Propulsive Forces Applied to the Body’s Center of Mass Affect Metabolic Energetics Post-Stroke

Publication date: Available online 2 November 2018

Source: Archives of Physical Medicine and Rehabilitation

Author(s): Kelly Penke, Korre Scott, Yunna Sinskey, Michael Lewek

Abstract

Objective

To investigate the effect of timing and magnitude of horizontally directed propulsive forces to the center of mass (COM) on the metabolic cost of walking for individuals following stroke.

Design

Repeated measures, within-subjects design

Setting

Research laboratory

Participants

Nine individuals with chronic hemiparesis post-stroke and seven unimpaired similarly aged controls

Intervention

Individuals walked on a treadmill in two separate studies. First, we compared the metabolic cost of walking with an anterior force applied to the COM that 1) coincided with paretic propulsion or 2) was applied throughout the gait cycle. Next, we compared the metabolic cost of walking with anterior (assistive) or posterior (resistive) forces applied during paretic propulsion.

Main Outcome Measure

metabolic cost of walking

Results

The cost of walking was significantly greater in the Stroke group. Anterior (propulsive) assistance reduced the cost of walking differently based on group. The Stroke group exhibited a 12% reduction in cost of walking when assistance was provided only during paretic propulsion, but not when assistance was provided throughout the gait cycle. In contrast, the Control group demonstrated reduced cost of walking during both anterior assistance conditions. In addition, we observed that resistance during paretic propulsion (simulated hemiparesis for Control group) significantly increased the cost of walking.

Conclusions

Systematically manipulating propulsive forces at the body's COM had a profound influence on metabolic cost. The timing of propulsive forces to the COM are important and need to coincide with paretic terminal stance. Additional internally or externally generated propulsive forces applied to the body's COM after stroke may produce a lower metabolic cost of walking.

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