The health benefits of heat exposure and raising our body temperature have been well documented. Sauna use in particular has been studied extensively, revealing a range of physiological benefits and demonstrating major improvements to metrics of cardiovascular health and systemic inflammation.
Studies conducted in Finland, some might say the home of sauna (unless you're from Estonia!)showed a linear relationship between frequency of sauna use and the reduction of all cause mortality, from cardiovascular disease to cancer. We also see a reduction in incidences of Alzheimers and Dementia attributed to what is known as hyperthermic(getting hotter than normal) conditioning.
From a physical training perspective, the value comes from the fact that heat stress exposure provides a significant boost to human growth hormone, which is imperative for driving growth and repair to muscles, ligaments and tendons. In addition to this, proteins known as "heat shock" proteins are also produced in cells through this "hyperthermic stress" and have been shown to induce repair of other damaged proteins within the body.
So it then looks clear that regular controlled hyperthermic stress should be a key part of any lifestyle focused on health and longevity. It would also be a valuable addition to the recovery phase of any training program.
A little bit about the immune system...
However, what has compelled me to write this article about heat exposure is the role and mechanistic relationship it has with our immune system. A relationship that truly warrants more knowledge exposure, and one that is of immense value during these pandemic days.
Now, our immune system has two components. The" innate" immune system is our first line of defence against anything that invades our body(known as "antigens") and is supported by the second component, the "adaptive" immune system. The adaptive part is only required in the event of the innate portion becoming overwhelmed. It is where our immunological memory and corresponding responses to previously encountered invaders is derived from.
All antigens, from bacteria and viral pathogens, to pollen, are confronted by the innate immune system upon entry to the body. It is the effectiveness of that system that can determine the development of any subsequent infection or the prognosis and outcome of any related disease if one should occur.
Now, a key component and actual first responder of the innate immune system is a molecular protein called an "Interferon". Interferons act as an alarm system which alert and stimulate immune cells and processes to get to work, defending the body of the invading antigen. Essentially "interfering" with the viral process.
This process is more relevant now than ever as early in the Sars Cov 2 pandemic, studies identified a clear association between early Interferon prevalence and Covid 19 outcomes and research has shown that part of the pathology of the virus is to actually suppress this part of the immune system as it tries to gain a foothold on the path to infection.
The innate immune system, naturally stronger and more reactive in children,
unfortunately declines with age(the reverse is actually true of the adaptive system) and has been seen as explanation as to why children have such better outcomes when encountering the virus.
So, an illuminating aspect of the immune system that most are unaware of and aptly relevant to this current viral adversary we are all facing.
Heat and the immune system...
Great, so where does the heat come in?
Well, it turns out we are not merely at the mercy of whatever standard of immune response granted to us, and we can actually influence to some degree the reactivity of that all important first line of defence.
It seems to be that Interferon activity-like many of its human hosts, greatly favours hotter climates. Core body temperature has been shown to stimulate interferon levels, with temperatures over 37 degrees displaying a significant increase.
Conversely, we've also learnt that viral pathogens prefer colder climates and heat seems to destabilise virus membranes, making the virus weaker and affecting functionality.
These two factors highlight how important raising core body temperature is in the process of defence against illness.
On one hand this should come as no surprise, as this is the purpose of our bodies creating a fever as a response to an infection, an adaptive defence mechanism that has persisted throughout the animal kingdom for millions of years. Heat has also been used specifically throughout human history by various cultures to treat respiratory infections in various forms, from saunas in northern europe, hammans (steam baths) in the middle east, to the sweat lodges of native American indians and the hot mud baths of the ancient Greeks.
What we can do to influence...
In terms of practical application, any rise in body temperature by any means would be beneficial, though the most energy efficient method physically would be in achieving that through the use of a sauna or hot bath. This is a term known as "hydrothermal therapy".
Exercising yourself into a sweat, with the goal of raising your body temperature could be counterproductive if your body requires energy to fight an illness, so wouldn't be advised in that context. However, in good health, would provide a synergistic effect when applied together with any form of hyperthermic stress.
In the studies, the bath water was at 40 degrees, so that suggests that would work, but in my personal experience, I find if I increase the bath temperature to just below physically intolerable (obviously don't burn yourself!) it can stimulate a similar physical reaction I get from spending 15 to 20 mins in a 90 degree sauna.
See how your own body feels of course and adjust accordingly, but getting to the point where your body is producing sweat would be a good indication that you've hit the right level of intensity.
Duration? 10 to 20 mins seems to be optimal and ideally followed by some brief cooling -this was actually shown to enhance immune stimulation further.
So there you have it, a nice, simple, pleasurable (at least for the first 10 minutes!), accessible practice that we can all utilise to keep our bodies in optimal human health, revving up our immune system to work more effectively. One that could have a significant influence on the outcome of any viral exposure our human bodies may face.
Bring on the heat.
Love, always
Steven
Sources below:
Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study | BMC Medicine
Sauna bathing and systemic inflammation - PubMed
https://pubmed.ncbi.nlm.nih.gov/29209938/
Pre-activated antiviral innate immunity in the upper airways controls early SARS-CoV-2 infection in children | Nature Biotechnology
Turning up the heat on COVID-19: heat as a... | F1000Research
Hydrothermotherapy in prevention and treatment of mild to moderate cases of COVID-19 - PubMed
https://pubmed.ncbi.nlm.nih.gov/33303302/
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