Q0=0.000; P>.99; I2=0.0%)
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
result showed that LHA is ineffective to immediately affect tissue stiffness compared with cold therapy (P=.943; Q0=0.000; P>.99; I2=0.0%) (see fig 5).
LHA vs exercise
Effects on pain
Compared with exercise, LHA was not beneficial to reduce pain immediately after the treatment (SMD=−0.415 [95% CI, −1.0 to 0.1]; Q2=4.966; P=.083; I2=59.7%) (fig 6).
Fig 6Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs exercise therapy. The diamonds represent the overall weighted mean ES.
In a comparison of the immediate effects between LHA and exercise therapy on physical function and disability, LHA had no effect on physical function compared with exercise (SMD=−0.478 [95% CI, −1.4 to 0.4]; Q2=7.027; P=.03; I2=71.5%) (see fig 6).
showed that LHA was also not superior to exercise to positively influence disability (SMD=−0.146 [95% CI, −0.8 to 0.5]; Q1=0.062; P=.830; I2=0.0%) (see fig 6).
(SMD=−1.499 [95% CI, −2.7 to −0.2]) with a high and significant heterogeneity (Q1=6.204; P=.013; I2=83.8%) (see fig 6).
LHA vs standard therapy
Effects on pain
LHA was found to be beneficial compared with standard therapy in reducing pain (SMD=−0.784 [95% CI, −1.4 to −0.1]). However, the included studies showed a high and significant heterogeneity (Q5=33.753; P<.001; I2=85.1%) (fig 7).
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
Fig 7Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs standard therapy. The diamond represents the overall weighted mean ES.
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
conditions separately from each other, our analysis revealed that LHA is effective in acute (SMD=−1.265 [95% CI, −2.0 to −0.4]) but not chronic (SMD=−0.227 [95% CI, −0.5 to 0.1]) conditions.
investigated the effects after 48 hours and found a positive effect in favor for LHA (MD=−2.330 [95% CI, −3.1 to −1.4]) compared with standard therapy. After 1 month, LHA was still superior to standard therapy to decrease pain
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
performed follow-up measurements after 48 hours and observed that LHA was not superior to standard therapy to restore disability (SMD=0.090 [95% CI, −0.5 to 0.7]).
After 1 month, LHA was effective to restore disability compared with standard therapy (MD=−0.664 [95% CI, −1.2 to −0.04] in 1 study.
The effects between LHA and standard therapy on QOL showed no significant differences between LHA and standard therapy (MD=−0.527 [95% CI, −1.2 to 0.2]; Q0=0.0; P>.99; I2=0.0%) (see fig 7).
Fig 8Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs pharmacologic therapy. The diamonds represent the overall weighted mean ES.
At 48-hour follow-up the results from Nadler et al showed that compared with pharmacologic therapy, LHA was effective to reduce pain (SMD=−0.462 [95% CI, −0.7 to −0.1]).
compared LHA and pharmacologic therapy on physical function and found no effect between the interventions (SMD=−0.810 [95% CI, −1.6 to 0.04]; Q0=0.0; P>.99; I2=0.0%) (see fig 8).
However, the pooled results revealed that LHA had a positive effect on disability compared with pharmacologic therapy (SMD=−0.396 [95% CI, −0.6 to −0.1]; Q1=0.668; P=.414; I2=0.0%) (see fig 8).
After 48-hour follow-up, the results demonstrated that LHA is more beneficial than pharmacologic therapy to positively affect disability (SMD=−0.472 [95% CI, −0.7 to −0.2]). However, this observation is based on only 1 study.
demonstrated that LHA is more effective than pharmacologic therapy to increase ROM after the intervention (SMD=−0.354 [95% CI, −0.6 to −0.08]; Q0=0.0; P>.99; I2=0.0%) (see fig 8).
Effects on stiffness
The pooled results indicated that LHA has a positive effect on stiffness compared with pharmacologic therapy (SMD=−0.408 [95% CI, −0.6 to −0.1]; Q1=0.045; P=.833; I2=0.0%) (see fig 8) in acute
resulting in 4 head-to-head comparisons investigated the difference between LHA and placebo/sham therapy on pain. The overall weighted mean effect showed that LHA has an positive effect compared with the control group on immediate pain reductions (SMD=−3.002 [95% CI, −5.9 to −0.07]; Q3=195.98; P<.001; I2=98.4%) (fig 9).
Fig 9Forest plot of the meta-analysis illustrating the overall weighted effect of heat application vs placebo or sham therapy. The diamonds represent the overall weighted mean ES.
