Metabolic effects of physical training.

Effects of physical training on factors associated with diabetes mellitus and its increased risk for cardiovascular disease are reviewed. Plasma insulin levels are decreased by training particularly in obesity and glucose tolerance seems to be improved. Training leads also in general to diminished body fat, but this is not obligatory for the plasma insulin decrease. There are no changes in concentrations of amino acids growth hormone or catecholamines, which can explain the insulin decrease. Cortisol is decreased the days after an acute exercise as well as after training in parallel with the plasma insulin decrease. The cortisol decrease may lead to changes in insulin receptor density in tissues leading to increased insulin sensitivity. The insulin decrease seems to be due to both a decreased production (to about 2/3) and an increased clearance (to about 1/3). Physical training leads to a decrease in plasma triglycerides and to a decrease in blood pressure. All these effects of physical training seem to be beneficial in the treatment of diabetes mellitus.