The Effect of Stance Width and Anthropometrics on Joint Range of Motion in the Lower Extremities during a Back Squat

The purpose of this study was to assess whether changing the stance width has an effect on the range of motion of hip flexion, knee flexion, and ankle dorsiflexion during an unloaded back squat, and whether these joint movements are affected by anthropometric differences. Thirty-two healthy, young adults performed unloaded back squats at three different stance widths, normalized to pelvic width. Joint angles were assessed using electromagnetic motion capture sensors on the sacrum, and thigh, shank and foot of the dominant leg. ANOVA comparison of joint angles for the three stance widths, at 10° intervals of thigh orientation during the squat, indicated that joint angles tended to be larger when stance width was narrower, with the most significant effects on ankle dorsiflexion. A greater trunk/thigh length ratio (relatively long trunk) also tended to be associated with lower ankle and knee angles, while a greater thigh/shank length ratio (relatively long thigh) tended to be associated with higher ankle and knee angles, for the two narrower stance widths. The most practical implication of our findings is that individuals with limited ankle dorsiflexion, or with particularly long legs / thighs, may benefit from a wider stance width when squatting.