Individual variations in nitric oxide synthase-dependent sweating in young and older males during exercise in the heat: role of aerobic power

Physiol Rep. 2017 Mar;5(6):e13208. doi: 10.14814/phy2.13208.


We evaluated the association between aerobic power (defined by peak oxygen consumption; VO2peak) and the contribution of nitric oxide synthase (NOS) to the sweating response in young and older individuals during exercise in the heat. Data from 44 young (24 ± 1 years) and 48 older (61 ± 2 years) males with mean VO2peak of 47.8 ± 2.4 (range, 28.0-62.3) and 39.1 ± 2.3 (range, 26.4-55.7) mLO2 kg-1 min-1, respectively, were compiled from our prior studies. Participants performed two 15- to 30-min bouts of exercise at a fixed rate of metabolic heat production of 400 or 500 W, each separated by 15-20 min recovery in the heat (35°C, relative humidity of 20%). Forearm sweat rate (ventilated capsule technique) was measured at two skin sites that were continuously and simultaneously administered with lactated Ringers solution (Control) or 10 mmol/L NG -nitro-L-arginine methyl ester (L-NAME, nonselective NOS inhibitor) via intradermal microdialysis. Sweat rate during the final 5 min of each exercise bout was lower with L-NAME compared to the Control in both groups (all P < 0.05). The magnitude of the attenuation in sweat rate induced by L-NAME compared to the Control was not correlated with VO2peak (all P 0.46) while this attenuation was negatively correlated with the sweat rate at the Control in both groups and in both exercise bouts (all P < 0.01, R ≤ -0.43). These results suggest that NOS-dependent sweating is not associated with aerobic power per se, while it becomes evident in individuals who produce larger sweat rates during exercise irrespective of age.

Keywords: Aerobic power; aging; eccrine sweat glands; exercise training; nitric oxide.

MeSH terms

  • Adult
  • Enzyme Inhibitors / pharmacology
  • Exercise / physiology*
  • Forearm / blood supply
  • Hot Temperature
  • Humans
  • Individuality*
  • Male
  • Middle Aged
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide Synthase / antagonists & inhibitors*
  • Oxygen Consumption / drug effects
  • Oxygen Consumption / physiology*
  • Regional Blood Flow / drug effects
  • Sweating / drug effects
  • Sweating / physiology*
  • Vasodilation / drug effects
  • Young Adult


  • Enzyme Inhibitors
  • Nitric Oxide Synthase
  • NG-Nitroarginine Methyl Ester