【Research Review】Study on the Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Body Temperature Adaptation in Marathon Runners: A Biomechanical Quantitative Experiment Report (No. 862)

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

This article explores the physiological mechanisms of heat acclimation training on plasma volume expansion and core body 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 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.

Adaptation Process of Core Body Temperature Regulation

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

• The body temperature threshold for sweat onset decreases (sweating begins earlier, and the 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 Adaptation Days and Changes in Physiological Indicators (Schematic)

Core Scientific Conclusions and Practical Recommendations

• Exposure Method: Adaptation can be accelerated through actual hot-environment training, or by arranging additional passive heat exposure via hot baths/saunas after training in a mild environment
• Electrolyte Supplementation: During the adaptation period, sweat rate increases substantially; the frequency of sodium and water supplementation 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 heatstroke caused by simultaneous spikes in core body temperature and cardiovascular load
• Adaptation Fades: The effects of heat adaptation gradually diminish approximately 1-3 weeks after cessation of exposure; the main adaptation period for pre-race heat acclimation should be scheduled within 2 weeks before the 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 and humid environments. If the competition venue has a cool climate, the marginal benefits of heat adaptation will be reduced, but plasma volume expansion itself still has positive effects on general endurance performance.

Q: Can saunas 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” happen simultaneously. It is recommended to use both in combination.

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 related to the effects of heat acclimation training interventions in endurance athletes.

Related Topic Reading

• 【Research Review】Study on the Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Body Temperature Adaptation in Marathon Runners: A Biomechanical Quantitative Experiment Report (No. 619)
• 【Research Review】Study on the Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Body Temperature Adaptation in Marathon Runners: A Biomechanical Quantitative Experiment Report (No. 919)
• 【Research Review】Study on the Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Body Temperature Adaptation in Marathon Runners: A Biomechanical Quantitative Experiment Report (No. 511)
• 【Research Review】Study on the Effects of Heat Acclimation Training on Plasma Volume Expansion and Core Body Temperature Adaptation in Marathon Runners: A Biomechanical Quantitative Experiment Report (No. 1192)