Influence of Proprioceptive Reweighting Ability on Lower-limb Biomechanics During Functional Tasks

"The subject will be in unipodal support (only one foot on the ground) on the tested lower limb in the center of the platform. Three lines forming a Y will be arranged according to the lower limb in charge in three directions : anterior (ANT), posteromedial (PM) and posterolateral (PL). The goal is then to reach the longest distance possible in all three directions with the tip of the foot in relief before returning to the starting position. The subject will have 4 training trials per direction on each lower limb then 3 trials will be recorded in order to keep the average."

The subject will drop from a step and land on one leg, then jump as high as possible and stabilize again on the same leg. The height of the step is 30 cm. The subject will perform 3 consecutive jumps in the strictest respect of the instructions: drop to the level of the mark on the ground and bounce as high as possible while spending a minimum of time on the ground. The subject must stabilize for 3 seconds during the second contact with the ground so that the instructions and measurements are reproducible.

"The objective is to create an unanticipated playing situation, close to the daily actions of the subjects in the practice of handball. The subject will make sidestep cutting manœuvre in front of an opponent simulated by a dummy used during usual training.~The subject will sprint in a straight line and then at the force platform will make a rapid change of direction on the side of his shooting arm or will continue his run in a straight line. A light signal randomly will indicate to the player the direction in which he must carry out his manoeuvre. A computer reconstruction of the kinematics and dynamics (knee moment) will be performed."

The subject will be asked to stand, motionless in bipodal (both feet on the ground) support on a stable and unstable ground (foam). A tendon vibration (80Hz) will be randomly applied to the subject in the Achilles tendons or paravertebral muscles. This vibration will cause an alteration of proprioceptive information in the vibrated area leading to a disruption of postural balance. Thus, according to the amount of displacement of the center of pressure (CoP), the proprioceptive weighting ratio (dRPW) is calculated to deduce therefrom the weight assigned by the CNS to the various proprioceptive inputs during the postural task.