Revisiting the mechanics and energetics of walking in individuals with chronic hemiparesis following stroke: from individual limbs to lower limb joints

Finally someone objectively looking at stroke deficits. What is your therapist going to do with this knowledge to reduce your fatigue?

Revisiting the mechanics and energetics of walking in individuals with chronic hemiparesis following stroke: from individual limbs to lower limb joints

Abstract
Background
Previous reports of the mechanics and energetics of post-stroke hemiparetic walking have
either not combined estimates of mechanical and metabolic energy or computed external
mechanical work based on the limited combined limbs method. Here we present a
comparison of the mechanics and energetics of hemiparetic and unimpaired walking at a
matched speed.
Methods
Mechanical work done on the body centre of mass (COM) was computed by the individual
limbs method and work done at individual leg joints was computed with an inverse dynamics
analysis. Both estimates were converted to average powers and related to simultaneous

estimates of net metabolic power, determined via indirect calorimetry. Efficiency of positive
work was calculated as the ratio of average positive mechanical power ˉ to net metabolic
power.
Results
Total ˉ was 20% greater for the hemiparetic group (H) than for the unimpaired control
group (C) (0.49 vs. 0.41 W · kg−1). The greater ˉ was partly attributed to the paretic limb of
hemiparetic walkers not providing appropriately timed push-off ˉ in the step-to-step
transition. This led to compensatory non-paretic limb hip and knee ˉ which resulted in
greater total mechanical work. Efficiency of positive work was not different between H and
C.
Conclusions
Increased work, not decreased efficiency, explains the greater metabolic cost of hemiparetic
walking post-stroke. Our results highlighted the need to target improving paretic ankle pushoff
via therapy or assistive technology in order to reduce the metabolic cost of hemiparetic
walking.