Article

The mechanical effect of hamstrings and quadriceps contractions on hip and knee
joint motion was investigated using a dynamic model of the musculoskeletal
system. The model consisted of 13 anatomically linked segments.
The geometry of
bones, joints, and muscle attachments was derived from magnetic resonance imaging
of a healthy adult. The knee joint was represented by a crossing bars linkage to
simulate cruciate ligament function, and muscles were represented by spring
actuators. The effects of hamstring and quadriceps contractions, in various
combinations, were tested on different configurations of hip and knee joint
position in the absence of gravity. In the standing posture, with the foot free
to move and the pelvis fixed in space, the effect of semimembranosus (SM)
contraction was hip and knee flexion. If the foot was fixed to the ground, SM
contraction produced hip extension and knee flexion.
The addition of quadriceps
contraction reduced or abolished the knee flexion and enhanced hip extension. In all other simulations, SM alone produced knee flexion and hip extension and the
combination of SM with vastus (VA) and rectus femoris (RF) contractions resulted
in knee extension and enhanced hip extension. Our findings suggest that
co-contraction of quadriceps and hamstrings may be a strategy to increase the hip
extension function of the hamstrings.
CI - Copyright 2009 Elsevier B.V. All rights reserved.

Langue : ANGLAIS