The inter-segmental covariation of landing from a countermovement jump in microgravity

Details

Supervisors

Schepens, Bénédicte ; Toussaint, Thibaut

Faculty

Faculté des sciences de la motricité

Degree label

Master [120] en sciences de la motricité, orientation générale, à finalité spécialisée: kinésithérapie musculo-squelettique

Abstract

Purpose: The purpose of this study is to describe the intersegmental coordination of landing from a CMJ in a 0 g environment, highlighting the potential effect of different simulated microgravity levels (0.2 g0, 0.4 g0, 0.6 g0, 1.0 g0) and the potential effect of the 0 g environment (1.0 g0 in the 0 g environment vs 1.0 g in the laboratory) on such coordination. Methods: Eight subjects performed countermovement jumps in weightlessness at 0.2, 0.4, 0.6, and 1.0 g. Simulated microgravity was obtained during parabolic flights reproducing a 0 g environment using a subject loading system, which applied a pull-down force to the body. The elevation angles (EA) of four segments (foot, shank, thigh, trunk) were calculated and a Principal Component Analysis was performed on their temporal waveforms. List of findings: 1) Landing from a CMJ can be described by a law of intersegmental covariation, which can be applied also in weightlessness under various simulated microgravity levels (0.2, 0.4, 0.6, and 1.0 g0). The CNS proved able to perceive the sensory (proprioceptive and otolithic) perturbations and adapt the motor control of landing accordingly in all experimental conditions. 2) The CNS appears to tune the movement of the four body segments (foot, shank, thigh, trunk) focusing on the modular control of the flexion-extension cycle of the entire body. However, the human motor control of landing remains better optimised for Earth gravity. 3) The thigh is the predominant factor in the coordination of landing, followed by the shank, trunk, and foot segments. 4) In weightlessness, the foot touches the ground in a flatter position, offering better stability during the landing task. 5) In microgravity, due to decreased loads that need to be dispersed, the shank and trunk segments are more erect at touch-down.