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Effect of Strength Training on Upper-Limb Function in Post-Stroke Patients

Investigators: Peter S. Lum, PhD and Carolynn Patten, PhD PT

Project Staff: Charles G. Burgar, MD, Kevin C. McGill, PhD, and John E. Drace, MD

Project Category: Stroke - 2000

World War II veterans now constitute the largest proportion of persons eligible for health care in VA facilities. Most of these veterans are over 65 years of age and at significantly increased risk for stroke. In anticipation of the medical and rehabilitative needs of our rapidly aging veteran population, research efforts targeting effective rehabilitation interventions for motor disability resulting from stroke are needed.

Individuals who have suffered a stroke are left with many significant motor impairments: weakness (abnormally decreased joint torque levels during maximal effort exercise), slowness of movement, impaired dexterity/control of muscular force, hypertonia (abnormally increased resistance to passive movement), diminished joint range of motion, and dyscoordination of intersegmental movements. However, there is growing evidence that the dominant impairment is weakness. Paradoxically, strength training (high-exertion, resistance exercise constrained to a single joint) has traditionally been regarded as inappropriate for stroke patients primarily due to the belief that excessive effort exacerbates hypertonia. Despite the fact that this tenet is increasingly being challenged in the recent literature, the potential therapeutic benefits of strength training following stroke have not been fully investigated.

In this proposal, we will use a controlled, randomized, double blind clinical trial to study the effects of shoulder and elbow strength training in subjects in the subacute phase of recovery following stroke. We define the subacute phase as having completed all out-patient therapy programs, but still less than 6 months post-CVA. We will compare an experimental intervention of standard functional rehabilitation combined with elbow and shoulder strength training against a control intervention of standard functional rehabilitation. We hypothesize that the subjects who receive strength training in addition to standard functional rehabilitation will demonstrate greater gains in elbow and shoulder strength (defined as the joint torque output during maximal effort exercise) and greater improvements in functional performance than the control group, without increased hypertonia. We will study the neuromuscular mechanisms underlying the improvements in strength and control of movement that result from these interventions.

Should the results demonstrate that resistance exercise does in fact exacerbate hypertonia, then this study would provide scientific evidence for avoiding high-exertion activity in this population. On the other hand, if, as we anticipate, the results demonstrate that resistance exercise can improve functional performance without exacerbating hypertonia, then this study would elucidate some of the physiological mechanisms involved with adaptive change in persons affected with post-stroke hemiparesis, and it would contribute to a scientific basis for prescribing resistance exercise for this population. This in turn can be expected to lead to more effective and efficient rehabilitation treatments.

Funding Source: VA RR&D Merit Review