The effects of bar positioning, stance width, repetition, and load on muscle activity during the barbell back squat.

The barbell back squat is used widely across multiple sporting disciplines as part of strength and conditioning training. There are multiple training variations within performing a BBS. The hypothesis of this study was that bar positioning (high bar versus low bar), stance width (wide stance versus narrow stance), weight, and the number of repetitions completed (light weight - ten repetitions at 50% of maximum; heavy weight - three repetitions at 80% of maximum) can be manipulated for targeted training effects. The aim of the study was to quantify the effect squatting technique has on the activation of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, semitendinosus, gastrocnemius and gluteus maximus. Surface electromyography and kinematic data were recorded from eighteen healthy participants (twelve male, six female). Mean total area under the activation curve was compared for each muscle. Adopting a wide stance width showed increases in both peak and cumulative activation of the vastus medialis (p < 0.015). Squatting with increased weight showed increased cumulative activation of the vastus lateralis and semitendinosus (p < 0.041). An increased peak activation of the biceps femoris was observed when a high bar and wide stance technique was performed with a heavy weight compared to a light weight (p = 0.047). A narrow stance squat showed a 3.7° increase in peak knee flexion (p = 0.010) and a decrease of 8.2° of hip abduction (p < 0.001). A low bar position revealed increased hip flexion of 3.4° (p = 0.012). Overall, consistent muscle activations did not favour any combination of squat parameters. Athletes wishing to increase strength may choose one of several combinations of squat stance, bar positioning, and weight-to-repetition ratios, guided by what is most comfortable for the athlete.