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The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment.
Acta Physiol Scand. 2005 Mar; 183(3):241-55.AP

Abstract

AIM

The purposes of this study were to determine (i) the effects of different facing air velocities on body temperature and heat storage during exercise in hot environmental conditions and (ii) the effects of ingesting fluids at two different rates on thermoregulation during exercise in hot conditions with higher air velocities.

METHODS

On five occasions nine subjects cycled for 2 h at 33.0 +/- 0.4 degrees C with a relative humidity of 59 +/- 3%. Air velocity was maintained at 0.2 km h(-1) (0 WS), 9.9 +/- 0.3 km h(-1) (10 WS), 33.3 +/-2.2 km h(-1) (100 WS) and 50.1 +/- 3.2 km h(-1) (150 WS) while subjects replaced 58.8 +/- 6.8% of sweat losses. In the fifth condition, air velocity was maintained at 33.7 +/- 2.2 km h(-1) and subjects replaced 80.0 +/- 6.8% of sweat losses (100.80 WS).

RESULTS

Heat storage, body temperature and rating of perceived exertion were higher in 0 and 10 WS compared with all other conditions. There were no differences in any measured variable between 100 and 150 WS, or between 100 and 100.80 WS. Thus, the evaporative capacity of the environment is increased with higher air velocities, reducing heat storage and body temperature. At higher air velocities, a higher rate of fluid ingestion did not influence heat storage, body temperature or sweat rate.

CONCLUSION

The finding of previous laboratory studies showing a beneficial effect of high rates of fluid ingestion on thermoregulation during exercise in hot, humid, windstill conditions cannot be extrapolated to out-of-doors exercise in which facing air velocities are seldom lower than the athlete's rate of forward progression.

Authors+Show Affiliations

Department of Human Biology, UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Sports Science Institute of South Africa, Newlands 7725, South Africa.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15743384

Citation

Saunders, A G., et al. "The Effects of Different Air Velocities On Heat Storage and Body Temperature in Humans Cycling in a Hot, Humid Environment." Acta Physiologica Scandinavica, vol. 183, no. 3, 2005, pp. 241-55.
Saunders AG, Dugas JP, Tucker R, et al. The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. Acta Physiol Scand. 2005;183(3):241-55.
Saunders, A. G., Dugas, J. P., Tucker, R., Lambert, M. I., & Noakes, T. D. (2005). The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. Acta Physiologica Scandinavica, 183(3), 241-55.
Saunders AG, et al. The Effects of Different Air Velocities On Heat Storage and Body Temperature in Humans Cycling in a Hot, Humid Environment. Acta Physiol Scand. 2005;183(3):241-55. PubMed PMID: 15743384.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. AU - Saunders,A G, AU - Dugas,J P, AU - Tucker,R, AU - Lambert,M I, AU - Noakes,T D, PY - 2005/3/4/pubmed PY - 2005/5/4/medline PY - 2005/3/4/entrez SP - 241 EP - 55 JF - Acta physiologica Scandinavica JO - Acta Physiol Scand VL - 183 IS - 3 N2 - AIM: The purposes of this study were to determine (i) the effects of different facing air velocities on body temperature and heat storage during exercise in hot environmental conditions and (ii) the effects of ingesting fluids at two different rates on thermoregulation during exercise in hot conditions with higher air velocities. METHODS: On five occasions nine subjects cycled for 2 h at 33.0 +/- 0.4 degrees C with a relative humidity of 59 +/- 3%. Air velocity was maintained at 0.2 km h(-1) (0 WS), 9.9 +/- 0.3 km h(-1) (10 WS), 33.3 +/-2.2 km h(-1) (100 WS) and 50.1 +/- 3.2 km h(-1) (150 WS) while subjects replaced 58.8 +/- 6.8% of sweat losses. In the fifth condition, air velocity was maintained at 33.7 +/- 2.2 km h(-1) and subjects replaced 80.0 +/- 6.8% of sweat losses (100.80 WS). RESULTS: Heat storage, body temperature and rating of perceived exertion were higher in 0 and 10 WS compared with all other conditions. There were no differences in any measured variable between 100 and 150 WS, or between 100 and 100.80 WS. Thus, the evaporative capacity of the environment is increased with higher air velocities, reducing heat storage and body temperature. At higher air velocities, a higher rate of fluid ingestion did not influence heat storage, body temperature or sweat rate. CONCLUSION: The finding of previous laboratory studies showing a beneficial effect of high rates of fluid ingestion on thermoregulation during exercise in hot, humid, windstill conditions cannot be extrapolated to out-of-doors exercise in which facing air velocities are seldom lower than the athlete's rate of forward progression. SN - 0001-6772 UR - https://www.unboundmedicine.com/medline/citation/15743384/The_effects_of_different_air_velocities_on_heat_storage_and_body_temperature_in_humans_cycling_in_a_hot_humid_environment_ L2 - https://doi.org/10.1111/j.1365-201X.2004.01400.x DB - PRIME DP - Unbound Medicine ER -