Increased air velocity during exercise in the heat leads to equal reductions in hydration shifts and interleukin-6 with age

Eur J Appl Physiol. 2014 Oct;114(10):2081-92. doi: 10.1007/s00421-014-2931-9. Epub 2014 Jun 19.

Abstract

Purpose: The effectiveness of increased air velocity in reducing hydration shifts and physiological strain during work in the heat was examined in young and older males.

Methods: Ten young (mean ± SE, 24 ± 1 years) and 10 older (59 ± 1 years) males, matched for height, mass, and body surface area, cycled 4 × 15-min at moderate-to-heavy heat production (400 W), with 15-min rest separations between exercise bouts (final recovery 30 min), while wearing work clothing in humid heat (35 °C, 60 % relative humidity) under low (~0.5 m s(-1)) and high (~3.0 m s(-1)) air velocity. Rectal temperature (T re) and heart rate were measured continuously, whereas hydration indices and interleukin (IL)-6 were measured at rest (PRE) and following the final recovery (POST).

Results: Young and older males experienced similar thermal and cardiovascular strain within the low (T re end-exercise: young = 38.28 ± 0.11, older = 38.31 ± 0.08 °C) and high (T re end-exercise: young = 37.94 ± 0.08, older = 37.87 ± 0.08 °C) air velocity conditions, with a reduced increase in both groups in high compared to low. Percent changes in plasma volume were similarly greater during the low (young = -10.9 ± 1.2, older = -10.8 ± 0.9 %) compared to high (young = -5.7 ± 0.6, older = -6.9 ± 0.7 %) condition for both groups. Despite elevated IL-6 at PRE in the older males, the IL-6 absolute change was similar between young (low = +4.10 ± 0.95, high = +0.99 ± 0.32 pg mL(-1)) and older (low = +3.58 ± 0.83, high = +1.24 ± 0.28 pg mL(-1)) males yet greater during the low compared to high condition.

Conclusions: Increased air velocity was effective in reducing the increase in hydration shifts and physiological strain (i.e. IL-6, thermal and cardiovascular strain) equally in young and older males.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Air Movements*
  • Body Temperature
  • Case-Control Studies
  • Exercise / physiology*
  • Fluid Shifts*
  • Heart Rate
  • Hot Temperature*
  • Humans
  • Humidity
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Plasma Volume

Substances

  • Interleukin-6