14 DAYS IS TOO SHORT FOR HEAT ACCLIMATIZATION
Voltaire, B., Galy, O., Coste, O., Racinais, S., Calllis, A., Blonc, S., Hertogh, C., & Hue, O. (2002). Effect of fourteen days of acclimatization on athletic performance in tropical climate. Canadian Journal of Applied Physiology, 27, 551-562.
Triathletes (N = 9) performed four outdoor indirect multistage running tests in thermoneutral (14 degrees Celsius in Canada) and tropical conditions (~33 degrees Celsius in Martinique) over 14 days. Tropical tests were performed on days 2, 8, and 14 after arrival.
The athletes showed a marked response to the heat upon arrival in the tropics. Sweat rate was significantly greater in all hot trials than in the cool. Sweat rate increased as adaptation to the heat occurred. Tympanic temperature was significantly higher initially and gradually declined in the heat but never to the level recorded in the cool. Body mass loss after exercise was greatest at the end of the heat period, increasing as time in the heat grew. Heart rate and heart rate at rest were significantly higher on day 2 in the heat than at the other three times. On day 14, heart rate was significantly lower than on the other three test days. Performance was worse at all times in the heat than in the cool.
Implication. Hot humid conditions produce physiological disruptions and performance decrement in trained cool-adapted athletes. Fourteen days of acclimatization is insufficient to produce stable acclimatization.
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