Original article| Volume 93, ISSUE 11, P2035-2041, November 2012

Reliability and Validity of a Low Load Endurance Strength Test for Upper and Lower Extremities in Patients With Fibromyalgia

Published:February 27, 2012DOI:


      Munguía-Izquierdo D, Legaz-Arrese A. Reliability and validity of a low load endurance strength test for upper and lower extremities in patients with fibromyalgia.


      To evaluate the reliability, standard error of the mean (SEM), clinical significant change, and known group validity of 2 assessments of endurance strength to low loads in patients with fibromyalgia syndrome (FS).


      Cross-sectional reliability and comparative study.


      University Pablo de Olavide, Seville, Spain.


      Middle-aged women with FS (n=95) and healthy women (n=64) matched for age, weight, and body mass index (BMI) were recruited for the study.


      Not applicable.

      Main Outcome Measures

      The endurance strength to low loads tests of the upper and lower extremities and anthropometric measures (BMI) were used for the evaluations. The differences between the readings (tests 1 and 2) and the SDs of the differences, intraclass correlation coefficient (ICC) model (2,1), 95% confidence interval for the ICC, coefficient of repeatability, intrapatient SD, SEM, Wilcoxon signed-rank test, and Bland-Altman plots were used to examine reliability. A Mann-Whitney U test was used to analyze the differences in test values between the patient group and the control group. We hypothesized that patients with FS would have an endurance strength to low loads performance in lower and upper extremities at least twice as low as that of the healthy controls.


      Satisfactory test-retest reliability and SEMs were found for the lower extremity, dominant arm, and nondominant arm tests (ICC=.973–.979; P<.001; SEMs=1.44–1.66 repetitions). The differences in the mean between the test and retest were lower than the SEM for all performed tests, varying from −.10 to .29 repetitions. No significant differences were found between the test and retest (P>.05 for all). The Bland-Altman plots showed 95% limits of agreement for the lower extremity (4.7 to –4.5), dominant arm (3.8 to –4.4), and nondominant arm (3.9 to –4.1) tests. The endurance strength to low loads test scores for the patients with FS were 4-fold lower than for the controls in all performed tests (P<.001 for all).


      The endurance strength to low loads tests showed good reliability and known group validity and can be recommended for evaluating endurance strength to low loads in patients with FS. For individual evaluation, however, an improved score of at least 4 and 5 repetitions for the upper and lower extremities, respectively, was required for the differences to be considered as substantial clinical change. Patients with FS showed impaired endurance strength to low loads performance when compared with the general population.

      Key Words

      List of Abbreviations:

