The kinetics and kinematics of the free-weight back squat and loaded jump squat

THOMPSON, Steve, LAKE, Jason, ROGERSON, David, RUDDOCK, Alan and BARNES, Andrew (2021). The kinetics and kinematics of the free-weight back squat and loaded jump squat. Journal of Strength and Conditioning Research.

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    Abstract

    The study aim was to compare kinetics and kinematics of two, lower-body free-weight exercises,calculated from concentric and propulsion sub-phases, across multiple loads. Sixteen strength trained men performed back squat one-repetition maximum tests (1RM) (visit 1), followed by two incremental back squat and jump squat protocols (visit 2) (loads = 0% and 30-60%, back squat 1RM). Concentric and propulsion phase force-time-displacement characteristics were derived from force-plate-data and compared via analysis of variance and Hedges g effect sizes. Intra-session reliability was calculated via intraclass correlation coefficient (ICC) and coefficient of variation (CV). All dependent variables met 53 acceptable reliability (ICC > 0.7; CV < 10%). Statistically significant three-way interactions(load x phase x exercise) and two-way main effects (phase x exercise) were observed for mean force, velocity (30-60% 1RM), power, work, displacement, and duration (0%, 30-50% 1RM) (p < 0.05). A significant two way interaction (load x 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 sub-phases (p < 0.05). Ballistic, lower-body exercise produces greater kinetic and kinematic outputs than non-ballistic equivalents, irrespective of phase determination. Practitioners should therefore utilize ballistic methods when prescribing or testing lower-body exercises to maximize athlete’s force-time-displacement characteristics.

    Item Type: Article
    Uncontrolled Keywords: Sport Sciences; 1106 Human Movement and Sports Sciences; 1116 Medical Physiology
    SWORD Depositor: Symplectic Elements
    Depositing User: Symplectic Elements
    Date Deposited: 03 Nov 2021 15:12
    Last Modified: 03 Nov 2021 15:15
    URI: http://shura.shu.ac.uk/id/eprint/29271

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