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1 School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
2 Toxicology Program and Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
* To whom correspondence should be addressed. E-mail: gkenny{at}uottawa.ca.
The purpose of the study was to evaluate the possible differences in the postexercise cutaneous vasodilatory response between men and women. Fourteen subjects (7 women) of similar age, body composition and fitness status remained seated resting for 15 min or cycled for 15 min at 70% of peak oxygen consumption followed by 15 min of seated recovery. Subjects then donned a liquid conditioned suit. Mean skin temperature was clamped at ~34°C for 15 min. Mean skin temperature was then increased at a rate of 4.3 ± 0.8°C.hr-1 while local skin temperature was clamped at 34°C. Skin blood flow was measured continuously at two forearm skin sites, one with (UT) and without (BT) (treated with bretylium tosylate) intact
-adrenergic vasoconstrictor activity. The exercise threshold for cutaneous vasodilation for women (37.51±0.08°C and 37.58±0.04°C for UT and BT respectively) was greater than that measured in men (37.33±0.06°C and 37.35±0.06°C for UT and BT respectively) (p<0.05). Core temperatures were similar to baseline prior to the start of whole-body warming for all conditions. Postexercise heart rate (HR) for the men (77±4 beats/min) and women (87±6 beats/min) were elevated above baseline (61±3 beats/min and 68±4 beats/min for men and women respectively) whereas mean arterial pressure (MAP) for the men (84±3 mmHg) and women (79±3 mmHg) was reduced from baseline (93±3 mmHg and 93±4 mmHg for men and women respectively) (p<0.05). A greater increase in HR and a greater decrease in the MAP postexercise was noted in women (p<0.05). No differences in core temperature, HR and MAP were measured in the no-exercise trial. The postexercise threshold for cutaneous vasodilation measured at the UT and BT sites for men (37.15±0.03°C and 37.16±0.04°C respectively) and women (37.36±0.05°C and 37.42±0.03°C respectively) were elevated above no-exercise (36.94±0.07°C and 36.97±0.05°C for men and 36.99±0.09°C and 37.03±0.11°C for women for the UT and BT sites respectively)(p<0.05). A difference in the magnitude of the thresholds was measured between women and men (p<0.05). We conclude that women have a greater postexercise onset threshold for cutaneous vasodilation than do men and that the primary mechanism influencing the difference between men and women in postexercise skin blood flow is likely the result of an altered active vasodilatory response and not an increase in adrenergic vasoconstrictor tone.
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