Cardiovascular reactions to cold exposures differ with age and gender

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Abstract
This study was conducted since virtually no information was available concerning age- and gender-related differences in cardiovascular adjustments to cold exposure. Men and women between the ages of 20 and 30 and 51 and 72 yr, wearing swim suits, rested for 2 h in 28, 20, 15, and 10 degrees C ambient temperatures (Ta), with 40% relative humidity. Cardiac output (Qc) and stroke volumes (Qs) were higher in younger than older subjects regardless of Ta. Cardiac output was not influenced by gender, but all cold exposures resulted in increased Qs and decreased heart rate in men but not women. Regardless of age or gender, Qc increased about 10% only during exposure to 10 degrees C. Cold exposure resulted in minimal increases in the mean systolic and diastolic pressures (Pa) of the younger subjects. The Pa of older subjects were higher than in the young during 28 degrees C exposures and increased during all cold exposures. Total peripheral resistance and forearm blood flows were higher in older than young subjects exposed to cold. Total peripheral resistance, systolic and diastolic Pa, and finger and forearm blood flows were not affected by gender, but hand plus forearm blood flows were higher in men than women exposed to 28 degrees C. Although Qc appeared adequate to meet increased oxygen demands of shivering in the older subjects, rising Pa may become limiting in extended exposures. A similar response in hypertensive or angina-prone individuals may result in some untoward responses.