In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 292, No. 1 ( 2007-01), p. R143-R149
Abstract:
Exercise increases mean body temperature (T̄ body ) and cytokine concentrations in plasma. Cytokines facilitate PG production via cyclooxygenase (COX) enzymes, and PGE 2 can mediate fever. Therefore, we used a COX-2 inhibitor to test the hypothesis that PG-mediated pyrogenicity may contribute to the raised T̄ body in exercising humans. In a double-blind, cross-over design, 10 males [age: 23 yr (SD 5), V̇o 2 max : 53 ml·kg −1 ·min −1 (SD 5)] consumed rofecoxib (50 mg/day; NSAID) or placebo (PLAC) for 6 days, 2 wk apart. Exercising thermoregulation was measured on day 6 during 45-min running (∼75% V̇o 2 max ) followed by 45-min cycling and 60-min seated recovery (28°C, 50% relative humidity). Plasma cytokine (TNF-α, IL-10) concentrations were measured at rest and 30-min recovery. T̄ body was similar at rest in PLAC (35.59°C) and NSAID (35.53°C) and increased similarly during running, but became 0.33°C (SD 0.26) lower in NSAID during cycling (37.39°C vs. 37.07°C; P = 0.03), and remained lower throughout recovery. Sweating was initiated at T̄ body of ∼35.6°C in both conditions but ceased at higher T̄ body in PLAC than NSAID during recovery [36.66°C (SD 0.36) vs. 36.39°C (SD 0.27); P = 0.03]. Cardiac frequency averaged 6·min −1 higher in PLAC ( P 〈 0.01), whereas exercising metabolic rate was similar (505 vs. 507 W·m −2 ; P = 0.56). A modest increase in both cytokines across exercise was similar between conditions. COX-2 specific NSAID lowered exercising heat and cardiovascular strain and the sweating (offset) threshold, independently of heat production, indicating that PGE-mediated inflammatory processes may contribute to exercising heat strain during endurance exercise in humans.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.00926.2005
Language:
English
Publisher:
American Physiological Society
Publication Date:
2007
detail.hit.zdb_id:
603839-6
detail.hit.zdb_id:
1477297-8
SSG:
12
Permalink