Our analysis revealed that LHA has a positive immediate effect on disability compared with the control group (SMD=−1.278 [95% CI, −2.4 to −0.1]) with a high heterogeneity (Q3=50.665; P<.001; I2=94.0%) (see fig 9).
and showed that directly after LHA, muscular strength was positively affected (MD=−0.847 [95% CI, −1.6 to −0.08]; Q1=2.170; P=.141; I2=53.9%) (see fig 9).
Effects on ROM
LHA was effective compared with placebo or sham therapy to increase ROM after the intervention in 2 studies
including 4 comparisons demonstrated that LHA is superior to placebo or sham therapy to positively affect stiffness (SMD=−2.268 [95% CI, −4.2 to −0.3]; Q3=177.214; P<.001; I2=98.3%) (see fig 9).
After 48 hours, the positive effect in favor of LHA remained significant (SMD=−2.906 [95% CI, −5.6 to −0.1]) for tissure stiffness.
Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.
Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: a randomized controlled trial.
This systematic review and meta-analysis sought to investigate the effects of superficial LHA on physical and functional outcomes in individuals with any kind of musculoskeletal disorders or pain.
The main findings of the review are (1) compared with no treatment, LHA had moderate to large beneficial effects on pain relief and improved physical function immediately after application; (2) LHA resulted in significantly greater pain relief and physical function improvement compared with a standard treatment; and (3) compared with placebo or sham application there is marginal evidence that LHAs have a beneficial effect on pain relief, improving disability, and tissue stiffness.
LHA vs no treatment
LHA was effective to relieve pain in musculoskeletal disorders. The largest beneficial effects of LHA were observed in 2 studies on participants without musculoskeletal disorders, treated with local heat wraps (40°C) for 8 hours, experiencing DOMS after exercise. The studies used chemical heat wraps (using exothermic iron oxidation reaction), which are believed to act on the peripheral nervous system, whereas applications of short duration are presumed to induce pain reduction through the gate control theory in the central nervous system.
Paraspinal musculature and skin temperature changes: comparing the ThermaCare HeatWrap, the Johnson & Johnson back plaster, and the ABC Wärme-Pflaster.
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
from these authors, no effects were found regarding pain relief in participants without musculoskeletal disorders with DOMS. A possible explanation for the differences between these studies might be, that in 1 pilot study
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
The observed beneficial effects in pain relief remained significant in favor of LHA in follow-up measurements up to 48 hours. Interestingly, the studies
A pilot study using blood biomarkers and physiological parameters to assess ThermaCare heat wraps for efficacy and timing of application of reduce DOMS from exercise.
all investigating DOMS on healthy participants with a high treatment dose (40°C for 8 hours) show an overall beneficial effect for pain reductions after follow-ups of 72 hours. However, these analyses and findings are limited by the brevity of studies.
found a significant improvement in physical function after LHA compared with no treatment in patients with chronical musculoskeletal conditions. The investigated pathologies included knee osteoarthritis,
The effect of self-administered superficial local hot and cold application methods on pain, functional status and quality of life in primary knee osteoarthritis patients.
performed follow-up assessments at 48 hours where LHA continued to show a beneficial effect on physical function. These results suggest that LHA is effective in improving physical function. Further beneficial effects of LHA vs no treatment were found for muscular strength but not for QOL, ROM, or stiffness. However, the pooled results from the meta-analyses were obtained from a limited number of studies (n=2 for each outcome), which might have led to an over- or underestimation of the standardized weighted mean.
LHA vs cold
No differences were found between the effect of LHA compared with cold application in reducing pain or improving QOL. Cold gel packs (1.7°C) on the biceps,
tissue temperatures can affect conduction velocity, which might explain the immediate improved muscle function. Based on the current state of research, no conclusive results for LHA being superior to cold application were found.
LHA vs exercise
LHA compared with exercise therapy shows only beneficial effect in the studies
has a significant follow-up effect after 48 hours for pain.
LHA vs standard therapy
Immediate significant effects were found for LHAs vs standard therapy for pain reduction and improvement of physical function. A subgroup analyses for pain showed that LHA is more effective in acute compared with chronic conditions to decrease this subjective outcome. The studies
investigating LHA in acute conditions, treating patients with acute low back pain patients, showed high significant results in pain relief vs standard treatment. A comparison between acute and chronic conditions revealed that LHA is more effective in improving physical function in chronic than in acute conditions compared with standard therapy. However, these analyzed results are based on a limited number of included studies. Therefore, patients with acute nonspecific low back pain should follow the recommendations of the guidelines
Our study revealed limited findings on the effect of LHA vs pharmacologic treatment because the number of included studies was in most comparisons too low to make solid interpretations on the findings.
Nevertheless, positive effects were seen in favor for LHA on pain relief, disability, ROM, and tissue stiffness (see fig 8). Apparently, thermal treatment seems to induce changes in the mechanical characteristics of soft tissue, which might explain partially the abovementioned positive effects.
