2002 Volume 21 Issue 3 Pages 151-158
The purpose of this study was to examine the useful measurement time when evaluating static muscle endurance by comparing various parameters during sustained static gripping for 1, 3 and 6 min. Fifteen males (mean ± SD age 20.8 ± 1.3 yr, height 172.9 ± 4.6 cm, body mass 67.7 ± 5.7 kg) and fifteen females [mean ± SD age 20.2 ± 0.9 yr, height 158.5 ± 3.2 cm, body mass 55.9 ± 4.6 kg] volunteered to participate in this study. The subjects performed the sustained static maximal grip test with a sagittal and horizontal arm position for 1, 3 and 6 min on different days. Eleven force-time parameters were selected to evaluate static muscle endurance. The trial-to-trial reliability of each measurement time of sustained static maximal gripping was very high (rxy = 0.887-0.981 (1 min), 0.912-0.993 (3 min), 0.901-0.965 (6 min)). The errors of exertion values between trials were very small (below 10%). A significant correlation was found in the following parameters: the final strength and the exponential function between 1 min and 3 min, all parameters except for the time required to reach 80% of maximal grip, the regression coefficient at post-inflection between 3 min and 6 min, and the decreasing rate between all measurement times (1 min, 3 min, and 6 min). Significant differences between the measurement times were found in all parameters except for the time to 60, 70, and 80 % force decreases, and the regression coefficient of pre-inflection. There was a tendency that the longer the measurement time, the larger the decreasing force. It is suggested that for the 6 min measurement, the subjects unconsciously restrained the maximal gripping force, influenced by a psychological factor as the pain became greater. The 1 min measurement may evaluate only the remarkable decreasing phase of the decreasing force, and not evaluate the phase of an almost steady state.