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PURPOSE: The purpose of this study was to examine the effects of positive and negative verbal feedback on forearm grip strength associated with central nervous system activity between men and women. METHODS: A pair of EMG electrodes were placed on the flexor carpi radialis and the extensor digitorum muscles of the subject's dominant forearm. Participants performed four 3 s trials of a maximal grip task with 2 min of rest between each trial. The first trial was for familiarization and the second was a control following no verbal feedback. The third and fourth trials were randomized between participants and were preceded with negative or positive feedback regardless of force generation. The change in the integrated EMG activity over a 1 s interval surrounding peak force was calculated. RESULTS: For all subjects, grip force was significantly different among the experimental conditions (F=21.9, p<0.001). Furthermore, positive and negative feedback were both greater than the control condition with a mean increase of 22.7 ± 6.1 N (p<0.01), and 44.4 ± 7.8 N (p<0.001), respectively. The force generated during the negative feedback condition was also 21.7 ± 6.1 N (p<0.01) greater than the positive feedback condition for all subjects. For females, when compared to the control condition, grip force increased significantly by 21.1 + 7.1 N (p<0.05) following positive feedback and increased significantly by 28.2 + 8.0 N (p<0.01) following negative feedback. However, there was no significant difference between the positive and negative feedback conditions (p=0.54). For males, when compared to the control condition, there was a none-significant increase in grip force after positive feedback of 24.5 + 10.5 N (p=0.09), but there was a significant increase of 63.1 + 12.9 N (p<0.001) after negative feedback. For all subjects, there were no significant differences in the integrated EMG for flexors or extensors among the experimental conditions. CONCLUSION: Both positive and negative verbal feedback can be used to increase grip force, but there may be sex-related differences. These results indicate the type of feedback given during testing of grip strength affects the test results differently for males than females and therefore standardization of feedback provided during testing is warranted.

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