Effect of swimming in thermal water on skeletal muscle, liver and heart glycogen

: Skeletal muscle, liver and heart glycogen variations, induced by swimming in thermal water (at 35 degrees C) as a model of physical exercise for clinical use, were studied. Muscle and liver glycogen moderately decreases after a 30-min period of swimming and comes near to depletion after 60 min. Heart glycogen decreases only slightly after 60 min. Blood glucose and plasma insulin decrease only after 60 min of swimming. A 30-min swim in thermal water, cooled to 25 degrees C, depletes muscle and liver glycogen and slightly decreases heart glycogen. Under these conditions, plasma insulin decreases and hypoglycemia occurs. The results seem to indicate some advantages of swimming in hot thermal water in order to prevent glycogen store depletion as the physiological prerequisite for a physical exercise of clinical interest to obtain therapeutical benefits, avoiding premature fatigue and exhaustion.