Electromyographic Analysis of Conventional and Rubber-Based Band Squats
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The purpose of this study was to analyze mean I-EMG activity of the vastus lateralis and the hamstrings group during the back squat exercise using three different types of resistances. Subjects: Twenty-two healthy, physically active collegiate males with at least 6 months of resistance training experience using the back squat exercise served as subjects for this study. Measurements: To evaluate maximal strength on the squat exercise, 3 1RMs were required from every subject, one for each resistance condition. The purpose of this initial testing was to assign an appropriate external load relative to each subject's one-repetition maximum (1RM) for the No Band (NB), Bottom Band (BB), and Top Band (TB) conditions. EMG testing was then conducted using a 2-channel electromyography (EMG) system that analyzed muscle activity from the vastus lateralis and the hamstrings during the squat exercise for each resistance condition. Mean integrated-EMG values were then collected for the 90 and 10% intervals for each phase and expressed as mean arbitrary units. Results: There was a significantly greater 1RM for the BB condition compared to either the TB or NB conditions. Also, there was a significantly greater 1RM for the TB condition compared to the NB condition. For the vastus lateralis, repeated measures ANOVA indicated a significantly lower mean I-EMG output in the eccentric versus concentric contractions. Also, a significantly lower vastus lateralis mean I-EMG output was observed at the 90% interval of displacement compared to the 10% interval of displacement. Post-hoc analysis indicated that at the 90% interval of displacement there was a significantly lower vastus lateralis mean I-EMG output in the NB condition than both the BB and TB conditions. At the 10% interval of displacement for the vastus lateralis, no significant differences among any of the band configurations were observed. For the hamstrings muscle group, repeated measures ANOVA again indicated a significantly lower mean I-EMG output for eccentric versus concentric contractions. A significantly higher mean hamstring I-EMG output was observed at 90% compared to 10% intervals of displacement. Post-hoc analysis indicated for the hamstrings group that at the 90% interval of displacement, no significant differences among band conditions were observed. In contrast, at the 10% interval of displacement there was a significantly higher mean hamstring I-EMG output in the NB condition than the BB condition. Conclusion: These results indicate that during a given repetition of the squat exercise, greater overall muscle activity can be obtained by performing BB or TB squats as opposed to a conventional squat without bands (NB). A greater amount of muscle stimulation per repetition could ultimately enhance greater strength adaptations to occur over time during training.