Longevity

Out Of The Frying Pan And Into The Freezer: Does Alternating Heat And Cold Benefit Your Health?

Posted on 12 October 2022

As saunas, cold showers and the like have grown in popularity for their reported physical and psychological benefits, so too has the idea of combining these practices. Many people advocate taking a cold shower or ice bath immediately after using the sauna or vice versa for increased benefit. This certainly isn’t a new practice. In some cultures, most famously in Finland, taking a plunge from the sauna into an icy lake is a time-honoured tradition. What’s the idea behind this, and is there any evidence to back it up?

Key Points:

  • Individually, heat and cold exposure seem to have multiple benefits including for cardiovascular health, immunity, temperature control and recovery from injury and exercise.
  • Alternating heat and cold exposure could allow people to experience the benefits of both practices for longer.
  • Science currently isn’t sure whether combining these practices amplifies their effectiveness.
  • Transitioning from a high to a low-temperature environment is dangerous for some people.

The Principal:

We previously covered in greater detail how exposure to extremes of both cold and heat can, individually, provide health benefits. Initially, high and low temperatures have opposite effects on the body. High temperatures cause more blood to be diverted towards the skin to aid heat dissipation, while cold temperatures result in blood being diverted away from the skin and extremities. This adaptation is plain to see, as skin visibly reddens or pales depending on the temperature. Heat also causes sweating, while cold temperatures trigger several responses to increase the heat generated by the body. One of these responses, shivering, is readily visible. Cells also begin to consume stored calories in order to generate additional heat, a process that mainly occurs in special fat tissue called brown fat.

Photo by HUUM on Unsplash

While hot and cold temperatures may trigger opposite responses, they can benefit health in similar ways. Both heat and cold adaptation strain the cardiovascular system, which improves cardiovascular health in the long term, and seem to mimic some of the beneficial effects of exercise. Furthermore, exposure to extremes of temperature increases the body’s ability to adapt to temperature changes in the future. Some research also suggests that, individually, extremes of temperature may have a variety of other benefits including improved immunity, reduced inflammation and accelerated healing of certain injuries.

There are several ways in which alternating between hot and cold temperatures, such as taking a cold shower in between saunas sessions, could carry additional benefits.
The first, most simple explanation is that exposure to cold makes the subsequent sauna session more enjoyable and tolerable, and vice versa. This allows people to spend longer at each extreme of temperature than they otherwise would.
Similarly, cold exposure may allow people to rapidly recover from the heat stress of a sauna session, allowing them to re-enter the sauna sooner.
It is also conceivable that alternating between two extremes of temperature could amplify the resulting health benefits. One plausible mechanism for this is that the metabolism benefits in some way from being forced to rapidly switch from one temperature response to the opposite response. Another is that the supply of blood to the skin and extremities also affects the delivery of oxygen, so rapid changes in oxygen supply could trigger beneficial signals in some tissues.

The Evidence:

While the effects of both sauna use and cold therapies have been studied, their benefits in normal, healthy people are not as well researched as we might like, as research in this area tends to focus on applications in high level sports. Studies looking at the combination of heat and cold therapies are uncommon. In particular, we need studies to investigate whether alternating bouts of heat and cold exposure are more beneficial together than they are individually.

We do know that following a sauna session by an ice water bath or cold shower puts greater strain on the heart when compared to cooling off at room temperature. One study found that in both normal people and patients suffering from heart disease, systolic blood pressure dropped during sauna use. When that sauna session was followed up with cold water immersion, systolic blood pressure increased more rapidly than in those who didn’t undergo cold water immersion.

Photo by Tobias Oetiker on Unsplash

Besides cardiovascular effects, some research suggests that alternating heat and cold stimulation can reduce muscle stiffness, and that the ratio of heating time to cooling time did influence the effectiveness (3 minutes of heating to 1 minute of cooling was found to be optimal). Studies have also looked at a treatment known as contrast water therapy, which involves alternating between hot and cold water baths, usually spending only a few minutes at a time in each. A meta-analysis of 13 such studies concluded that contrast water therapy did seem to quicken recovery from strenuous exercise. However, it didn’t appear to be any more effective than cold or warm water immersion by itself.

The Risks:

These practices aren’t safe for everyone. Most of the risks come from the sudden cold exposure, and apply primarily to people with cardiovascular disease and high blood pressure. Since cold temperatures cause peripheral blood vessels to narrow, blood pressure increases as does the workload of the heart, which could trigger a cardiac event. Type 1 and type 2 diabetics also need to be careful, since these conditions are associated with reduced ability to maintain body temperature during large temperature changes.

The Take-Home Message:

Alternating exposure to hot and cold temperatures is beneficial, but we don’t really know if it’s more beneficial than just one or the other by itself. People should make certain that it is safe for them to experience rapid transitions in temperature. Assuming you aren’t putting yourself at risk, there’s little reason not to try this practice. Many people report that makes the experience more pleasant, and it might carry additional benefits.


References

Effects of heat and cold on health, with special reference to Finnish sauna bathing: https://doi.org/10.1152/ajpregu.00115.2017

Effects of alternating heat and cold stimulation at different cooling rates using a wearable thermo device on shoulder muscle stiffness: a cross-over study: https://doi.org/10.1186%2Fs12891-022-05623-z

Contrast Water Therapy and Exercise Induced Muscle Damage: A Systematic Review and Meta-Analysis: https://doi.org/10.1371%2Fjournal.pone.0062356

Sauna, shower, and ice water immersion. Physiological responses to brief exposures to heat, cool, and cold. Part II. Circulation: https://pubmed.ncbi.nlm.nih.gov/2736002/

Acute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failure: https://doi.org/10.1177/2047487315594506

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