Journal of Applied Physiology, Vol 71, Issue 5 1807-1812, Copyright © 1991 by American Physiological Society

ARTICLES

Effect of low blood glucose on plasma CRF, ACTH, and cortisol during prolonged physical exercise

I. Tabata, F. Ogita, M. Miyachi and H. Shibayama
Department of Physiology and Biomechanics, National Institute of Fitness and Sports, Kagoshima Prefecture, Japan.

The effects of low blood glucose concentration during low-intensity prolonged physical exercise on the hypothalamus-pituitary-adrenocortical axis were investigated in healthy young men. In experiment 1, six subjects who had fasted for 14 h performed bicycle exercise at 50% of their maximal O2 uptake until exhaustion. At the end of the exercise, adrenocorticotropic hormone (ACTH) and cortisol increased significantly. However, this hormonal response was totally abolished when the same subjects exercised at the same intensity while blood glucose concentrations were maintained at the preexercise level. In experiment 2, in addition to ACTH and cortisol, the possible changes in plasma concentration of corticotropin-releasing factor (CRF) were investigated during exercise of the same intensity performed by six subjects. As suggested by a previous study (Tabata et al. Clin. Physiol. Oxf. 4: 299-307, 1984), when the blood glucose concentrations decreased to less than 3.3 mM, plasma concentrations of CRF, ACTH, and cortisol showed a significant increase. At exhaustion, further increases were observed in plasma CRF, ACTH, and cortisol concentrations. These results demonstrate that decreases in blood glucose concentration trigger the pituitary-adrenocortical axis to enhance secretion of ACTH and cortisol during low-intensity prolonged exercise in humans. The data also might suggest that this activation is due to increased concentration of CRF, which was shown to increase when blood glucose concentration decreased to a critical level of 3.3 mM.

This article has been cited by other articles:

				W J Kraemer, M S Fragala, G Watson, J S Volek, M R Rubin, D N French, C M Maresh, J L Vingren, D L Hatfield, B A Spiering, et al. Hormonal responses to a 160-km race across frozen Alaska Br. J. Sports Med., February 1, 2008; 42(2): 116 - 120. [Abstract] [Full Text] [PDF]

				W. J. Inder, J. Hellemans, M. P. Swanney, T. C. R. Prickett, and R. A. Donald Prolonged exercise increases peripheral plasma ACTH, CRH, and AVP in male athletes J Appl Physiol, September 1, 1998; 85(3): 835 - 841. [Abstract] [Full Text] [PDF]

				A. B. Loucks, M. Verdun, and E. M. Heath Low energy availability, not stress of exercise, alters LH pulsatility in exercising women J Appl Physiol, January 1, 1998; 84(1): 37 - 46. [Abstract] [Full Text] [PDF]

				J. W. Castellani, C. M. Maresh, L. E. Armstrong, R. W. Kenefick, D. Riebe, M. Echegaray, D. Casa, and V. D. Castracane Intravenous vs. oral rehydration: effects on subsequent exercise-heat stress J Appl Physiol, March 1, 1997; 82(3): 799 - 806. [Abstract] [Full Text] [PDF]