Sympathetic neural regulation in endurance-trained humans: fitness vs. fatness

J Appl Physiol (1985). 2005 Feb;98(2):498-502. doi: 10.1152/japplphysiol.01020.2004. Epub 2004 Oct 15.

Abstract

We tested the hypothesis that muscle sympathetic nerve activity (MSNA) would be higher in endurance-trained (ET) compared with sedentary (Sed) men with similar levels of total body and abdominal adiposity. We further hypothesized that sympathetic baroreflex gain would be augmented in ET compared with Sed men independent of the level of adiposity. To address this, we measured MSNA (via microneurography), sympathetic and vagal baroreflex responses (the modified Oxford technique), body composition (dual-energy X-ray absorptiometry), and waist circumference (Gulick tape) in Sed (n = 22) and ET men (n = 8). The ET men were also compared with a subgroup of Sed men (n = 6) with similar levels of total body and abdominal adiposity. Basal MSNA was greater in the ET compared with Sed men with similar levels of total body and abdominal adiposity (28 +/- 2.0 vs. 21 +/- 2.0 bursts/min; P < 0.05) but similar to the larger group of Sed men (n = 22) with higher total body and abdominal adiposity (vs. 26 +/- 3 bursts/min; P > 0.05). In contrast to our hypothesis, sympathetic baroreflex gain was lower in the ET compared with Sed men (-6.4 +/- 0.8 vs. -8.4 +/- 0.4 arbitrary integrative units x beat(-1) x mmHg(-1); P < 0.05) regardless of the level of adiposity. Taken together, the results of the present study suggest that MSNA is higher in ET compared with Sed men with similar levels of total body and abdominal adiposity. In addition, sympathetic baroreflex gain is lower in ET compared with Sed men. That sympathetic baroreflex gain was lower in ET compared with Sed men regardless of the level of adiposity suggests an influence of the ET state per se.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adipose Tissue / physiology*
  • Adult
  • Baroreflex / physiology
  • Body Constitution / physiology*
  • Homeostasis / physiology
  • Humans
  • Male
  • Muscle, Skeletal / innervation*
  • Muscle, Skeletal / physiology*
  • Physical Education and Training / methods
  • Physical Endurance / physiology*
  • Physical Fitness / physiology*
  • Statistics as Topic
  • Sympathetic Nervous System / physiology*