Effect of visual feedback and verbal encouragement on concentric quadriceps and hamstrings peak torque of males and females

The purpose of this study was to determine the effect of visual feedback and verbal encouragement on concentric peak torque of the quadriceps and hamstrings muscles of males and females at an isokinetic velocity of 60 deg/s. All testing was performed on the Biodex B-2000 isokinetic dynamometer in three sessions, separated by 7 to 14 days. Fifteen males and 15 females (age = 25.4 +/- 2.4 yrs, wt = 76.6 +/- 16.5 kg, ht = 173.61 +/- 9.5 cm) were tested under the following conditions: (a) visual feedback, (b) verbal encouragement, (c) combined visual feedback and verbal encouragement, and (d) no feedback (control). Testing order was counterbalanced to control for possible learning effects. Two separate 2 x 4 repeated measure analyses of variance (ANOVA) were used to examine the difference among test conditions. Examination of quadriceps force production revealed that subjects generated greater peak torque when visual feedback was provided than when verbal encouragement or no feedback were provided. Similarly, quadriceps force production was greater when combined visual feedback and verbal encouragement was provided than when verbal encouragement or no feedback were provided (p < 0.05). Examination of hamstrings force production revealed that subjects generated greater peak torque when combined visual feedback and verbal encouragement was provided than when verbal encouragement, and no feedback were provided. Additionally, hamstrings force production was greater when visual feedback was provided than when no feedback was provided (p < 0.05). These results indicate that the use of visual and combined visual and verbal feedback increased quadriceps and hamstrings force production when compared to the control condition where no feedback was provided.