Abstract
Purpose: The purpose of this study is to compare the reliability of varying intertrial rest periods of three grip strength measurements using the average value of three trials, the maximum value of three trials, and the value of one trial (the first value of the three trials). It will also clarify how to interpret such values in the clinic.
Methods: We conducted three sessions of tests using varying intertrial rest periods (15 seconds, 30 seconds, 60 seconds) for grip strength measurement on 40 healthy adult male and 40 healthy adult female participants. Data were divided into average value, maximum value of three trials, and the value of one trial (the first value of three trials), and reliability, systematic error, and minimal detectable change (MDC) were calculated.
Results: The maximum value of the three trials had the highest reliability and no systematic error was
observed. The average value of the three trials showed a fixed bias, and the values tended to rise as the
intertrial rest period between trials lengthened. MDC was 5.26 to 8.41 kg (12.5 to 21.4%) for males and 3.56 to 5.22 kg (15.2 to 20.1%) for females.
Discussion: Under the conditions of this study, the maximum value of the measurements of the three trials is the most reliable and its use is recommended. In this case, as a general guideline, a change of 20% or more from the measured value can be used as a criterion for a true change (improvement or worsening).
