Elderly's ability to manage the cold may be due in part to some aging processes o...( women) individuals participated. The vo...)

women) individuals participated. The volunteers were nonsmokers and took no medications that could alter their cardiovascular or thermoregulatory responses to cool temperatures. Participants underwent a standardized medical screening and physical exam, and researchers measured or calculated the ten physical characteristics noted above for each subject. Researchers then inserted a thermometer sealed in a pediatric feeding tube into each participant who then entered a controlled environmental chamber and was positioned in a reclining position. The room's baseline temperature remained stable for 20 minutes and was decreased thereafter at a rate of 0.2C per minute for 20 minutes and 0.05C per minute after that to approximate mild cold exposure. The participants were removed when visible, sustained shivering was observed by the investigators or reported by the volunteer.

Multiple-regression analyses were performed to determine the predictors of body temperature and tissue insulation, and standardized regression coefficients were analyzed to determine the relative influence of each of the ten candidate variables.

Findings and Conclusions

The researchers observed the following:

• in young subjects, percent body fat and T3 hormone explained most of the variance in body temperature response to cold. Among older persons, the percent of body fat, the skeletal muscle mass, or both was responsible for similar amounts of variability in the response to cold;

• the sum of skin folds was responsible for 67 percent (P<0.01) of the body temperature variance in young subjects versus two percent of the body temperature variation in older subjects;

• unexplained variance of body temperature to cold was considerably less in younger participants (14-42 percent) than in older participants (59-72 percent).

These results suggest that the well known changes in body composition char
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Contact: Donna Krupa
dkrupa@the-aps.org
301-634-7209
American Physiological Society
18-Jan-2007

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