Passive heat therapy offers cardiovascular and immune perks similar to exercise
By isabelle // 2025-07-31
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  • Modern science confirms traditional heat therapies like saunas and hot baths trigger cardiovascular and immune responses similar to mild exercise.
  • A 2024 study found that hot tubs produce the strongest physiological changes, nearly doubling cardiac output like moderate exercise does.
  • Heat stress mimics exercise by dilating blood vessels, improving heart function, and reducing chronic inflammation.
  • Heat therapy may protect brain cells from diseases like Alzheimer’s and enhance athletic performance by maintaining muscle warmth.
  • Experts warn heat therapy isn’t safe for everyone (those with heart conditions should avoid it), but it’s a viable alternative for those who can’t exercise.
For centuries, cultures worldwide have harnessed the healing power of heat, from ancient Mesoamerican sweat lodges to Scandinavian saunas. Now, modern science confirms what traditional healers long suspected: Passive heat therapy, including hot baths, saunas, and hot tubs, triggers cardiovascular and immune responses strikingly similar to mild-to-moderate exercise. Recent research from the University of Oregon reveals that when body temperature rises, the body reacts with sweating, blood vessel dilation, and increased heart output, mirroring the effects of aerobic activity. While exercise remains the gold standard, heat therapy offers a viable alternative for those unable to engage in regular physical activity, with benefits ranging from lowered blood pressure to enhanced brain protection.

Heat vs. exercise: A surprising overlap

A 2024 study published in the American Journal of Physiology compared three heat therapies: hot water immersion (40.5°C for 45 minutes), traditional Finnish sauna (80°C in 10-minute intervals), and far-infrared sauna (45–65°C for 45 minutes). Researchers found that hot tubs induced the most significant physiological changes, including a 1.1°C rise in core temperature and a near-doubling of cardiac output, which is comparable to moderate exercise. "Both hot tubs and saunas, when done correctly and consistently, are associated with improved health," said Dr. Christopher Minson, the study’s lead author. "Part of this response is because when our body temperature is elevated for a period of time, it produces effects in heart rate, sweating, and the distribution of blood throughout the body that are similar effects of those of mild-to-moderate exercise.” The mechanisms are clear: Heat stress dilates blood vessels, forcing the heart to pump harder to maintain circulation. This mimics the cardiovascular strain of exercise, potentially strengthening the heart and improving vascular function over time. Heat therapy also sparks an immune response resembling post-exercise inflammation. In the study, hot water immersion increased interleukin-6 (IL-6), a cytokine that triggers anti-inflammatory pathways. This temporary inflammation may reduce chronic low-grade inflammation linked to heart disease and metabolic disorders.

Beyond the heart: Brain and performance boosts

Heat therapy’s benefits extend beyond the cardiovascular system. A review in Frontiers in Physiology noted that passive heat increases heat shock proteins, which protect brain cells from toxic protein buildup associated with Alzheimer’s and Parkinson’s. Meanwhile, athletes may gain an edge: A meta-analysis found that maintaining muscle temperature between warm-ups and workouts using heated garments improved power output. While the infrared saunas touted by wellness influencers operate at lower temperatures, they still promote relaxation and circulation. However, hot tubs and traditional saunas deliver more pronounced physiological effects. However, experts advise caution: Heat therapy isn’t for everyone. Those with unstable heart conditions, severe hypertension, or infections should avoid it. For beginners, it is wise to start with 10-minute sauna sessions, gradually increasing to 20 or 30 minutes a few times per week. Exercise remains unparalleled for health, but for those sidelined by injury, illness, or time constraints, heat therapy offers a compelling alternative. "Heat therapy is good supplementation," said Jessica Atencio, a co-author of the Oregon study. Whether it's through a steamy bath or a sauna session, turning up the heat might just be the next best thing to breaking a sweat. Sources for this article include: TheEpochTimes.com Journals.Physiology.org Independent.co.uk Eurekalert.org
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