EFFECT OF PRACTICE CONTRACTIONS ON GRIP STRENGTH

PURPOSE: This study investigated the effects of different types of practice contractions on a series of maximal grip strength measurements and the mean of the first three measurements. SUBJECTS: Subjects were 12 males and 6 females (mean age, 20.4 [+ or -] 1.3 years) without impairments of their upper extremities. METHODS AND MATERIALS: A standard Jamar hand dynamometer was used for the practice contractions and the grip strength measurements. Subjects were measured during three sessions with at least 72 hours between sessions. During each session they were measured during six contractions (trials) of each hand in a standardized position (0 [degrees] shoulder flexion, adduction, rotation; 90 [degrees] elbow flexion; wrist in neutral position). They performed different types of randomly assigned practice trials during the three sessions. One session included three submaximal practice trials at 25%, 50%, and 75% of their maximal effort. Another session included one maximal practice trial. A third session did not include practice trials. A one-minute rest period was allotted between trials. ANALYSES AND RESULTS: The data were analyzed using a three-factor analysis of variance with repeated measures on all factors (hand, practice, and trials). When using the mean of each subject's first three trials, the data were analyzed using a two-factor analysis of variance with repeated measures on both factors (hand and practice). The level of significance was 0.05. Post-hoc analyses were used when significant differences were found. The analyses demonstrated significant differences in the main effect of hand with the dominant hand's measurements significantly higher than the nondominant measurements. For the three-factor analysis, there was a significant difference for the main effect of trials. The first and second trials were significantly higher than the other trials. For the two-factor analysis, the means of the first three trials were not significantly different between the sessions. There were no significant difference for the main effect of practice. There were no significant interactions. CONCLUSION: After a session of submaximal, maximal, or no practice contractions, maximal grip strength measurements of young adults without impairments of their upper extremities did not differ significantly between sessions.