BACKGROUND: Biofeedback exercises are among the frequently used methods to increase muscle strength and proprioception. However, no previous study investigating the effects of exercises performed with the biofeedback mode of an isokinetic dynamometer on muscle strength, proprioception and balance, could be traced. The aim of the study was to explore the effects of exercises performed in the biofeedback mode of an isokinetic dynamometer with their isotonic counterparts on muscle strength, balance, and proprioception. METHODS: Ninety-five participants were included in this prospective case control study. Isometric and isokinetic muscle strength test, biofeedback test, Y-balance test, active and passive proprioception measurements of the study participants were performed. Three experimental groups (IT-IT group: isotonic exercises, IT-BF group: isotonic and biofeedback exercises, BF-BF group: biofeedback exercises) were made to perform 10 sessions of exercises (IT-IT group: 3x10 repetition, 2 sets isotonic exercises; IT-BF group: 3x10 repetition isotonic exercises and 3x60 sec biofeedback exercises; BF-BF group: 3x60 sec 2 sets biofeedback exercises/strength [50% MVC for the quadriceps muscle with the help of an isokinetic dynamometer]). No intervention was performed in the control group. RESULTS: After the exercise program in all groups to which the exercise protocol was applied, a statistically significant improvement was found in quadriceps strength, balance, and proprioception results (P<0.05). The Y-balance test and proprioception final measurement of the BF-BF group were significantly higher compared to the other three groups (IT-IT group, IT-BF group and control group), and the most significant improvement was observed in the BF-BF group (P<0.05). CONCLUSIONS: The exercise performed in the biofeedback mode of an isokinetic dynamometer made significant contributions to the simultaneous improvement in the three parameters of physical fitness. Based on all these data, exercises performed in the biofeedback mode are possibly superior to conventional isotonic exercise practices.