Beyond just recreational use, regular hot tub use can have a range of health benefits.
From improved cardiovascular health to mental well-being, this article highlights the science behind hot tub use, with links to published reports and further reading.
The Science of Heat Exposure
Before listing specific benefits from using a hot tub, it helps to first have an understanding of how exposure to heat affects us.
While in hot water, the body undergoes a series of physiological responses: core body temperature rises, blood vessels open up (a process known as vasodilation), and heart rate increases. All these are in response to the body's effort to manage temperature and attain homeostasis. Interestingly, all these can have a lasting effect on health, particularly with repeated exposure to heat over time.
Exposure to heat also causes heat shock proteins (HSPs) to be synthesised, which are crucial for repair and resistance to stress in cells. HSPs are induced due to stressors like heat and are responsible for protecting cells from damage, helping with protein folding, and improving overall cell health. This is one of the primary explanations for how heat therapy, like a hot tub, can be beneficial.
Cardiovascular Health
One aspect of hot tub use that has seen a lot of research is its effects on cardiovascular health. Soaking in warm water will dilate blood vessels, which increases blood flow and reduces blood pressure. A study published in The Journal of Physiology concluded that regular hot water immersion can lead to improved endothelial function (which, amongst other things, means that blood vessels expand and contract normally). This is particularly useful for individuals with hypertension or other cardiovascular illness.
Heat exposure, such as sitting in a hot tub, can enhance vascular compliance, which can enhance circulation and reduce strain on the heart. This can result in a lower rate of heart disease and stroke in the long term.
Muscle Recovery and Pain Relief
Athletes and fitness enthusiasts use hot tubs for muscle recovery, and for good reason. Heat and water buoyancy relax muscles, reduce inflammation, and relieve pain. A study published in the Journal of Science and Medicine in Sport demonstrated that hot water immersion after exercising greatly reduced muscle soreness and recovery times compared to passive rest. The warm heat from a hot tub increases blood flow to muscles, delivering them with oxygen and nutrients to aid in repair.
Additionally, water's buoyancy reduces gravity's influence, relaxing muscles and joints significantly. This is an excellent therapy for individuals with chronic pain syndromes, such as arthritis or fibromyalgia. Research in the Annals of the Rheumatic Diseases found that hydrotherapy treatments regularly eased pain and stiffness and enhanced physical function in osteoarthritis sufferers.
Mental Health and Stress Reduction
The psychological benefits from using a hot tub may be as significant as any physical benefits. Soaking in warm water has been shown to activate the parasympathetic nervous system, responsible for the body's "rest and digest" state. This can reduce levels of cortisol, a stress hormone, and bring about a state of relaxation and calm.
Andrew Huberman, the popular American neuroscientist and podcaster, has regularly pointed out how important stress management is to overall health, with chronic stress having a variety of negative effects ranging from impaired cognitive function to weakened immunity and increased risk for mental illness. By providing a space for relaxation and stress release, hot tubs can serve as a valuable resource for mental health.
A study in the Journal of Physiological Anthropology found that people who bathed regularly in hot water had lower anxiety and stress levels. Warm water therapy was also associated with better sleep, which is crucial for mental health. Sleep disturbances have been linked to a range of issues, from depression and anxiety to cognitive deficits. By promoting relaxation and reducing stress, use of a hot tub can indirectly improve sleep and mental health.
Metabolic and Immune Benefits
Recent studies have shown that exposure to heat, such as from a hot tub, has immune and metabolic advantages. Repeated exposure to heat has been shown to improve insulin sensitivity, which is important for blood sugar regulation. A study in JAMA Internal Medicine found that frequent use of saunas (which is comparable to hot tub use in terms of heat) was associated with a reduced rate of type 2 diabetes. While more research is needed to confirm these effects in hot tub use, the findings are promising.
Heat exposure also initiates the release of white blood cells, which play a crucial role in the body's immune system. The concept of "hormetic stress," describes how mild stressors can be good for the body. Heat exposure is a stressor that can enhance the body's resilience and immune system over time.
Skin Health
The benefits of hot tub use do not end with relaxation. Skin health is a beneficiary as well. Warm water opens pores, and a good clean can lead to improved skin texture and color. Enhanced blood flow to skin due to hot tub use can also result in a radiant, healthy glow. Be aware, however, that prolonged exposure to chlorinated water dries out skin. Showering after hot tub use and using a moisturiser to seal in moisture is recommended to combat this.
Safety Considerations
While the health benefits from using a hot tub are tempting, care should be taken with this activity. Prolonged exposure to high heat can lead to dizziness or heat stroke or to dehydration. Hot tub use should be kept to 15-20 minute sessions and water should be consumed before and after use to avoid dehydration. People with certain medical conditions, such as low blood pressure or heart disease, should see a doctor before using a hot tub.
In Conclusion
Scientific studies increasingly validate the health advantages of using a hot tub. Enhancing cardiovascular health and aiding in recovery from muscle strain, reducing stress levels and enhancing mental health are just a few of the benefits to be derived from consistent use. Insights from experts like Andrew Huberman contribute to knowledge about how and why hot tub use has such a positive influence, namely how heat exposure can trigger repair processes in cells and improve vascular health.
But, as with any health practice, moderation and caution are essential. By using hot tubs responsibly and in conjunction with other positive health practices, you can access the therapeutic value of heat exposure to improve overall well-being.
Whether you are an athlete looking to recover more quickly, a chronic pain patient, or simply a seeker of relaxation, the humble hot tub can be more than a relaxing soak—it can be a pathway to better health.
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