Thermal stress (43.3°C) significantly reduced cardiac output, central blood volume, and stroke volume during moderate to severe exercise compared to 25.6°C in normal, unacclimatized men.
Absolute Event Rate: 18.6% vs 19.8%
p-value: p=<0.001
Observations on heat-acclimatized men by As- mussen (1) and Williams and colleagues (2) showed no increase in cardiac output above the normal response during exercise in a hot, humid environment. Indeed, Asmussen found decre- ments in cardiac output below normal responses if moderate work in the heat (32C, 80% rela- tive humidity) was prolonged from 30 to 60 minutes. No systematic study has been reported of cardiac output during exercise at high ambient temperature in men unacclimatized to heat.
Rowell et al. (Tue,) conducted a other in Healthy volunteers (n=6). Thermal stress during exercise vs. 25.6°C (78°F) was evaluated on Cardiac output at 15% grade exercise (L/min) (p=<0.001). Thermal stress (43.3°C) significantly reduced cardiac output, central blood volume, and stroke volume during moderate to severe exercise compared to 25.6°C in normal, unacclimatized men.