Seifert, J. G., & Seabright, J. (1998). Heat acclimation rates in prepubescent and adult females. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 1267.

Girls (N = 6; 9-11 years) and women (N = 6; 21-35 years) cycled at 70% of maximum heart rate for 46 minutes per day for nine days at 33 degrees Celsius. Blood samples were obtained one month before the activity and the day after completing the exercise.

Percent change in plasma volume increased significantly by day 9 in the women (5.27%) but not in the girls (-1.6%). Plasma osmality also increased in the women but not in the girls. Plasma protein and heart rate decreased in the women but was maintained in the girls. Sweat rate was similar between the two age groups before exposure to the heat but was greater in women by day 9. Exercising core temperature did not change in women but decreased significantly in girls over the last four days.

Implication. Women adapt fully within nine days of exercise in the heat but girls showed little adaptation over the same period.

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