The responses of the catecholamines and beta-endorphin to brief maximal exercise in man.

The responses to brief maximal exercise of 10 male subjects have been studied. During 30 s of exercise on a non-motorized treadmill, the mean power output (mean +/- SD) was 424.8 +/- 41.9 W, peak power 653.3 +/- 103.0 W and the distance covered was 167.3 +/- 9.7 m. In response to the exercise blood lactate concentrations increased from 0.60 +/- 0.26 to 13.46 +/- 1.71 mmol.l-1 (p less than 0.001) and blood glucose concentrations from 4.25 +/- 0.45 to 5.59 +/- 0.67 mmol.l-1 (p less than 0.001). The severe nature of the exercise is indicated by the fall in blood pH from 7.38 +/- 0.02 to 7.16 +/- 0.07 (p less than 0.001) and the estimated decrease in plasma volume of 11.5 +/- 3.4% (p less than 0.001). The plasma catecholamine concentrations increased from 2.2 +/- 0.6 to 13.4 +/- 6.4 nmol.l-1 (p less than 0.001) and 0.2 +/- 0.2 to 1.4 +/- 0.6 nmol.l-1 (p less than 0.001) for noradrenaline (NA) and adrenaline (AD) respectively. The plasma concentration of the opioid beta-endorphin increased in response to the exercise from less than 5.0 to 10.2 +/- 3.9 p mol.l-1. The post-exercise AD concentrations correlated with those for lactate as well as with changes in pH and the decrease in plasma volume. Post-exercise beta-endorphin levels correlated with the peak speed attained during the sprint and the subjects peak power to weight ratio. These results suggest that the increases in plasma adrenaline are related to those factors that reflect the stress of the exercise and the contribution of anaerobic metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)