Article

Forward propulsion is a central task of walking that depends on the generation of
appropriate anterior-posterior ground reaction forces (AP GRFs). The AP impulse
(i.e., time integral of the AP GRF) generated by the paretic leg relative to the
non-paretic leg is a quantitative measure of the paretic leg's contribution to
forward propulsion and is variable across hemiparetic subjects. The purpose of
this study was to investigate the underlying mechanisms of propulsion generation
in hemiparetic walking by identifying the biomechanical predictors of AP
impulses. Three-dimensional kinematics and GRFs were recorded from 51 hemiparetic
and 21 age-matched control subjects walking at similar speeds on an instrumented
treadmill. Hierarchical regression models were generated for each leg to predict
the AP impulse from independent biomechanical variables. Leg extension was a
significant predictor and positively related to the propulsive impulse in the
paretic, non-paretic and control legs. Secondarily, the hip flexor moment impulse
was negatively related to the propulsive impulse. Also, the relationship of
paretic and non-paretic ankle moments with the propulsive impulse depended on the
paretic step ratio, suggesting the plantar flexor contribution to the propulsive
impulse depends on leg angle. These results suggest that increasing paretic leg
extension will increase propulsion. Increasing paretic plantar flexor output and
decreasing paretic hip flexor output could also increase paretic leg propulsion.
While increased pre-swing hip flexor output has been suggested to compensate for
decreased plantar flexor output, such output may further impair propulsion by the
paretic leg if it occurs too soon in the gait cycle.
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Langue : ANGLAIS