Abstract
The purpose of this study was to compare and contrast the kinetics and kinematics of squat and step-up performance in well-trained athletes. Triaxial ground reaction force (GRF) and 3D kinematic data were collected in 4 maximal effort repetitions each at 70, 80, and 90% of 1 repetition maximum (1RM) of squat and step-up. The difference in concentric phase kinetics and kinematics between the squat and step-up was compared using effect sizes (ES +/- 90% confidence limits [CLs]) classified as: less than 0.2 as trivial; 0.2-0.6 as small; 0.6-1.2 as moderate; and 1.2-2.0 as large. Where the 90% CL crossed negative and positive 0.2 values, the effect was considered "unclear.n Ground reaction force was higher for the step-up than squat at all relative intensities per leg (peak GRF ES: 2.56 +/- 0.19 to 2.70 +/- 0.37; average GRF ES: 1.45 +/- 0.27 to 1.48 +/- 0.29). Per leg, the difference in concentric impulse favored the step-up compared with squat at 70% 1RM (ES = 0.71 +/- 0.40) and 80% 1RM (ES = 0.30 6 0.41) but was unclear at 90% 1RM (ES = 20.25 +/- 0.47). The squat peak velocity was greater compared with step-up at all intensities (ES = 21.74 +/- 0.48 to 21.33 +/- 0.48). Despite a lower external load and a single base of support, per leg, the step-up produced comparable GRF because the squat suggesting overload provided by the step-up is sufficient for maximal strength development. Future research may investigate the efficacy of the step-up in a training intervention for the development of lower-body strength.