Knee Kinetics During Squats of Varying Loads and Depths in Recreationally Trained Women.

Flores, V, Becker, J, Burkhardt, E, and Cotter, J. Knee kinetics during squats of varying loads and depths in recreationally trained women. J Strength Cond Res 34(7): 1945-1952, 2020-The back squat exercise is typically practiced with varying squat depths and barbell loads. However, depth has been inconsistently defined, resulting in unclear safety precautions when squatting with loads. In addition, women exhibit anatomical and kinematic differences to men, which may predispose them to knee joint injuries. The purpose of this study was to characterize peak knee extensor moments (pKEMs) at 3 commonly practiced squat depths of above-parallel, parallel, and full depths, and with 3 loads of 0 (unloaded), 50, and 85% depth-specific 1 repetition maximum (1RM) in recreationally active women. Nineteen women (age, 25.1 ± 5.8 years; body mass, 62.5 ± 10.2 kg; height, 1.6 ± 0.10 m; mean ± SD) performed squats of randomized depth and load. Inverse dynamics were used to obtain pKEMs from 3-dimensional knee kinematics. Depth and load had significant interaction effects on pKEMs (p = 0.014). Significantly greater pKEMs were observed at full depth compared with parallel depth with 50% 1RM load (p = 0.001, d = 0.615) and 85% 1RM load (p = 0.010, d = 0.714). Greater pKEMs were also observed at full depth compared with above-parallel depth with 50% 1RM load (p = 0.003, d = 0.504). Results indicate that effect of load on female pKEMs do not follow a progressively increasing pattern with either increasing depth or load. Therefore, when high knee loading is a concern, individuals must carefully consider both the depth of squat being performed and the relative load they are using.