Why does endurance performance decline in hot, humid conditions despite adequate hydration and electrolyte intake, when compared to performance in cooler environments?

💡 Explanation

The cardiac output becomes insufficient because in hot, humid environments, the thermoregulatory mechanism of vasodilation increases blood flow to the skin to dissipate heat. This increased demand, coupled with the need to perfuse muscles, means cardiac output cannot meet both needs, therefore endurance declines, rather than being limited by glycogen, respiration, or vasoconstriction.

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