Abstract des Autors

This study investigated the effect ofpartial body cooling (cold towels and showers) on the responses to heat stress during exercise. After a short acclimatization period, six subjects rode a Monark bicycle ergometer for 59 min. alternating 5 min. work with 1 min. rest in a hot environment (105 F (40.6 C) dry bulb, 83 F (28.3 C) wet bulb). Heart rate, rectal temperature, and sweat loss were measured and plotted for three experimental conditions - C-control; E1-cold towel application (1 C) to abdomen and head during the rest periods and E2-same as E1 except for a preexercise 10-min. cold shower at 14.8 C (58.6 F). Heart rates, rectal temperatures, and sweat losses were less under the two experimental conditions than under the control condition. The subjects responded most favorably to the heat stress under condition E2. Heart rate, rectal temperature, and sweat loss results were combined to compute the modified Craig Index of Physiological Strain, I8 = terminal heart rate (beats/min)/100 + delta Trectal (degrees C/hr) + delta Wtnude (kg/hr). Mean values were 4.55, 4.06, and 3.36 for C, E1, and E2, respectively. Analysis of variance showed all mean differences to be statistically significant beyond the .05 level. It was concluded that partial body cooling by heat stress by enhancing the heat dissipating mechanisms of the body. Cold towels applied to the abdomen and head periodically during the exercise period apparently aid in cooling the blood and help in conduction of heat from the body surface. Verf.-Referat