Thermoregulation during prolonged exercise in heat: Alterations with β-adrenergic blockade

B. J. Freund, Michael Joseph Joyner, S. M. Jilka, J. Kalis, J. M. Nittolo, J. A. Taylor, H. Peters, G. Feese, J. H. Wilmore

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Thermoregulation and cardiovascular drift were studied under conditions of prolonged exercise in a warm environment (dry bulb temperature 31.7 ± 0.3°C, rh 44.7 ± 4.7%) during β-adrenergic blockade. Fourteen subjects performed 90-min rides on a cycle ergometer at a work rate equivalent to 40% of their control maximal O2 uptake under each of three treatments provided in a randomized double-blind manner: atenolol (100 mg/day), propranolol (160 mg/day), and a placebo. Exercise during the propranolol trial resulted in significantly higher forearm vascular resistance values and significantly lower forearm blood flows (FBF) compared with the placebo trial. However, the significantly lower FBF during propranolol did not significantly alter the rectal temperature (T(re)) response to prolonged exercise. In addition, both β-blockers produced lower FBF for any given T(re), suggesting that β-adrenergic blockade affects FBF through nonthermal factors. The slight differences in T(re), despite the large differences in FBF between the various treatments, are apparently the result of an enhanced sweat loss and a lower mean skin temperature during exercise with β-blockade. The uncoupling of FBF and sweat loss provides evidence of independent regulation. The reduction in FBF at any given T(re) was concomitant to lower blood pressure values during β-blockade and suggests that baroreflexes provide significant input to the control of skin blood flow when both pressure and temperature maintenance are simultaneously challenged.

Original languageEnglish (US)
Pages (from-to)930-936
Number of pages7
JournalJournal of Applied Physiology
Volume63
Issue number3
StatePublished - 1987
Externally publishedYes

Fingerprint

Body Temperature Regulation
Forearm
Adrenergic Agents
Hot Temperature
Temperature
Propranolol
Sweat
Placebos
Atenolol
Skin Temperature
Baroreflex
Vascular Resistance
Maintenance
Blood Pressure
Pressure
Skin
Therapeutics

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Freund, B. J., Joyner, M. J., Jilka, S. M., Kalis, J., Nittolo, J. M., Taylor, J. A., ... Wilmore, J. H. (1987). Thermoregulation during prolonged exercise in heat: Alterations with β-adrenergic blockade. Journal of Applied Physiology, 63(3), 930-936.

Thermoregulation during prolonged exercise in heat : Alterations with β-adrenergic blockade. / Freund, B. J.; Joyner, Michael Joseph; Jilka, S. M.; Kalis, J.; Nittolo, J. M.; Taylor, J. A.; Peters, H.; Feese, G.; Wilmore, J. H.

In: Journal of Applied Physiology, Vol. 63, No. 3, 1987, p. 930-936.

Research output: Contribution to journalArticle

Freund, BJ, Joyner, MJ, Jilka, SM, Kalis, J, Nittolo, JM, Taylor, JA, Peters, H, Feese, G & Wilmore, JH 1987, 'Thermoregulation during prolonged exercise in heat: Alterations with β-adrenergic blockade', Journal of Applied Physiology, vol. 63, no. 3, pp. 930-936.
Freund, B. J. ; Joyner, Michael Joseph ; Jilka, S. M. ; Kalis, J. ; Nittolo, J. M. ; Taylor, J. A. ; Peters, H. ; Feese, G. ; Wilmore, J. H. / Thermoregulation during prolonged exercise in heat : Alterations with β-adrenergic blockade. In: Journal of Applied Physiology. 1987 ; Vol. 63, No. 3. pp. 930-936.
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