Supplemental Digital Content is Available in the Text. Abstract Thompson, SW, Lake, JP, Rogerson, D, Ruddock, A, and Barnes, A. Kinetics and kinematics of the free-weight back squat and loaded… Click to show full abstract
Supplemental Digital Content is Available in the Text. Abstract Thompson, SW, Lake, JP, Rogerson, D, Ruddock, A, and Barnes, A. Kinetics and kinematics of the free-weight back squat and loaded jump squat. J Strength Cond Res 37(1): 1–8, 2023—The aim of this study was to compare kinetics and kinematics of 2 lower-body free-weight exercises, calculated from concentric and propulsion subphases, across multiple loads. Sixteen strength-trained men performed back squat 1 repetition maximum (1RM) tests (visit 1), followed by 2 incremental back squat and jump squat protocols (visit 2) (loads = 0% and 30–60%, back squat 1RM). Concentric phase and propulsion phase force-time-displacement characteristics were derived from force plate data and compared using analysis of variance and Hedges' g effect sizes. Intrasession reliability was calculated using intraclass correlation coefficient (ICC) and coefficient of variation (CV). All dependent variables met acceptable reliability (ICC >0.7; CV < 10%). Statistically significant 3-way interactions (load × phase × exercise) and 2-way main effects (phase × exercise) were observed for mean force, velocity (30–60% 1RM), power, work, displacement, and duration (0%, 30–50% 1RM) (p < 0.05). A significant 2-way interaction (load × exercise) was observed for impulse (p < 0.001). Jump squat velocity (g = 0.94–3.80), impulse (g = 1.98–3.21), power (g = 0.84–2.93), and work (g = 1.09–3.56) were significantly larger across concentric and propulsion phases, as well as mean propulsion force (g = 0.30–1.06) performed over all loads (p < 0.001). No statistically significant differences were observed for mean concentric force. Statistically longer durations (g = 0.38–1.54) and larger displacements (g = 2.03–4.40) were evident for all loads and both subphases (p < 0.05). Ballistic, lower-body exercise produces greater kinetic and kinematic outputs than nonballistic equivalents, irrespective of phase determination. Practitioners should therefore use ballistic methods when prescribing or testing lower-body exercises to maximize athlete's force-time-displacement characteristics.
               
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