Int J Sports Med 2006; 27(12): 943-950
DOI: 10.1055/s-2006-923863
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

Exercise Tolerance in a Hot and Humid Climate in Heat-Acclimatized Girls and Women

A. M. Rivera-Brown1 , 2 , T. W. Rowland3 , F. A. Ramírez-Marrero4 , G. Santacana2 , A. Vann5
  • 1Center for Sports Health and Exercise Sciences, Department of Physical Medicine, Rehabilitation and Sports Medicine, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
  • 2Department of Physiology and Biophysics, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
  • 3Department of Pediatrics, Baystate Medical Center, Springfield, MA, USA
  • 4Department of Physical Education and Recreation, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
  • 5Department of Health, Physical Education, Recreation and Sport Science, St. Cloud State University, St. Cloud, MN, USA
Further Information

Publication History

Accepted after revision: November 30, 2005

Publication Date:
30 May 2006 (online)

Abstract

This study compared physiological responses associated with exercise tolerance in girls (G) and women (W) of similar fitness and heat acclimatization level during exercise in a hot and humid outdoor environment (33.4 °C and 55.1 % RH; WBGT = 29.9 ± 0.2 °C). Nine pre-menarcheal G (age = 11.3 yr) and nine W (age = 26.8 yr), matched for aerobic capacity and heat acclimatization level, performed a cycling session at 60 % V·O2max until fatigue. A sports drink was provided periodically to prevent dehydration. Tolerance time was not different between the groups (G = 56.9 ± 6.3, W = 76.5 ± 9.9 min, p > 0.05). During exercise, sweat rate (G = 9.1 ± 1.1, W = 12.0 ± 1.1 ml · m-2 · min-1), the increase in rectal temperature [Tre] (G = 0.9 ± 0.1, W = 1.1 ± 0.1 °C), and heat storage (G = 10.6 ± 5.3, W = 20.5 ± 4.5 W · m-2) did not differ between the groups. At fatigue, Tre (G = 38.2 ± 0.1, W = 38.4 ± 0.1 °C), heart rate (G = 167.3 ± 7.3, W = 171 ± 3.3 beats · min-1), stroke index (G = 48.3 ± 1.5, W = 52.4 ± 1.8 ml · m-2), and forearm skin blood flow (G = 9.5 ± 1.3, W = 11.7 ± 1.5 ml · 100 ml- 1 · min-1) did not differ between the groups. Similar to women, the main reasons reported by girls to stop exercising in the heat were localized leg fatigue and gluteus muscle discomfort. We conclude that heat-acclimatized girls exhibit an adequate cardiovascular and thermoregulatory adjustment while exercising in a hot and humid outdoor environment when hypohydration is prevented.

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Ph.D. Anita M. Rivera-Brown

Center for Sports Health and Exercise Sciences

P.O. Box 2004

Salinas, Puerto Rico 00751

Phone: + 7878242669

Fax: + 787 8 24 26 69

Email: aniriver@coqui.net

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