Research Review: Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Temperature Adaptation in Marathon Runners: A Study of Elite Athlete Physiological Characteristics (No. 1318)

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. After plasma volume increases, at the same cardiac output, both skin blood flow and muscle blood flow can receive more adequate supply simultaneously—this is the key to how heat adaptation can improve both “heat dissipation capacity” and “athletic performance”: before plasma volume expansion, the body must compete between “muscle blood supply” and “skin heat dissipation blood supply”; after adaptation, this competition is significantly alleviated.

Core Temperature Regulation Adaptation Process

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

• The body temperature threshold for sweat initiation 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 body temperature is smaller, and resting heart rate decreases

Heat Acclimation Days and Physiological Indicator Changes (Illustrative)

Key Scientific Conclusions and Practical Recommendations

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

Common Scientific FAQs

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 location 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 saunas replace actual heat training?

A: They 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 acclimation 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.

Related Reading

• Research Review: Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Temperature Adaptation in Marathon Runners: A Study of Elite Athlete Physiological Characteristics (No. 1000)
• Research Review: Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Temperature Adaptation in Marathon Runners: A Study of Elite Athlete Physiological Characteristics (No. 1177)
• Research Review: Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Temperature Adaptation in Marathon Runners: A Study of Elite Athlete Physiological Characteristics (No. 1435)
• Research Review: Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Temperature Adaptation in Marathon Runners: A Study of Elite Athlete Physiological Characteristics (No. 1408)