Heat and cold : what does the environment do to the marathon runner?

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Sports Science

Background:

• Marathon running presents significant physiological stress.
• High heat and humidity exacerbate this stress, impacting athlete performance and well-being.
• Existing research highlights the effects of heat and hydration on cardiovascular and thermoregulatory systems.

Purpose of the Study:

• To investigate the physiological mechanisms underlying decreased performance and increased fatigue during marathon running in hot conditions.
• To explore the impact of heat and dehydration on the cardiovascular system and thermoregulation.
• To examine the potential role of the central nervous system (CNS) and brain function in exercise fatigue.

Main Methods:

• Analysis of physiological responses during exercise in heat, including heart rate and core temperature.
• Assessment of hydration status and its effects on cardiovascular parameters like stroke volume and cardiac output.
• Review of recent research on hyperthermia, CNS function, and neurotransmission in relation to exercise fatigue.

Main Results:

• Elevated exercise heart rate and core temperature are observed at the same absolute intensity in the heat.
• Dehydration leads to reduced stroke volume, cardiac output, and blood pressure, impairing blood flow to muscles.
• Emerging evidence suggests hyperthermia may directly affect the CNS, potentially contributing to fatigue.

Conclusions:

• Heat and dehydration significantly impair marathon performance by affecting cardiovascular function and muscle blood flow.
• The central nervous system, particularly brain function and neurotransmission, may play a crucial role in exercise fatigue during prolonged heat exposure.
• Further research is needed to fully elucidate the complex interplay between environmental conditions, physiological responses, and central fatigue mechanisms.