Evidence for β-adrenergic modulation of sweating during incremental exercise in habitually trained males

J Appl Physiol (1985). 2017 Jul 1;123(1):182-189. doi: 10.1152/japplphysiol.00220.2017. Epub 2017 May 4.

Abstract

The aim of the present study was to determine the β-adrenergic contribution to sweating during incremental exercise in habitually trained males. Nine habitually trained and 11 untrained males performed incremental cycling until exhaustion (20 W/min). Bilateral forearm sweat rates (ventilated capsule) were measured at two skin sites that were transdermally administered via iontophoresis with either 1% propranolol (Propranolol, a nonselective β-adrenergic receptor antagonist) or saline (Control). The sweat rate was evaluated as a function of both relative (percentage of maximum workload) and absolute exercise intensities. The sweat rate at the Propranolol site was lower than the control during exercise at 80 (0.57 ± 0.21 and 0.45 ± 0.19 mg·cm-2·min-1 for Control and Propranolol, respectively) and 90% (0.74 ± 0.22 and 0.65 ± 0.17 mg·cm-2·min-1, respectively) of maximum workload in trained males (all P < 0.05). By contrast, no between-site differences in sweat rates were observed in untrained counterparts (all P > 0.05). At the same absolute intensity, higher sweat rates on the control site were observed in trained males relative to the untrained during exercise at 160 (0.23 ± 0.20 and 0.04 ± 0.05 mg·cm-2·min-1 for trained and untrained, respectively) and 180 W (0.40 ± 0.20 and 0.13 ± 0.13 mg·cm-2·min-1, respectively) (all P < 0.05), whereas this between-group difference was not observed at the Propranolol site (all P > 0.05). We show that the β-adrenergic mechanism does modulate sweating during exercise at a submaximal high relative intensity in habitually trained males. The β-adrenergic mechanism may in part contribute to the greater sweat production in habitually trained males than in untrained counterparts during exercise.NEW & NOTEWORTHY We demonstrated for the first time that the β-adrenergic mechanism does modulate sweating (i.e., β-adrenergic sweating) during exercise using a localized β-adrenoceptor blockade in humans in vivo. β-Adrenergic sweating was evident in habitually trained individuals during exercise at a submaximal high relative intensity (80-90% maximal work). This observation advances our understanding of human thermoregulation during exercise and of the mechanism that underlies sweat gland adaptation to habitual exercise training.

Keywords: adrenoceptor; cAMP; cholinoceptor; eccrine sweat glands; thermoregulation.

MeSH terms

  • Adrenergic beta-Antagonists / pharmacology*
  • Athletes
  • Bicycling / physiology
  • Exercise / physiology*
  • Forearm / physiology
  • Humans
  • Male
  • Propranolol / pharmacology
  • Receptors, Adrenergic, beta / physiology*
  • Skin / drug effects
  • Skin Physiological Phenomena / drug effects
  • Sweat / drug effects
  • Sweat / physiology
  • Sweating / drug effects
  • Sweating / physiology*
  • Young Adult

Substances

  • Adrenergic beta-Antagonists
  • Receptors, Adrenergic, beta
  • Propranolol