Background It is unclear how back squat depth influences muscle activation and should be considered when designing strength training programs. Current evidence suggests this relationship is population-specific and should be examined in different populations to optimize strength training outcomes. This study examined the effect of different squat depths on muscle activation in college football players. Methods Sixteen Division II college football players performed back squat at three depths (C1 = 65°, C2 = 90°, and C3 = 115° knee flexion). During the descent and ascent phases, five-trial averages of mean gluteus maximus (GM), semitendinosus (ST), biceps femoris (BF), vastus medialis (VM), and vastus lateralis (VL) activation were calculated. Phase-specific differences were examined by calculating one-way repeated analyses of variance (a=0.05) and Bonferroni-corrected paired t-tests for post-hoc comparisons. Results Compared to C1, activation increased during C2 and C3 for the VM, VL, and BF during the descent and ascent phases. Additionally, during ascent, the greatest VM, VL, and BF activation occured during C3. Semitendinosus activation increased during C2 and C3 compared to C1 during the ascent phase, but it was not affected during the descent phase. Similarly, no GM activation changes were observed in either phase. Conclusions These findings indicate back squat depth influence on muscle activation is phase- and muscle-specific and should be considered when designing strength training programs for college football players.
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