Blood hormone and metabolite levels during graded cycle ergometer exercise

To study the effect of the intensity of physical exercise on plasma hormone and metabolite levels, a group of 11 well-conditioned males participated in cycle ergometer exercise. The subjects pedalled at three different work loads, corresponding to 63% of VO2max (duration 10 min), 86% of VO2max (duration 10 min) and maximal work load (tolerated 5-7 min) The increases in blood adrenaline, noradrenaline, growth hormone, cyclic AMP, glycerol and lactate concentrations were remarkably similar and exponentially related to the work load. The concentrations of blood glucose, cortisol and glucagon increased only at maximal work load. Many of these changes in blood metabolite and hormone concentrations seem to be related to the increased sympathetic activity during graded exercise.