title: Increased air velocity during exercise in the heat leads to equal reductions in hydration shifts and interleukin-6 with age.
abstract: OBJECTIVE
  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.
authors.affiliation: Flight Research Laboratory, National Research Council Canada, Ottawa, K1A 0R6, Canada.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Wright-Beatty
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Hardcastle
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulay
authors.forename: Joanie
authors.initials: J
authors.lastname: Larose
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D000367:Age Factors; D000392:Air Movements; D001831:Body Temperature; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D018495:Fluid Shifts; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010953:Plasma Volume
chemical_list: D015850:Interleukin-6