Ideally, rehabilitation following a stroke that leads to functional deficit will result in a rapid return to normal function. In the real world, however, a rapid improvement in function is rarely achieved. Between 80% and 90% of stroke survivors have a motor deficit, with impairments in walking being the most common motor deficits. 1 Most stroke survivors have a diminished fitness reserve that is stable and resistant to routine rehabilitative interventions. Recent research has begun to assess the value of exercise and other modalities of training during this period of stability to improve function long after cessation of other therapeutic interventions. This article will review this research and provide insight into those issues in post-stroke rehabilitation that remain to be addressed and may affect heart and brain physiology.
STROKE REDUCES AEROBIC CAPACITY
At all ages, the fitness level of stroke survivors, as measured by maximum oxygen consumption, is reduced by approximately 50% below that of an age-matched normal population. In a study comparing peak oxygen consumption during treadmill walking between stroke survivors and age-matched sedentary controls, we found that the stroke participants had an approximately 50% lower level of peak fitness relative to the control subjects. 2 During treadmill walking at self-selected speeds, the stroke volunteers used 75% of their functional capacity, compared with 27% for the age-matched healthy controls. Furthermore, compared with the controls, the stroke subjects demonstrated a poorer economy of gait that required greater oxygen consumption to sustain their self-selected walking speeds.
CLINICAL TRIALS OF POST-STROKE EXERCISE REHABILITATION
In light of the efficacy of treadmill exercise in cardiac rehabilitation, we are evaluating whether treadmill exercise can similarly improve fitness, endurance, and walking velocity in stroke survivors. We have completed 6 months of treadmill training in two separate cohorts that show highly consistent results in terms of improved walking abilities in hemiparetic stroke subjects. 3,4 A third cohort is in progress to confirm these findings and examine the effects of intensity on the functional benefits 5 and mechanisms 6 underlying the effects of treadmill training.
Treadmill exercise results in functional benefits and improved glucose metabolism
The first cohort was a before-and-after comparison of stable stroke survivors who underwent a three-times-weekly treadmill exercise program for 6 months. 3 Peak exercise capacity testing (VO 2peak) revealed functional benefits with minimal cardiac and injury risk compared with baseline, demonstrating the feasibility and safety of treadmill exercise therapy in stroke-impaired adults.