[Research Review] Study on Heat Acclimation Training for Marathon Runners: Plasma Volume Expansion and Core Temperature Adaptation — Elite Athlete Physiological Characteristics (Article 1138)

Source Reference: Journal of Applied Physiology • International Scientific Research Review Series

This article explores the physiological mechanisms of heat acclimation training on plasma volume expansion and core temperature regulation adaptation in marathon runners.

Physiological Mechanisms of Plasma Volume Expansion

Repeated heat exposure stimulates the kidneys and endocrine system to release antidiuretic hormone and aldosterone, prompting the body to retain more water and sodium ions, thereby expanding plasma volume. With increased plasma volume, under the same cardiac output, skin blood flow and muscle blood flow can both receive more adequate supply simultaneously—this is precisely the key to how heat adaptation improves both “heat dissipation capacity” and “exercise performance”: before plasma volume expansion, the body must compete between “muscle blood supply” and “skin heat-dissipation blood supply”; after adaptation, this competition is substantially alleviated.

Core Temperature Regulation Adaptation Process

The complete heat adaptation process typically requires 10-14 days of repeated exposure. During the adaptation process, the following observations can be made:

• The core temperature threshold for sweat onset decreases (sweating begins earlier, heat dissipation response becomes more sensitive)
• Sweat rate per unit time increases, but sodium ion concentration in sweat decreases (reducing electrolyte loss)
• At the same exercise intensity, the rise in core temperature becomes smaller, and resting heart rate decreases

Heat Adaptation Days and Physiological Indicator Changes (Illustrative)

Core Scientific Conclusions and Practical Recommendations

• Exposure Methods: Adaptation can be accelerated through actual hot-environment training, or by adding passive heat exposure via hot baths/saunas after training in a mild environment
• Electrolyte Supplementation: Sweat volume increases substantially during the adaptation period; sodium and fluid intake frequency should be increased to avoid the risk of hyponatremia
• Progressive Approach: Exercise intensity should be reduced during the initial phase of heat adaptation training to avoid the risk of heat stroke from simultaneous spikes in core temperature and cardiovascular load
• Adaptation Decays: Heat adaptation effects gradually diminish approximately 1-3 weeks after cessation of exposure; the primary adaptation period for pre-race heat acclimation should be scheduled within 2 weeks before competition

Common Research Q&A (FAQ)

Q: Is heat acclimation training suitable for all marathon runners?

A: The benefits are most pronounced for athletes planning to compete in hot, humid environments. If the race venue has a cool climate, the marginal benefits of heat acclimation diminish, but plasma volume expansion itself still provides positive benefits for general endurance performance.

Q: Can sauna sessions replace actual hot-environment training?

A: It can serve as a supplementary method—passive heat exposure can indeed induce partial adaptation responses—but it cannot fully replace the training-specific adaptations that occur when “exercise + heat” occur simultaneously. It is recommended to combine both approaches.

References and Academic Citations

1. Journal of Applied Physiology — Research directions related to heat adaptation and plasma volume regulation mechanisms.
2. Scandinavian Journal of Medicine & Science in Sports — Literature on the effects of heat acclimation training interventions in endurance athletes.

Further Reading

• Research Review: Study on Heat Acclimation Training for Marathon Runners: Plasma Volume Expansion and Core Temperature Adaptation — Elite Athlete Physiological Characteristics (Article 265)
• Research Review: Study on Heat Acclimation Training for Marathon Runners: Plasma Volume Expansion and Core Temperature Adaptation — Elite Athlete Physiological Characteristics (Article 976)
• Research Review: Study on Heat Acclimation Training for Marathon Runners: Plasma Volume Expansion and Core Temperature Adaptation — Latest Academic Literature Review and Training Practice (Article 1369)
• Research Review: Study on Heat Acclimation Training for Marathon Runners: Plasma Volume Expansion and Core Temperature Adaptation — Latest Academic Literature Review and Training Practice (Article 478)