Distribution of blood flow in the muscles of conscious animals during exercise

This study reviews the recent research on the distribution of blood flow within and among skeletal muscles in conscious animals during locomotory exercise. A brief description of the technique that has been used in these studies, the radiolabeled microsphere method, is presented, including a short discussion of the assumptions that must be met in using the methodology. Distinct patterns of flow distribution occur in the muscles during exercise that are related to the fiber-type composition of the muscles or muscle parts (and, presumably, the patterns of fiber recruitment) and the intensity of the exercise. The mechanisms that regulate the differential elevations in blood flow within and among the muscles at the initiation of exercise have not been elucidated. However, studies on the conscious animal model indicate that the control cannot be totally explained by local metabolic factors, sympathetic influences or mechanical effects.