REPETITIVE PRE-COOLING ONLY IMPROVES THE PRE-COOLING RESPONSE
Kocjan, N., Schatti, O., Bogerd, C. P., & Rossi, R. M. (2009). The effect of repetitive cooling on pre-cooling efficiency and exercise performance: A pilot study. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.
This study investigated: i) if repetitive cooling increases the efficiency of pre-cooling and, ii) how such a response affects various thermo-physiological parameters during exercise in hot and humid ambient conditions. Physically fit men (N = 4) reported to the laboratory for 10 consecutive days. Each time, Ss were exposed to one hour of cooling with an ice vest while sitting at an ambient temperature of ~20.2°C. On the first and the tenth day, this was followed by 25 minutes of cycling exercise at 60% VO2peak in ~30.2°C and a relative humidity of ~71.4%. On the first and tenth days, during cooling and exercise, body core temperature and skin temperatures on eight body locations, were registered every 10 seconds. In addition, during the first and the last five minutes of cooling, forearm skin blood flow was measured. Rating of thermal perception was noted every 15 minutes.
Skin blood flow increased ~80% by the tenth day, indicating a decrease in vasoconstrictor response. Cooling decreased skin temperatures on both occasions to a similar extent. However, on the tenth day, the time to reach that value was halved. Core temperature before cooling was slightly higher on the tenth day but by the end of cooling was similar for both days. On average, thermal perception improved from -2.3 on the first day to -1.3 on the tenth day. During subsequent exercise there were no apparent differences between the first and the tenth cooling days in any of the variables investigated.
Implication. Ten consecutive days of cooling with an ice vest improves the efficiency of pre-cooling, ascribed mainly to a reduction in the vasoconstrictor response. Repetitive cooling does not affect any of the investigated thermo-physiological parameters during subsequent exercise performance in warm and humid ambient environments.
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