Abstract
Some peptides are released with stress. We therefore examined effects of different
exercise stress at low and moderate altitudes and after heat stress on beta-endorphin
and endothelin in the human circulation. We also assessed longitudinally the effects
of chronic exertion on beta-endorphin and the relationship to melatonin secretion
in well-trained athletes. All peptides and melatonin increased after exercise, but
the magnitude of this increase was age-dependent. Chronic exertion is associated with
a decrease in exercise induced opioid release and in such individuals melatonin secretion
is not beta-endorphin related. Long term high altitude exposure is associated with
high-beta-endorphin levels at rest. Atrial natriuretic factor and vasopressin is also
released with exercise at moderate altitude. Endothelin, a powerful vasoconstrictor,
is increased independent of type of exercise, duration and moderate hypoxia.
Key words
Beta-endorphin - endothelin - exercise - melatonin
