Plasma catecholamine response to exercise and cold adaptation.

Abstract : Male rats were administered light, moderate, and heavy exercise programs for 3 weeks. Following the exercise programs, the nonexercised control and the three exercised groups were administered a cold-tolerance test at -20C for 3 hr. At the end of 3 hr the mean colonic temperature of the nonexercised group was 31.9C while those of the exercised animals were 35.7-36.5C. All groups exposed to -20C showed significant increases in plasma norepinephrine, epinephrine, and cortico;terone when compared to a second nonexercised control group which was sacrificed at 25C (P < 0.01). Within the cold-exposed groups, the exercised animals exhibited plasma catecholamine and corticosteroid levels that were significantly lower than the nonexercised group (P < 0.01). The findings indicate that physical training enhances cold tolerance in rats. (Modified author abstract)