By Ana Espino | Published on June 29, 2026 | 4 min read
With climate change and the increasing frequency of
heatwaves, engaging in physical activity in hot environments has become a
growing concern for both athletes and professionals exposed to strenuous
physical work. Although the decline in performance during exercise in the heat
is well recognized, the physiological mechanisms involved and the most
effective strategies for minimizing their impact continue to be the focus of
extensive research.
In a landmark review published in Physiological Reviews,
Periard and colleagues provide a comprehensive overview of current knowledge on
the effects of heat stress during exercise. The authors examine the mechanisms
of thermoregulation, the impact of dehydration on physical performance, and the
main strategies for reducing heat-related health risks.
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Rising Body Temperature Progressively Limits Physical
Performance
During prolonged exercise, the body generates a substantial
amount of heat. To maintain an internal temperature compatible with normal
organ function, it activates several defense mechanisms, particularly sweating
and cutaneous vasodilation, which promote heat dissipation. However,
when environmental conditions become excessively hot or humid, these mechanisms
become less effective, leading to a progressive increase in core body
temperature.
This hyperthermia affects multiple physiological
systems. The cardiovascular system is placed under considerable strain as it
attempts to supply blood simultaneously to the working muscles and the skin,
while both the central nervous system and skeletal muscles experience reduced
functional capacity. The result is earlier fatigue, diminished endurance, and
impaired athletic performance, effects that become even more pronounced as
dehydration develops. Fluid losses through sweating reduce blood volume, impair
the body's cooling capacity, and further increase thermal stress.
Beyond performance impairment, prolonged exposure to heat
can lead to potentially serious heat-related illnesses, ranging from muscle
cramps and heat exhaustion to exertional heat stroke, a true
medical emergency requiring rapid cooling to minimize neurological damage and
multiple organ complications.
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Heat Acclimatization and Cooling Strategies: The
Cornerstones of Prevention
The authors emphasize that several measures can effectively
reduce the harmful effects of heat exposure. Progressive heat
acclimatization is one of the most effective interventions. After several
days of repeated exposure, the body improves its sweating capacity, expands
plasma volume, and becomes more efficient at dissipating heat.
Appropriate hydration also helps preserve
thermoregulatory function, although the optimal strategy for replacing fluid
losses remains the subject of ongoing debate.
Various cooling techniques, applied before or during
exercise, can also improve heat tolerance, particularly during competitions
held in challenging environmental conditions. However, the authors point out
that the effectiveness of these interventions depends on the type of activity,
the prevailing climate, and the individual characteristics of each athlete.
This review confirms that exercising in extreme heat is not
merely a challenge to athletic performance but also a significant public
health concern. In the context of global warming, a better understanding of
thermoregulatory mechanisms and the appropriate implementation of preventive
strategies will be essential to reduce health risks among both athletes and
workers exposed to high temperatures.
About the author – Ana Espino
PhD in Immunology, specialized in Virology
As a scientific writer, Ana is passionate about bridging the gap between research and real-world impact. With expertise in immunology, virology, oncology, and clinical studies, she makes complex science clear and accessible. Her mission: to accelerate knowledge sharing and empower evidence-based decisions. 
