SECONDARY COMPLICATIONS OF SCI
Mark S. Nash, Ph.D. • Patrick L. Jacobs, Ph.D.

People with SCI are at a heightened risk of developing early cardiovascular disease. A reduction of physical activity either imposed on or adopted by people with SCI is one factor that contributes to its early onset. Dr. Nash, principal investigator at the Miami Project since its inception, has conducted many studies on the effects exercise has on reducing the risk of cardiovascular disease after SCI. Recognized internationally for his work, he was invited to write several manuscripts to summarize the current body of knowledge for this topic. In a chapter on cardiovascular fitness, he emphasizes the importance of identifying effective and readily available exercise activities that help reduce cardiovascular disease risks as people age with their disability. He also describes how circulatory dysfunction after SCI may affect their capacity to exercise.

Depending on the level of injury, various types of circulatory dysfunction are seen after SCI. In persons with paraplegia, the decreased volume and speed of blood flow returning to the heart from the paralyzed extremities is a dysfunction called hypokinetic circulation. Another Miami Project researcher, Dr. Jacobs has undertaken several studies to examine how SCI changes blood flow. In a study with 20 paraplegic men, he measured how much blood the heart pumped with each beat (stroke volume), how much blood pumped in one minute (cardiac output) and heart rate. When compared with non-disabled sedentary volunteers, men with SCI had lower cardiac output at rest and during exercise. This observation suggests a decreased ability for blood in the lower extremities to return to the heart (venous return). Methods to increase venous return may improve the ability of persons with SCI to perform physical activities, and thus experience better benefit from upper extremity exercise. Work done in the Miami Project Human Performance Laboratories continues to evaluate interventions designed to reduce secondary complications after SCI, thus optimizing quality of life for people with SCI.