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Improving Pedal Symmetry: assessment and therapy

David A. Brown, PT, PhD; Charles G Burgar, MD; Christine Dairaghi, BS; Sandy Dunn Gabrielli; Steven A. Kautz, PhD

Objective - Approximately one half of a million persons in the United States will suffer a stroke this year. Many of them will be left with weakness and poor control on one side of the body, and will require rehabilitation to regain the ability to walk. The objective of this project is to develop better techniques for performing this rehabilitation. Specifically, we are interested in developing practical treatments that employ dynamic exercise in conjunction with feedback about patient performance.

to receive figure click here Figure 1. The screen shows the left leg is not producing as much force as the right.

Approach - Our approach is to train hemiplegic patients to use their affected legs more effectively while pedaling a stationary bicycle ergometer. We choose to use pedaling because it is a dynamic, bilateral task which has many similarities to walking but is safer and can be performed when the patient is not yet ambulatory. In addition, since pedaling is a simple, constrained motion, its biomechanics are much easier to measure and to analyze than those of gait, providing a cost-effective way to quantitatively assess the patient's original deficit and response to therapy.

In the most recent part of our study, five patients who had strokes or traumatic brain injuries resulting in varying degrees of lower-limb impairment underwent thirty training sessions over a 10 week period. During the training sessions, the patients pedaled the ergometer against a moderate resistance. They tried to pedal symmetrically, that is, to push down and pull up as forcefully with their affected leg as with their nonaffected leg. They were provided with feedback about the relative forces produced by their legs to help them accomplish this. All the patients showed improved symmetry by the end of the training sessions.

To see whether improved pedaling symmetry carried over to improved gait, the patient's gait was assessed at several points throughout the training session. Each assessment involved measuring vertical ground reaction forces during the stance phase in each leg, step length, and cadence. Four patients showed increased vertical ground reaction forces in their affected legs, indicative of improved weight-bearing capability. Three subjects showed increased step length, indicative of a more normal gait. The one subject who showed no improvement was only mildly impaired and had essentially normal gait to begin with.

Conclusion - Our findings show that our training regimen to improve pedaling symmetry does not degrade the patient's ability to walk and may in fact have a significant beneficial effect. Our current plans call for a more thorough evaluation of the treatment using a larger, more homogeneous patient population and a control population.

Republished from the 1994 Rehabilitation R&D Center Progress Report.

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