Article

This study examined lower extremity biomechanics during the initiation of stair
descent from an upright, static posture. Seventeen healthy subjects (aged
23+/-2.4 years) descended a five-step, steel-reinforced, wooden laboratory
staircase (34 degrees decline). Ten trials of stair descent were separated into
two blocks of five trials. Beginning from an upright posture, subjects descended
the staircase at their preferred velocity (0.53+/-0.082 m/s) and continued the
length of the laboratory walkway ( approximately 4 m).
Joint mechanics were
contrasted between gait cycles. Relative to the initiation cycle at the top of
the staircase, the dissipative knee extensor (K3) and hip flexor (H2) moments and
powers were independent of progression velocity and approximated steady-state
(i.e., constant) values after the first cycle of the trail limb (Step 5 to Step
3). In contrast, a salient relationship was observed between progression velocity
and ankle joint mechanics at initial-contact. The plantiflexor moment, power and
work at initial-contact (A1) increased with centre of mass velocity. Our results
demonstrate that while the knee extensor moment is the primary dissipater of
mechanical energy in stair descent, the ankle plantiflexors are the primary
dissipaters associated with increased progression velocity. In addition, the
results show that steady-state stair descent may not be attained during the first
gait cycle of the trail limb. These data shed light on locomotive strategies used
in stair descent and can be applied in biomechanical models of human stair gait.
Researchers and practitioners should take into consideration the influence of
gait cycle and progression velocity when evaluating lower extremity function in stair descent.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS