Abstract
Background and Purpose: Dynamic handgrip strength endurance is essential for daily activities that require repetitive gripping movements for a sustained period. At this time, there is no information about the reliability of measurement of dynamic handgrip strength endurance in older individuals. Thus, the purpose of this study was to investigate the test-retest reliability of dynamic handgrip strength endurance in older women.
Methods: A cross-sectional study was performed. Thirty older women aged 70.5 (3.6) years performed 2 assessment sessions (test and retest), separated by 3 days. During these sessions, the dynamic handgrip strength endurance was evaluated using a testing protocol consisted of 12 repeated maximal isometric contractions for 3 seconds, with a 5-second rest between contractions (repetitions). The maximal handgrip strength at each repetition (repeated maximal repetitions) was evaluated in both hands (preferred and nonpreferred hand) using an hydraulic dynamometer Jamar; while the percentage change (using the mean of the first and the last 3 repetitions as well as the mean of the first and the last 6 repetitions) and the fatigue index were calculated.
Results: The test-retest reliability for the assessment of repeated maximal repetitions (intraclass correlation coefficient [ICC] = 0.82-0.95, standard error of measurement [SEM] = 0.76-1.22 kg, SEM 95% confidence interval [CI] = 0.53-1.69 kg, SEM% = 3.6-8.6) and of percentage change (ICC = 0.81-0.87, SEM = 3.26%-4.40%, SEM 95% CI = 2.23-6.33%, SEM% = 3.4-4.7) was found to be high, whereas fatigue index exhibited lower reliability (ICC = 0.69-0.84, SEM% = 10.9-11.8).
Conclusion: A dynamic protocol of 12 repeated maximal repetitions may be used for the evaluation of dynamic handgrip strength endurance, using the repeated maximal repetitions and the percentage change as the most reliable indicators for the determination of muscle endurance. However, the assessment of fatigue index should be interpreted with more caution.