JHT READ FOR CREDIT #038 The Reliability of One vs. Three Grip Trials in Symptomatic and Asymptomatic Subjects Fiona Coldham, BSc (Hons), MSc, MCSP y Jeremy Lewis, PhD, MCSP, MMPA Hoe Lee, PhD, MSc, PG Dip, Prof Dip Physiotherapy Department Chelsea & Westminster Hospital London, UK ABSTRACT: Grip strength is used in the assessment of hand and upper limb function. Current recommendations state that taking the mean of three repeated grip trials provides more reliable results than only one trial. A repeated measures, crossover design was used. Sixty-six subjects were recruited (22 asymptomatic subjects, 22 following carpal tunnel decompression, and 22 following flexor tendon repair). Grip strength testing was performed on a Jamar dynamometer using a standardized testing protocol. Pre- and post testing pain levels were recorded using a verbal analogue scale. Each subject’s grip strength was tested four times, twice using a single trial protocol and twice using three grip trials in ran- dom order. Intraclass correlation coefficients (ICC) (2,1), 95% con- fidence intervals, and standard error of measurements were calculated. A two-tailed paired samples t-test was used to investi- gate the difference between the grip strength values obtained and the changes in verbal analogue scale. High levels of test–retest reliability (ICC $ 0.85) were found for the three methods of grip strength testing (one trial, the mean of three trials, and the best of three trials). The mean values of grip strength generated for each method of grip strength testing produced comparable results. A significant difference (p $ 0.0001) was observed in the verbal an- alogue scale scores following one trial and three in all three sample groups. Clinically acceptable levels of reliability ($0.91) were dem- onstrated by all three methods of grip strength testing other than the mean of three trials for the asymptomatic group. Distribution of the ICC results and the elevated verbal analogue scales associ- ated with three trials suggest that the use of one grip trial may be appropriate. This study suggests that one maximal trial is as reliable as and less painful than either the best of, or, mean of three trials. J HAND THER. 2006;19:318–27. Grip strength testing is commonly used both in clinical and research settings to evaluate hand and upper limb function, level of impairment, and phys- ical performance. 1–6 It is a rapid and easy test to per- form producing reliable results, which are easy to record and interpret. 7 There are various testing protocols available and the most appropriate should be chosen in light of the assessment requirements and subject involved. The use of a standardized protocol has repeatedly been shown to maximize reliability. 8,9 In the current climate of clinical governance in the United Kingdom, with the need to demonstrate clinical effectiveness, it is essential that the physio- therapy and occupational therapy professions prove the reliability of their clinical measures. 10 Reliability is one of the most basic requirements of evaluation tools and is established when it has been demon- strated that repeated measurements are consistent. 3 To enhance a tool’s reliability it is necessary to exam- ine and develop measurement protocols. Reliability and instrument precision are essential requirements to track changes in clinical practice. 11,12 The American Society of Hand Therapists (ASHT) currently recommends using the mean of three trials as it has been reported to produce more reliable SCIENTIFIC/CLINICAL ARTICLES y This study formed part of an MSc in Rehabilitation of the Upper Limb at Curtin University of Technology. This study was funded jointly by the Westminster Medical School Research Trust, the Chelsea & Westminster Medical School Research Trust, and the Chelsea & Westminster Healthcare NHS Trust Charity. This study was presented at the IFSHT congress in June 2004. Correspondence and reprint requests to Fiona Coldham, BSc, MSc, MCSP, Physiotherapy Department, Chelsea & Westminster Hospital, London SW10 9NH, UK; e-mail: <Fiona.coldham@chelwest.nhs.uk>. 0894-1130/$ – see front matter Ó 2006 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved. doi:10.1197/j.jht.2006.04.002 318 JOURNAL OF HAND THERAPY