Although the results of the present study are limited, LHAs can be applied from patients by themselves, are cost-effective, and are a relatively safe or adjunct therapy form. Although some treatment guidelines do not support the use of LHA in the treatment of acute and chronic musculoskeletal disorders or pain conditions, health care providers (eg, physiotherapists) should be able to decide individually whether or not the use of LHA can be beneficial for their patients.
LHA vs placebo or sham therapy
More profound results are found in the comparison of LHA vs a placebo or sham treatment for pain relief, disability, muscular strength, ROM, and tissue stiffness (see fig 9). Regarding pain relief, the strongest results were found in the study results from Nadler et al
treating patients with acute, nonspecific low back pain with heat wraps (40°C for 8 hours for 3 days) vs an oral placebo medication. Both studies led to results favoring LHA vs placebo treatment (see fig 9). Interestingly, the effect of the LHA was higher when the treatment was conducted during the day. Although the authors
state that impaired sleep plays a strong role during recovery from illness and injury. LHA during the day seems to have a larger pain-relieving effect. LHA in combination with daily activity seems to be superior in pain relief compared with passive LHA during the night.
There were large limitations within the current evidence base on the effectiveness of LHA. The overall study quality of the review was low, and we were unable to meaningfully subgroup the included studies into high and low quality. The included studies demonstrated a moderate to high heterogeneity, and most studies had an unclear or high RoB in terms of allocation concealment, blinding of participants and personnel, blinding of outcome assessment, and selective reporting. From a limited number of studies, central tendencies and variations were extracted manually from figures. Although this was undertaken by 2 independent researchers with inconsistencies checked by a third reviewer to achieve consensus, it still serves as an estimation of treatment effect. Overall, the limited number of outcomes, especially in the subgroup analyses and the poor quality of evidence, means that results should be interpreted with caution.
Summary of the evidence
The present study focusses on topical LHA as a treatment for impaired physical function parameters of acute and chronic musculoskeletal disorders or pain.
Our results implicate that LHAs have in general a positive immediate effect on pain compared with no treatment, standard therapy, pharmacologic therapy, and placebo/sham therapy. LHA immediately increased physical function compared with no treatment and standard care, and improvements in disability were higher in the LHA group vs the groups receiving pharmacologic therapy or placebo/sham therapy. Based on the results of 2 studies, an immediate effect in favor of LHA on QOL was found compared with exercise therapy.
LHA was in general beneficial to immediately restore ROM and stiffness compared with pharmacologic therapy and placebo/sham therapy. Marginal evidence for restored muscular strength after LHA treatments compared with no treatment, cold treatments, and pharmacologic treatments was found.
Study limitations
Despite the abovementioned positive effects of LHA, the included studies demonstrate a high heterogeneity regarding included population, outcome assessment, and treated pathologies. For the included studies, insufficient data reporting was a major issue, not only for the methodological quality assessment but also for data extraction when results were presented graphically only. Further, numeric rating scales and self-reporting questionnaires were widely applied to evaluate physical and functional outcome parameters, which may have led to potential under- or overestimation of the outcome results. Another limitation is that the results of this meta-analysis are mostly based on a low number of included studies with a high risk of performance and detection bias, especially in the follow-up analyses.
Nevertheless, LHA can be applied from patients by themselves, are cost-effective, and are a relatively safe or adjunct therapy form to reduce pain and improve physical function, ROM, and tissue stiffness. Although some treatment guidelines do not support the use of LHA in the treatment of acute and chronic musculoskeletal disorders or pain conditions, health care providers (eg, physiotherapists) should be able to decide individually whether or not the use of LHA can be beneficial for their patients.
Therefore, the results cannot be transferred to other heat application methods. Duration, frequency, and temperature range of LHA treatment might also have affected the studies’ outcomes. Future high-quality randomized controlled trial studies should focus on data reporting and variation of application types and frequencies of LHA in the management of musculoskeletal disorders.
Conclusions
In conclusion, LHA is a commonly used treatment modality to reduce the symptoms of various musculoskeletal disorders. The current evidence base suggests that LHA is more beneficial than no treatment and standard care to reduce pain and to improve physical function. Some evidence is available that LHA is more effective to restore ROM and stiffness than pharmacologic therapy and placebo/sham therapy. These results could be of interest for physiotherapists, health care practitioners, and exercise physiologists alike. The effects favoring LHA seem to be most likely present in acute conditions compared with chronic conditions.
Regarding follow up effects, the findings are based on a limited number of studies, which makes a meaningful interpretation difficult. Because of heterogeneity of methodologies used and unclear risk of bias the included studies, the effectiveness of LHA remains relatively unclear. In this research area high-quality well-reported research is required.
Supplier
a.
CMA II; Biostat Inc.
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