ORIGINAL ARTICLE Applicability and Test-Retest Reliability of Isokinetic Shoulder Abduction and Adduction in Women Fibromyalgia Patients Jose C. Adsuar, PhD, Pedro R. Olivares, PhD, Jose A. Parraca, PhD, Miguel A. Herna ´ndez-Mocholı ´, MSc, Narcis Gusi, PhD From the Faculty of Sports Sciences, University of Extremadura, Caceres, Spain. Abstract Objective: To investigate the applicability and reliability of isokinetic strength measurements during concentric and eccentric actions of the shoulder muscles in fibromyalgia (FM) patients. Design: Test-retest reliability study. Setting: University laboratory. Participants: Women with FM (NZ25) aged 37 to 69. Interventions: Not applicable. Main Outcome Measures: Two isokinetic tests of the shoulder were repeated after an interval of 7 days. Each test involved 3 repetitions of abduction and adduction performed at a rate of 60  /s. The first test involved 2 concentric muscle actions (concentric/concentric test). The second test involved concentric abduction followed by eccentric adduction (concentric/eccentric test). Unilateral peak torque (Nm) and average work (J) were measured. Applicability was calculated as the proportion of participants who were able to complete every test. Reliability was analyzed by intraclass coefficient (ICC), standard error of measurement, and smallest real difference (SRD). Results: Applicability was 84% for the concentric/concentric test and 52% for the concentric/eccentric test. The main factor influencing applicability was age. In the concentric/eccentric test, measurement of peak torque showed high reliability for the abduction (ICCZ.88; standard error of measurementZ1.82; SRDZ5.05) and adduction (ICCZ.89; standard error of measurementZ3.83; SRDZ10.62) phases. In the concentric/concentric test, measurement of peak torque showed low reliability in the abduction phase (ICCZ.29; standard error of measurementZ6.45; SRDZ17.87) and excellent reliability in the adduction phase (ICCZ.92; standard error of measurementZ5.95; SRDZ16.50). Conclusions: The applicability of shoulder isokinetic tests in FM patients who are women may be affected by age. In comparison, the concentric/ concentric test was more applicable and less reliable than the concentric/eccentric test during abduction and adduction. These findings will facilitate the clinical interpretation of changes in isometric and isokinetic shoulder adduction and abduction tests in women with FM. Archives of Physical Medicine and Rehabilitation 2013;94:444-50 ª 2013 by the American Congress of Rehabilitation Medicine Patients with fibromyaliga (FM) present with widespread musculoskeletal pain, weakness, and fatigue. 1-6 Most FM patients report difficulties in everyday activities, such as climbing stairs, running, carrying objects, and working with their arms in an elevated position. 7,8 Individuals with FM therefore tend to be untrained, and some studies have shown that they have less muscle strength in the upper and lower extremities than healthy subjects. 3,7,9,10 In the performance of daily activities, such as raising up and putting down an object, cleaning windows, hanging out clothes, and making beds, the shoulder muscles act concentrically or eccentrically to control the movement of the limb and/or prevent joint overloading. 11 Although the performance of daily activities necessitates frequent eccentric muscle action, only 2 previous studies have used eccentric contraction to evaluate isokinetic strength in FM, 11,12 and only 1 of these studies measured shoulder movements. 11 The infrequent use of tests involving eccentric muscle actions in FM research may be because these patients Supported by a predoctoral fellowship by the Spanish Ministry of Education (FPU3839); and the Government of Extremadura and European Union Regional Development Fund (ERDF- FEDER) funds (GRI0127). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. 0003-9993/13/$36 - see front matter ª 2013 by the American Congress of Rehabilitation Medicine http://dx.doi.org/10.1016/j.apmr.2012.08.198 Archives of Physical Medicine and Rehabilitation journal homepage: www.archives-pmr.org Archives of Physical Medicine and Rehabilitation 2013;94:444-50