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European Journal of Applied Physiology

, Volume 112, Issue 6, pp 2313–2321 | Cite as

Influence of relative humidity on prolonged exercise capacity in a warm environment

  • Ronald J. MaughanEmail author
  • Hidenori Otani
  • Phillip Watson
Original Article

Abstract

This study examined the influence of relative humidity on endurance exercise performance in a warm environment. Eight male volunteers performed four cycle exercise trials at 70% maximum oxygen uptake until volitional exhaustion in an environmental chamber maintained at 30.2 ± 0.2°C. Volunteers were tested under four relative humidity (rh) conditions: 24, 40, 60 and 80%. Core and weighted mean skin temperature, heart rate, skin blood flow, and cutaneous vascular conductance were recorded at rest and at regular intervals during exercise. Mean ± SD time to exhaustion was 68 ± 19, 60 ± 17, 54 ± 17, and 46 ± 14 min at 24, 40, 60, and 80% rh, respectively (P < 0.001); exercise time was significantly less at 60% (P = 0.013) and 80% (P = 0.005) rh than recorded at 24% rh. There were no differences in core temperature (P = 0.480) and heart rate (P = 0.097) between trials. Core temperature at exhaustion was 39.0 ± 0.3°C at 24, 40, and 60% rh and 39.1 ± 0.3°C at 80% rh (P = 0.159). Mean skin temperature at the point of exhaustion was higher at 80% rh than at 24% rh (P < 0.001). Total sweat loss was similar between trials (P = 0.345), but sweating rate was higher at 60 and 80% rh than at 24% rh (P < 0.001). The results suggest that exercise capacity at moderate intensity in a warm environment is progressively impaired as the relative humidity increases.

Keywords

Fatigue Thermoregulation Hyperthermia Core temperature Skin temperature 

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Ronald J. Maughan
    • 1
    Email author
  • Hidenori Otani
    • 1
  • Phillip Watson
    • 1
  1. 1.School of Sport, Exercise and Health SciencesLoughborough UniversityLeicestershireUK

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