| Abstract | This investigation analyzed neuromuscular recruitment patterns with and without the presentation of velocity-based biofeedback during a set of back squats to fatigue. This study followed a repeated-measures, randomized design in which each participant served as his own control completing all four experimental conditions. Subjects performed the back squat exercise to fatigue with and without biofeedback at 75% one-repetition maximum (1RM). During the biofeedback trials, a screen was placed in front of subjects during the exercise that provided real-time velocity feedback for each repetition. In these trials, participants were instructed to "explode out" of the bottom of the squat as to try and "beat" the previous velocity measurement with each subsequent repetition. Surface electromyography (EMG) was used to measure electrical activity during muscular contractions. Electrodes were placed along the bellies of the vastus lateralis (VL), gluteus medius (GM), and biceps femoris (BF) bilaterally. For the purpose of this paper, data pertaining to the subjects' right side during the 75% 1RM trials will be analyzed and discussed. There was no main effect for condition for any of the muscles examined (p > 0.05). Further, no significant interaction with condition (biofeedback or no-biofeedback) was observed for any of the muscles examined (p > 0.05). A main effect for time of repetition (first, last) was observed for all three muscles (VL, p = 0.001; BF, p = 0.027; GM, p = 0.024). Results suggest that higher EMG values are observed during fatigue, but no differences exist with the presence of biofeedback. |
