Mechanism for glycogenolysis in nonexercising human muscle during and after exercise

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Abstract
Arterial-deep venous differences for glucose and lactate across the nonexercising forearm were determined in healthy subjects during 3 h of leg exercise at 50% of maximum oxygen uptake and during 20-min recovery. At 160 min of exercise 0.5 mg propranolol was infused into the brachial artery. The results were compared with a control group that did not receive propranolol during exercise. Exercise stimulated to increased forearm lactate release which was higher than that which could be accounted for by the simultaneous blood glucose uptake. After propranolol forearm lactate production decreased during and after exercise while the controls still showed increasing lactate release. In contrast to the control values the lactate production by the blocked forearm could be accounted for by the glucose uptake. It is concluded that the stimulating effect of prolonged exercise on nonexercising muscle that persists during recovery is characterized by increased lactate release derived from beta-adrenergically stimulated glycogenolysis.