PCP Aging and Temperature Regulation

Question 1

What is the hypothesis for the point and the counterpoint?

Answer 1

Point: aging does impair temp regulation in humans

Counter Point: aging does not impair temp regulation in humans

Question 2

What evidence is there for point (aging does impair temperature regulation in humans)?

Answer 2

1. Frank et al. younger and 8 older male subjects in terms of sympathetic neuronal and vasomotor responses, sensory thermal perception, and total body oxygen consumption to identify thermoregulatory differences during core cooling. In support of the point hypothesis, the older participants demonstrated a decreased Tc threshold and maximum response for vasoconstriction, decreased total body oxygen consumption, and decreased subjective sensory thermal perception
2. Wagner et al. compared the thermoregulatory performance of young and middle-aged men on the first day of heat acclimation while performing treadmill walking at at a moderate pace in dry heat. The results demonstrated that the younger participants maintained lower Tre, Tsk, and HR, while their mean sweat rate was higher when compared to the older subjects during the acute-heat stress exposure. In support of the point hypothesis, it was concluded that the middle-aged men exhibited more limited secretory and sensitivity capacity in their sweating mechanism compared to the younger men, contributing to their inferior temperature regulation
3. One study looked at older adults, age were 64, which four were men and five were women. Results were compared to that of younger adults, mean age of 23, from a previous study by the same authors. All subjects wore a water-perfused suit through which 50°C water was perfused to cause a 1°C increase in their oral temperature (Tor) from baseline. Tor was clamped for five minutes by lowering the water temperature perfusing the suit. SkBF in the arm was significantly lower in the older group for the entire duration of the heating and in the lower back when Tor was 0.2-0.9°C above baseline.

Question 3

What evidence is there for counterpoint (aging does not impair temperature regulation in humans)?

Answer 3

1. Smolander et al. tested the performance in both warm-humid and hot-dry environments of unacclimated young and unacclimated older men. The results of the experiment indicated that both age groups displayed similar final Tre, Tsk, HR, Msw, rating of perceived exertion (RPE), and thermal sensation (TS). To counter the point hypothesis, it was concluded that older age is not necessarily associated with a reduced ability to exercise in a hot environment. Rather, it was thought that the ability to exercise in heat was an effect of other factors, such as habitual physical activity, health status, and VO2max
2. Lee et al. compared thermal and metabolic responses between a young and old age participant groups during a 3-hr immersion in water judged cool enough to elicit maximal cutaneous vasoconstriction. To counter the point hypothesis, it was concluded that the reduction in peripheral blood flow produced by maximal vasoconstriction in the cold was similar for both old and young participants
3. For studies that have found evidence that aging does impair temperature regulation, the older groups often have significantly higher baseline body fat % than the younger groups. Higher body fat would reduce their “skin-to-ambient thermal gradient” and increase their thermal insulation. This may result in them having higher skin temps and cause them to vasoconstrict at a lower core temp (“warm hands, cold heart”). Thus body fat %, rather than aging, may explain this result