Video·3 min read·May 2026

Harnessing the Power of Contrast: Insights from Winter Swimming Research

Sauna|Cold Therapy|Mechanisms • 3 min read • Based on research by B. DugueÂ and E. LeppaÈnen (2000)

Imagine stepping into a warm sauna, the heat enveloping you like a comforting embrace. Moments later, you plunge into icy water, a rush of cold awakening your senses. This contrast, while jolting, holds profound benefits for your body and mind. As wellness practices evolve, contrast therapy—combining heat and cold exposure—has gained attention for its potential to enhance recovery, resilience, and overall well-being.

A recent study by Dugue and Leppänen delves into the physiological adaptations of habitual winter swimmers, revealing how their bodies respond to thermal stress. By examining the interplay between sauna use and cold water swimming, we can uncover valuable insights into how these practices can support our health.

The Role of Cytokines in Our Immune Response

Cytokines are signaling molecules that play a crucial role in our immune system. They help regulate inflammation and communicate between cells, particularly during stress. In the study, researchers found that regular winter swimmers had higher baseline levels of interleukin-6 (IL-6), a type of cytokine, compared to those who were inexperienced in winter swimming.

This elevated level of IL-6 suggests that habitual exposure to cold water may enhance the immune response, equipping the body to better handle stress. By regularly engaging in contrast therapy, you may be training your immune system to become more resilient, promoting recovery and longevity.

Cortisol: The Stress Hormone and Its Adaptive Mechanisms

Cortisol, often referred to as the stress hormone, plays a key role in how our bodies respond to challenges. The study highlighted that habitual winter swimmers exhibited significantly greater cortisol responses to thermal stress compared to inexperienced swimmers. This indicates that their bodies are better adapted to handle the stress of extreme temperatures.

This adaptive mechanism means that regular exposure to thermal stress, through practices like sauna and cold water immersion, can enhance your body’s ability to manage stress more effectively. This is not just about physical endurance; it translates into a clearer mind and a more balanced emotional state.

Practical Applications for Your Wellness Rituals

Understanding these physiological responses allows us to integrate sauna and cold exposure into our wellness protocols intentionally. The findings suggest that incorporating regular contrast therapy can enhance our immune response and improve our resilience to stress.

As you design your wellness rituals, consider alternating between heat and cold exposure. Start with a sauna session to relax and open your pores, followed by a brief cold plunge. This combination can help you cultivate equilibrium in your body and mind, enhancing your overall sense of well-being.

Key Takeaways

Regular contrast therapy may enhance your immune response by increasing cytokine levels, such as IL-6.
Adapting to thermal stress can improve your body's ability to manage cortisol, leading to better stress resilience.
Incorporate sauna and cold water immersion into your wellness rituals to cultivate balance and recovery.

Based on: Adaptation related to cytokines in man: effects of regular swimming in ice-cold water
B. DugueÂ and E. LeppaÈnen (2000). Clinical Physiology

Contrast Collective • Science-backed wellness

Wim's Wise Words

A second take, from someone who's lived it.

🧊 Wim's Wise Words

Adaptation related to cytokines in man effects of regular swimming in

What the Body Learns From Ice

There's a question that sits at the heart of contrast therapy and cold exposure practice: does your body actually change, or does it just get better at tolerating discomfort? Dugué and Leppänen asked exactly that in 2000, and what they found in a Finnish sauna by a frozen lake tells us something important about the difference between coping and adapting.

The study is straightforward in design. Habitual winter swimmers — people doing this more than once a week for an average of seven and a half years — versus people with no recent experience. Same protocol: fifteen minutes in a 95-degree Celsius sauna, a brief walk through sub-zero air, thirty seconds in ice-cold water, walk back. Blood draws before and after. The question: how differently do these two groups respond at a biochemical level?

The Core Finding — And Why It Matters

The experienced swimmers had significantly higher baseline IL-6 at rest. Their cortisol response to the thermal stress was dramatically larger. And here's the crucial part: when researchers stimulated blood cells with a bacterial toxin (LPS) to see how aggressively the immune system would respond, the inexperienced swimmers showed a sharp suppression after the thermal stress. Their immune system, essentially, was rattled. The experienced swimmers? Their response tended to increase.

That's the adaptation. Not reduced sensitivity — enhanced readiness. The veterans weren't just tolerating the cold. They were using it.

The body doesn't get better at surviving cold. It gets better at learning from it. That's a different thing entirely.

How This Compares to Other Research

The 2010 paper on cold adaptation types in humans cites this study directly, and for good reason — it's one of the clearest early demonstrations that repeated thermal stress produces genuine systemic adaptation rather than just habituation. A 2025 review on winter swimming confirms the pattern holds: chronic cold exposure shifts immune function in a direction that looks more like trained readiness than blunted response.

What's particularly interesting is the soluble IL-6 receptor finding in women. Experienced female swimmers had significantly lower IL-6sR than inexperienced women. Less soluble receptor circulating in the blood means the IL-6 signal is more efficient — the molecule has fewer decoys to bind to and more chance of reaching its target. Higher baseline IL-6, more potent signaling. The system isn't just producing more — it's operating more cleanly.

Where Experts Land

There's broad agreement that short-term cold exposure creates a neuroendocrine cascade — cortisol, ADH, adrenaline, leukocyte mobilization. That's well established. The debate is about long-term adaptation. Some researchers frame elevated baseline IL-6 as a chronic inflammatory signal — a warning sign, not a benefit. Dugué and Leppänen's data complicates that reading. The experienced swimmers were subjectively healthy, functioning well, with a profile that looks more like a trained athlete than an inflamed one. Context matters enormously.

The Practical Recommendation

Consistency over intensity. Seven and a half years of average practice is what produced these adaptations. Not heroic single sessions. Not extreme durations. Regular, repeated exposure — more than once a week, across winters, year after year. If you're new to cold exposure, your immune system will initially be stressed by the stimulus. That's expected. Give it time. The adaptation Dugué and Leppänen documented doesn't happen in a month.

The Surprising Connection

The significant correlation between delta-cortisol values and baseline IL-6 concentrations is easy to overlook, but it's one of the more interesting findings here. The people with higher baseline IL-6 — the adapted swimmers — were also the ones whose cortisol spiked most dramatically during the thermal stress. Not less. More. We tend to think of stress adaptation as dampening the stress response. But this suggests something subtler: the adapted body responds more robustly, not because it's overwhelmed, but because it's trained to mobilize quickly and recover efficiently. The signal is sharper. The recovery is faster. That's what seven years of ice swimming looks like on a blood panel.

Adaptation related to cytokines in man: effects of regular swimming in ice‐cold water

Harnessing the Power of Contrast: Insights from Winter Swimming Research

The Role of Cytokines in Our Immune Response

Cortisol: The Stress Hormone and Its Adaptive Mechanisms

Practical Applications for Your Wellness Rituals

Key Takeaways

Related articles

Effect of winter swimming on hematological parameters

Effect of regular winter swimming on blood morphological, rheological, and biochemical indicators and activity of antioxidant enzymes in males

Winter swimming is it possible to develop adaptation to cold temperature