Aging and Heat Stress: From Rest to Exercise

The current thesis examined local and whole-body heat loss responses during heat stress at rest, exercise and/or pharmacological stimuli as a function of increasing age. The first study examined the effects of age on whole-body heat loss and heat storage during passive exposure to conditions representative of the upper temperature extremes in Canada. The results demonstrate that the cumulative change in body heat content after 2 h of rest was significantly greater in older adults in a hot-dry (older: 212±25; young: 131±27 kJ, P=0.018) and hot-humid (older: 426±37; young: 317±45 kJ, P=0.037) condition. The second study evaluated the maximal capacity of whole-body evaporative heat loss as a function of age and aerobic fitness. The findings demonstrate that whole-body evaporative heat loss was significantly lower in middle-aged untrained (Ex2: 426±34; Ex3:497±17 W) and older (Ex2: 424±38; Ex3: 485±44 W) compared to young (Ex2: 472±42; Ex3: 558±51 W) and middle-aged trained (Ex2: 474±21; Ex3: 552±23 W) males at the end of the last two exercise bouts (P