Effects of heat exposure and 3% dehydration achieved via hot water immersion on repeated cycle sprint performance

J Strength Cond Res. 2011 Mar;25(3):778-86. doi: 10.1519/JSC.0b013e3181c1f79d.

Abstract

This study examined effects of heat exposure with and without dehydration on repeated anaerobic cycling. Males (n = 10) completed 3 trials: control (CT), water-bath heat exposure (∼39°C) to 3% dehydration (with fluid replacement) (HE), and similar heat exposure to 3% dehydration (DEHY). Hematocrit increased significantly from pre to postheat immersion in both HE and DEHY. Participants performed 6 × 15s cycle sprints (30s active recovery). Mean Power (MP) was significantly lower vs. CT (596 ± 66 W) for DEHY (569 ± 72 W), and the difference approached significance for HE (582 ± 76 W, p = 0.07). Peak Power (PP) was significantly lower vs. CT (900 ± 117 W) for HE (870 ± 128 W) and approached significance for DEHY (857 ± 145 W, p = 0.07). Postsprint ratings of perceived exertion was higher during DEHY (6.4 ± 2.0) and HE (6.3 ± 1.6) than CT (5.7 ± 2.1). Combined heat and dehydration impaired MP and PP (decrements greatest in later bouts) with HE performance intermediate to CT and DEHY.

MeSH terms

  • Adult
  • Athletic Performance / physiology*
  • Bicycling / physiology*
  • Drinking*
  • Heart Rate / physiology
  • Heat-Shock Response*
  • Hematocrit
  • Hot Temperature*
  • Humans
  • Immersion*
  • Male
  • Young Adult