Back squat depth influences activation of some, but not all lower limb muscles in collegiate American football players.

This article investigates how varying back squat depths affect lower limb muscle activation in Division II collegiate American football players. The study measured activation of the gluteus maximus (GM), semitendinosus (ST), biceps femoris (BF), vastus medialis (VM), and vastus lateralis (VL) at three knee flexion angles (65°, 90°, and 115°) during both descent and ascent phases of the squat. Results showed that increasing squat depth significantly increased activation of the VM, VL, and BF muscles in both phases, while ST activation increased only during ascent, and GM activation remained unchanged across depths. These findings suggest that back squat depth influences muscle activation in a phase- and muscle-specific manner and should be considered when designing strength training programs for collegiate American football players, with caution advised when generalizing to other populations.