How does hyperthermia influence exercise performance and cognitive function?

• A. Improves endurance and cognitive function.
• B. No change in performance.
• C. Elevated core temperature increases cardiovascular strain, dehydration worsens blood viscosity, impair CNS function, and reduces cognitive and physical performance.
• D. Reduces dehydration effects.

Answer: (C)

When core temperature rises during exercise, the body's cooling demands push the cardiovascular system harder. Blood flow shifts toward the skin to dissipate heat, which reduces venous return and lowers stroke volume. To keep cardiac output up, the heart rate climbs, meaning the same exercise can feel harder and fatigue sets in sooner. Dehydration compounds this by losing plasma volume, thickening the blood, and worsening blood viscosity, making it harder to deliver blood efficiently and to continue sweating for cooling. The brain is sensitive to heat and reduced blood volume, so central nervous system function can decline, leading to slower reaction times, poorer concentration, and diminished decision-making. Altogether, hyperthermia tends to impair both cognitive and physical performance rather than improve or maintain it.