Improving Posterior Chain Engagement and Forward Trunk Lean During The Front Squat

Abstract

Front squats are a commonly used squat variation as they place less load on the lumbar spine. However, when done incorrectly, front squats may have inefficient posterior-chain activation and reduced trunk stability, thus negating any potential benefits. Various techniques have been proposed to mitigate such consequences but, to date, few have been quantified. PURPOSE: This study examined the effects of an intervention designed to increase posterior chain engagement on kinematics and muscle activity during the front squat. METHODS: 7 physically active adults (4 male, 3 female; ages 25 +/- 4 years) performed front squats under two conditions: baseline and after instruction in a specific front squat technique emphasizing foot alignment and using EMG biofeedback to help engage the glutes. All squats were performed at 70% of a tested 1 rep max. Whole-body kinematics were recorded with a 12-camera motion capture system while ground reaction forces were measured using two force plates. Peak hip extensor moments, pelvic tilt, and forward torso lean were calculated on each repetition. Activity of the erector spinae (ES) and gluteus maximus (GM) muscles was analyzed by calculating average root mean square (RMS) amplitude across the squat. Differences from pre to post intervention were evaluated using paired t-tests and effect sizes. RESULTS: Peak pelvic tilt, forward trunk lean, and hip extensor moments were all not statistically different after the intervention and all showed small effect sizes (Table 1). While mean ES activity decreased after the intervention the effect size was small (Table 1). In contrast, while mean GM activity was not significantly different post-intervention, there was a moderate effect size (Table 1).Table 1: Means (± standard deviations) pre and post intervention.CONCLUSION: The intervention technique changed activation of some posterior muscle groups, but not kinematics or kinetics. Whether this was due to the intervention itself or participants requiring more training time requires further investigation.