Details

Autor(en) / Beteiligte

• Castellani, John W
• Young, Andrew J
• Degroot, David W
• Stulz, Dean A
• Cadarette, Bruce S
• Rhind, Shawn G
• Zamecnik, Jiri
• Shek, Pang N
• Sawka, Michael N

Titel

Thermoregulation during cold exposure after several days of exhaustive exercise

Ist Teil von

• Journal of applied physiology (1985), 2001-03, Vol.90 (3), p.939-946

Ort / Verlag

Bethesda, MD: Am Physiological Soc

Erscheinungsjahr

2001

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 1  Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007; and 2  Biomedical Technology Section, Defence and Civil Institute of Environmental Medicine, Toronto, Ontario, Canada M3M 3B9 This study examined the hypothesis that several days of exhaustive exercise would impair thermoregulatory effector responses to cold exposure, leading to an accentuated core temperature reduction compared with exposure of the same individual to cold in a rested condition. Thirteen men (10 experimental and 3 control) performed a cold-wet walk (CW) for up to 6 h (6 rest-work cycles, each 1   h in duration) in 5°C air on three occasions. One cycle of CW consisted of 10 min of standing in the rain (5.4 cm/h) followed by 45 min of walking (1.34 m/s, 5.4 m/s wind). Clothing was water saturated at the start of each walking period (0.75 clo vs. 1.1   clo when dry). The initial CW trial ( day 0 ) was performed (afternoon) with subjects rested before initiation of exercise-cold exposure. During the next 7 days, exhaustive exercise (aerobic, anaerobic, resistive) was performed for 4 h each morning. Two subsequent CW trials were performed on the afternoon of days 3  and 7 , ~2.5 h after cessation of fatiguing exercise. For controls, no exhaustive exercise was performed on any day. Thermoregulatory responses and body temperature during CW were not different on days 0, 3 , and 7  in the controls. In the experimental group, mean skin temperature was higher ( P  < 0.05) during CW on days 3  and 7  than on day 0 . Rectal temperature was lower ( P  < 0.05) and the change in rectal temperature was greater ( P  < 0.05) during the 6th h of CW on day 3 . Metabolic heat production during CW was similar among trials. Warmer skin temperatures during CW after days 3  and 7  indicate that vasoconstrictor responses to cold, but not shivering responses, are impaired after multiple days of severe physical exertion. These findings suggest that susceptibility to hypothermia is increased by exertional fatigue. fatigue; hypothermia; norepinephrine; shivering; vasoconstriction