Effect of Visual Feedback on Muscle Endurance in Normal Subjects

The measurement of maximum voluntary isokinetic contraction is a common practice in research and clinical settings. The purpose of this study was to investigate the effect of visual feedback on muscle endurance. Subjects were 22 male, between the ages of 18 and 31. Each subject had no history of lower extremity joint injury, surgery, or disease. All subjects completed two isokinetic exercise test sessions. The tests consisted of 50 maximum voluntary isokinetic contractions, using dynamometer (KIN-COM500H) at 90 degrees per second. All left lower extremities were measured. On endurance and effects fatigue index of visual feedback and no visual feedback were compared about every tenth average peak torque. On comparisions between with and without visual feedback were analyzed using a paired t-test. On average between 11th and 20th repetitions, average peak torque with visual feedback was significantly greater than without visual feedback (p<0.05). Excepting average torque between 11th and 20th repetition the results indicated no significant difference between with and without visual feedback. The fatigue index with feedback was not significantly different from that without visual feedback. These results suggest that visual feedback does not influence the fatigue index in measurements of muscle endurance.