Movement Science: Impact of Immediate Visual Feedback and Verbal Encouragement on Grip Strength

The objective of this study was to verify the impact of immediate visual feedback and verbal encouragement on grip strength in two populations: healthy adults and older adults with physical impairments. Grip strength was measured with a Jamar dynamometer connected to a computer system under five experimental conditions: (1) immediate visual feedback, (2) verbal encouragement with normal voice volume, (3) verbal encouragement at high voice volume, (4) immediate visual feedback combined with verbal encouragement at normal volume and (5) immediate visual feedback combined with verbal encouragement at high voice volume. Sixty-six subjects per group were evaluated under these conditions in one session. The order of the experimental conditions was randomly determined for each subject. Results showed no significant difference (p = 0.198) between the conditions for the healthy adults group, whereas a significant difference was found for the group of older adults with physical impairments (p = 0.016). Two-by-two analyses carried out for this group suggested that conditions (3) and (5), both related to verbal encouragement with high voice volume, generated higher strength (p = 0.03–0.009) than the other three conditions. However, when we applied the Bonferroni correction to avoid a type I error, no statistically significant difference was found between the conditions. Based on this study, no specific grip strength measurement condition can be recommended.