      BMI (body mass index), CI (confidence interval), ICC (intraclass correlation coefficient), FS (fibromyalgia syndrome), SEM (standard error of the mean)
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Archives of Physical Medicine and Rehabilitation
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Wolfe F.
        • Smythe H.A.
        • Yunus M.B.
        • et al.
        The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia.
        Arthritis Rheum. 1990; 33: 160-172
        • Goldenberg D.L.
        Fibromyalgia, chronic fatigue syndrome, and myofascial pain syndrome.
        Curr Opin Rheumatol. 1997; 9: 135-143
        • Munguía-Izquierdo D.
        • Legaz-Arrese A.
        Exercise in warm water decreases pain and improves cognitive function in middle-aged women with fibromyalgia.
        Clin Exp Rheumatol. 2007; 25: 823-830
        • Gormsen L.
        • Rosenberg R.
        • Bach F.W.
        • Jensen T.S.
        Depression, anxiety, health-related quality of life and pain in patients with chronic fibromyalgia and neuropathic pain.
        Eur J Pain. 2010; 14: 127.e1-127.e8
        • Verbunt J.A.
        • Pernot D.H.
        • Smeets R.J.
        Disability and quality of life in patients with fibromyalgia.
        Health Qual Life Outcomes. 2008; 6: 8
        • Walker J.G.
        • Littlejohn G.O.
        Measuring quality of life in rheumatic conditions.
        Clin Rheumatol. 2007; 26: 671-673
        • Aparicio V.A.
        • Ortega F.B.
        • Heredia J.M.
        • et al.
        Handgrip strength test as a complementary tool in the assessment of fibromyalgia severity in women.
        Arch Phys Med Rehabil. 2011; 92: 83-88
        • Munguía-Izquierdo D.
        • Legaz-Arrese A.
        Assessment of the effects of aquatic therapy on global symptomatology in patients with fibromyalgia syndrome: a randomized controlled trial.
        Arch Phys Med Rehabil. 2008; 89: 2250-2257
        • Panton L.B.
        • Kingsley J.D.
        • Toole T.
        • et al.
        A comparison of physical functional performance and strength in women with fibromyalgia, age- and weight-matched controls, and older women who are healthy.
        Phys Ther. 2006; 86: 1479-1488
        • Valkeinen H.
        • Häkkinen A.
        • Alen M.
        • Hannonen P.
        • Kukkonen-Harjula K.
        • Häkkinen K.
        Physical fitness in postmenopausal women with fibromyalgia.
        Int J Sports Med. 2008; 29: 408-413
        • Lindh M.H.
        • Johansson G.A.
        • Hedberg M.
        • Grimby G.L.
        Studies on maximal voluntary muscle contraction in patients with fibromyalgia.
        Arch Phys Med Rehabil. 1994; 75: 1217-1222
        • Mannerkorpi K.
        • Svantesson U.
        • Carlsson J.
        • Ekdahl C.
        Tests of functional limitations in fibromyalgia syndrome: a reliability study.
        Arthritis Care Res. 1999; 12: 193-199
        • Pankoff B.A.
        • Overend T.J.
        • Lucy S.D.
        • White K.P.
        Reliability of the six-minute walk test in people with fibromyalgia.
        Arthritis Care Res. 2000; 13: 291-295
        • Mokkink L.B.
        • Terwee C.B.
        • Patrick D.L.
        • et al.
        The COSMIN checklist for assessing the methodological quality of studies on measurement properties of health status measurement instruments: an international Delphi study.
        Qual Life Res. 2010; 19: 539-549
        • American Psychiatric Association
        Diagnostic and Statistical Manual of Mental Disorders.
        4th ed. American Psychiatric Association, Washington (DC)1994
        • Rodríguez F.A.
        Versión española del cuestionario de aptitud para la actividad física (C-AAF/rPAR-Q).
        Arch Med Deporte. 1996; 51: 63-68
        • Thomas S.
        • Reading J.
        • Shepard R.J.
        Revision of the Physical Activity Readiness Questionnaire (PAR-Q).
        Can J Sport Sci. 1992; 17: 338-345
        • Mengshoel A.M.
        • Vøllestad N.K.
        • Førre O.
        Pain and fatigue induced by exercise in fibromyalgia patients and sedentary healthy subjects.
        Clin Exp Rheumatol. 1995; 13: 477-482
      1. Lohman T.G. Roche A.F. Martorell R. Anthropometric standardization reference manual. Human Kinetics, Human Champaign1988
        • Shrout P.
        • Fleiss J.
        Intraclass correlations: uses in assessing rater reliability.
        Psychol Bull. 1979; 86: 420-428
        • De Vet H.C.
        • Terwee C.B.
        • Knol D.L.
        • Bouter L.M.
        When to use agreement versus reliability measures.
        J Clin Epidemiol. 2006; 59: 1033-1039
        • Atkinson G.
        • Nevill A.M.
        Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine.
        Sports Med. 1998; 26: 217-238
        • Portney L.G.
        • Watkins M.P.
        Foundations of clinical research: applications to practice.
        3rd ed. Pearson Prentice Hall, Upper Saddle River2009
        • Giraudeau B.
        • Mary J.Y.
        Planning a reproducibility study: how many subjects and how many replicates per subject for an expected width of the 95 percent confidence interval of the intraclass correlation coefficient.
        Stat Med. 2001; 20: 3205-3214
        • Bland J.M.
        • Altman D.G.
        Statistical methods for assessing agreement between two methods of clinical measurement.
        Int J Nurs Stud. 2010; 47: 931-936
        • Sañudo B.
        • Galiano D.
        Using cardiovascular parameters and symptom severity to prescribe physical activity in women with fibromyalgia.
        Clin Exp Rheumatol. 2009; 27: S62-S66
        • Nordenskiöld U.M.
        • Grimby G.
        Grip force in patients with rheumatoid arthritis and fibromyalgia and in healthy subjects: a study with the Grippit instrument.
        Scand J Rheumatol. 1993; 22: 14-19
        • Borman P.
        • Celiker R.
        • Hasçelik Z.
        Muscle performance in fibromyalgia syndrome.
        Rheumatol Int. 1999; 19: 27-30
        • Bland J.M.
        • Altman D.G.
        Measurement error.
        BMJ. 1996; 313: 744
        • Rooks D.S.
        • Silverman C.B.
        • Kantrowitz F.G.
        The effects of progressive strength training and aerobic exercise on muscle strength and cardiovascular fitness in women with fibromyalgia: a pilot study.
        Arthritis Rheum. 2002; 47: 22-28
        • Valim V.
        • Oliveira L.
        • Suda A.
        • et al.
        Aerobic fitness effects in fibromyalgia.
        J Rheumatol. 2003; 30: 1060-1069
        • Gowans S.E.
        • deHueck A.
        • Voss S.
        • Silaj A.
        • Abbey S.E.
        • Reynolds W.J.
        Effect of a randomized, controlled trial of exercise on mood and physical function in individuals with fibromyalgia.
        Arthritis Rheum. 2001; 45: 519-529
        • Mannerkorpi K.
        • Nyberg B.
        • Ahlmén M.
        • Ekdahl C.
        Pool exercise combined with an education program for patients with fibromyalgia syndrome.
        J Rheumatol. 2000; 27: 2473-2481
        • Altan L.
        • Bingol U.
        • Aykac M.
        • Koc Z.
        • Yurtkuran M.
        Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
        Rheumatol Int. 2004; 24: 272-277
        • Jones C.J.
        • Rikli R.E.
        • Beam W.
        A 30-s chair-stand test as a measure of lower body strength in community-residing older adults.
        Res Q Exerc Sport. 1999; 70: 113-119
        • Rikli R.E.
        • Jones C.J.
        Development and validation of a functional fitness test for community-residing older adults.
        J Aging Phys Act. 1999; 7: 129-161