Cortisol is a catabolic hormone which induces the breakdown
of cellular proteins. Cortisol helps maintain plasma glucose
levels during a fast, by stimulating gluconeogenesis / lipolysis
and inhibiting lipid synthesis. Glucocorticoids decrease muscle
protein synthesis and increase muscle protein degradation so
amino acids will be available for glucose production.
Cortisol also increases whole body lipolysis, in part, by
enhancing GH and catecholamine stimulated lipolysis, yet chronic
hypercortisolemia results in increased fat mass (Samra 1998).
Cortisol increases as intense exercise is prolonged (Di Pasquale,
1992c). In men, significant elevations in cortisol seem to reduce
endogenous testosterone by acting directly upon the testis to
impair the biosynthesis of testosterone (Di Pasquale, 1992c).
Submaximal exercise at lower intensities (i.e. 63% maximum oxygen
consumption) stimulates lower cortisol response than higher intensities
(i.e. 86% maximum oxygen consumption) (Farrell, Garthwaite, &
Gustafson, 1983; Naveri, 1985).
Cortisol increases whole body lipolysis
Dehydroepiandrosterone is steroid prohormone produced from
cholesterol by the adrenal glands, the gonads, adipose tissue,
brain and in the skin (by an autocrine mechanism). DHEA is the
precursor of androstenedione which can undergo further conversion
to produce testosterone and estrogens.