The influence of passive stretch on muscle oxygen saturation.

Previous studies have suggested that chronic stretch might be able to produce skeletal muscle hypertrophy. However, stretching might also restrict blood flow, which could in turn influence any stretch-training program. This study evaluated the influence of muscle stretch on muscle oxygen saturation using near infrared spectroscopy (NIRS). A 16 channel NIRS probes were placed on the medial gastrocnemius, quadriceps, and hamstring muscles of young healthy adults. Oxygen saturation during maximal tolerated stretch was measured and normalized with cuff-induced ischemia and reperfusion. Oxygen saturation decreased in the gastrocnemius and quadriceps in a position dependent fashion, but did not change in the hamstring muscles. Passive stretching may also have a significant hypoxic component in some muscles but not others.