Spring-loaded body mass equivalent horizontal reactive countermovement jump ground contact and flight times, but not peak forces, are comparable to vertical jumping

摘要

Horizontal (cylinder-based) sledge jumping has been shown to ameliorate multi-system deconditioning induced by long-term bed-rest. However, biomechanics differ from 1 g vertical jumping, in particular prolongation of ground contact times (GCT), reduction of peak force, rate of force development (RFD) (and presumably stretch shortening cycle [SSC] efficacy) and stiffness, whilst also requiring relatively complex equipment. Thus, we sought to determine if horizontal spring-loaded countermovement jumps were more analogous to vertical jumping. 9 healthy (5 female) subjects (27 7yrs; 169.0 5.3 cm; 63.6 2.6 kg) performed 10 reactive countermovement jumps vertically, and horizontally (randomized) when lay on a spring-loaded carriage per formed against loading (at lift-off) equivalent (+/- 6%) to their body weight. Jump kinetics, kinematics and lower limb/trunk electromyographic activity were compared between conditions (paired t-tests). Mean flight and GCTs did not differ, however, peak jump height (p = 0.003; d =-0.961) was greater when jumping horizontally. In contrast, ground reaction forces (zGRF) during take-off (p 2020 Published by Elsevier Ltd.