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

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. Ten young (mean +/- A SE, 24 +/- A 1 years) and 10 older (59 +/- A 1 years) males, matched for height, mass, and body surface area, cycled 4 x 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 A degrees C, 60 % relative humidity) under low (similar to 0.5 m s(-1)) and high (similar to 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). Young and older males experienced similar thermal and cardiovascular strain within the low (T (re) end-exercise: young = 38.28 +/- A 0.11, older = 38.31 +/- A 0.08 A degrees C) and high (T (re) end-exercise: young = 37.94 +/- A 0.08, older = 37.87 +/- A 0.08 A degrees 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 +/- A 1.2, older = -10.8 +/- A 0.9 %) compared to high (young = -5.7 +/- A 0.6, older = -6.9 +/- A 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 +/- A 0.95, high = +0.99 +/- A 0.32 pg mL(-1)) and older (low = +3.58 +/- A 0.83, high = +1.24 +/- A 0.28 pg mL(-1)) males yet greater during the low compared to high condition. 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.