Responses of Lean and Obese Boys to Repeated Summer Exercise in the Heat Bouts

• Autores: Kelly A. Dougherty, Mosuk Chow, W. Larry Kenney
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 41, Nº. 2, 2009, págs. 279-289
• Idioma: inglés
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• Resumen

  • Purpose: To determine the degree of natural acclimatization and artificially induced acclimation-related changes during repeated exercise in the heat bouts in seven lean and seven obese 9- to 12-yr-old boys during summer months.

    Methods: Beginning at random times during the summer, subjects underwent a 70-min exercise (30% V[spacing dot above]O2max) in the heat exposure (38[degrees]C, 50% relative humidity) on six separate days.

    Results: On day 1, obese children were less naturally acclimatized as indicated by significantly higher baseline core temperatures (Tc) (obese = 37.62 +/- 0.06 vs lean = 37.41 +/- 0.06; P < 0.004). By day 6 versus day 1, significant reductions in baseline Tc were evident in both groups (obese = 37.41 +/- 0.04 vs lean = 37.18 +/- 0.04; both P < 0.05). Baseline Tc in obese subjects by day 6 was similar to that of lean subjects on day 1. Daily reductions in exercise Tc were evident in both groups (final exercising Tc day 1 vs day 6: obese = 38.15 +/- 0.05 vs 37.89 +/- 0.05; lean = 38.17 +/- 0.09 vs 37.72 +/- 0.06[degrees]C; both P < 0.001), occurring at a significantly slower rate in obese subjects (final exercise Tc day 6 - day 1: obese vs lean = -0.26 +/- 0.04 vs -0.45 +/- 0.08[degrees]C; P < 0.05). Significant reductions in exercising heart rate (HR) occurred in the lean but not the obese subjects by day 6 (final exercising HR day 1 vs day 6: obese = 132 +/- 3 vs 131 +/- 3, P > 0.05; lean = 138 +/- 3 vs 127 +/- 3 bpm; P < 0.001).

    Conclusions: During summer months, obese children are less naturally heat-acclimatized and subsequently acclimate at a slower rate.