Are circulating cytokine responses to exercise in the heat augmented in older men?

Appl Physiol Nutr Metab. 2014 Feb;39(2):117-23. doi: 10.1139/apnm-2013-0223. Epub 2013 Jul 24.


Age-related chronic low-grade inflammation may render older individuals more susceptible to heat illnesses. The purpose of this study was to examine the influence of intermittent work in the heat on the circulating cytokine responses of older workers. Fourteen young (aged 25.6 ± 0.7 years) and older (aged 57.7 ± 1.5 years) males, matched for body surface area, cycled for 4 × 15 min (separated by 15-min rest) at moderate to heavy intensity (400 W heat production) in warm/dry (35 °C, 20% relative humidity (RH)) and warm/humid (35 °C, 60% RH) conditions. Rectal (Tre) and mean skin (MTsk) temperatures and heart rate were measured continuously, ratings of perceived exertion and thermal sensation recorded at the end of each exercise bout, and blood samples at baseline (PRE) and following the final 60-min recovery (POST) were analyzed for interleukin (IL)-6, tumor necrosis factor (TNF)-α, and percent changes in blood (BV) and plasma (PV) volumes. No differences were observed between the age groups for Tre, MTsk, heart rate, perceptual strain, or percentage of changes in BV, PV, or ΔTNF-α. Under both conditions, the older males had elevated IL-6 and TNF-α (PRE, POST) compared with the young males. ΔIL-6 tended to be greater in the warm/humid condition (+2.53 ± 0.49 and +1.52 ± 0.41 pg·mL(-1)) compared with the warm/dry condition (+1.02 ± 0.13 and +0.68 ± 0.18 pg·mL(-1)) for older but not young males, respectively. Young and older males experienced similar thermal, cardiovascular, and perceptual strain within the warm/dry and warm/humid conditions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Body Temperature*
  • Exercise / physiology*
  • Hot Temperature
  • Humans
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Tumor Necrosis Factor-alpha / blood*


  • IL6 protein, human
  • Interleukin-6
  • Tumor Necrosis Factor-alpha