Video·3 min read·May 2026

Understanding Cold Tolerance: Insights from Contrast Therapy Research

Cold Therapy • 3 min read • Based on research by Aklima Khatun, Sakura Ashikaga, Hisaho Nagano, Md Abdul Hasib, Akihiro Taimura (2016)

The body’s response to temperature changes is a fascinating aspect of our physiology. Many of us have experienced the invigorating bite of cold water or the soothing heat of a sauna, yet we may not fully understand how these experiences impact our bodies. Recent research sheds light on how different ethnic backgrounds influence our tolerance to cold exposure, particularly through a mechanism known as cold-induced vasodilation (CIVD).

This study, comparing Bangladeshi and Japanese participants, reveals significant differences in how our bodies react to cold temperatures. By exploring these differences, we can better tailor our wellness practices to enhance recovery and resilience.

The Science of Cold-Induced Vasodilation

Cold-induced vasodilation (CIVD) is an intriguing physiological response where blood vessels dilate when exposed to cold temperatures. This reaction increases blood flow to the skin, which can help protect against cold injuries. In a comparative study involving eight Bangladeshi and fourteen Japanese participants, researchers found that the Japanese group exhibited a higher tolerance to cold exposure.

Specifically, the Japanese participants had an average starting skin temperature of 34.62 °C, compared to 33.04 °C for the Bangladeshi group. After immersion in cold water, the Japanese participants experienced a quicker rise in temperature, achieving this in an average of 3.72 minutes, while their Bangladeshi counterparts took 5.35 minutes. This suggests that acclimatization to colder climates influences our body’s ability to manage cold exposure.

Cultural and Climatic Influences on Cold Tolerance

The differences observed in the study can be attributed to the diverse climates of Bangladesh and Japan. Bangladesh, with its tropical monsoon climate, presents milder winters and hot, humid summers. In contrast, Japan’s temperate climate offers a distinct seasonal variation, leading to a greater exposure to cold over time. This acclimatization may enhance the body’s physiological responses to cold, resulting in improved tolerance.

Understanding these ethnic differences is vital as it can inform how we approach cold exposure in our wellness routines. For instance, those from warmer climates may need to adapt their cold exposure practices gradually, allowing their bodies to develop the necessary resilience.

Practical Implications for Wellness Practices

The insights from this research can enhance our approach to contrast therapy, which blends hot and cold exposure for recovery and longevity. Knowing that individuals have varying tolerances to cold can guide how we create our wellness protocols. For example, a gradual introduction to cold exposure—starting with shorter durations in cooler water—can be beneficial for those less accustomed to it.

Moreover, incorporating regular cold immersion into your routine can promote resilience and clarity. Whether through cold showers or ice baths, these practices can foster a sense of stillness and equilibrium in the body, enhancing overall recovery and well-being.

Key Takeaways

Cold-induced vasodilation is a key physiological response that can enhance recovery during cold exposure.
Cultural and climatic backgrounds significantly affect individual tolerance to cold, informing personalized wellness practices.
Gradual acclimatization to cold exposure can foster resilience and improve overall well-being.

Based on: Cold-induced vasodilation comparison between Bangladeshi and Japanese natives
Aklima Khatun, Sakura Ashikaga, Hisaho Nagano, Md Abdul Hasib, Akihiro Taimura (2016). Journal of Physiological Anthropology

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Cold-induced vasodilation comparison between Bangladeshi and Japanese

What This Paper Is Actually Saying

Here's the core claim: where you're born and raised shapes how your body handles cold — not just culturally, not just psychologically, but at the level of vascular physiology. Bangladeshi men, raised in a tropical monsoon climate averaging 25 degrees Celsius year-round, took significantly longer to trigger cold-induced vasodilation than their Japanese counterparts, who grew up in a temperate country with genuine winters. Not slightly longer. Over a minute and a half longer for the vascular response, and more than five minutes longer for the sensation rise. That's a measurable difference in how quickly the body recognizes and responds to a cold threat.

Cold-induced vasodilation — CIVD — is your body's paradoxical defense against freezing. When you immerse a finger in ice water, vessels first constrict to preserve core temperature. But hold it long enough and the vessels dilate, flooding the tissue with warm blood. It's counterintuitive: the body deliberately sends heat to the thing that's losing heat. The mechanism protects against cold injury. Japanese participants triggered this response nearly two minutes sooner, suggesting their vascular systems had been conditioned — through years of seasonal cold exposure — to engage this protective cascade faster.

Your vascular system is not fixed. It's a trained organ, shaped by every winter you've ever lived through.

Where the Research Agrees — and Gets Complicated

This finding fits neatly into a broader pattern. A 2025 review of cold adaptation studies across populations confirms that polar natives consistently show superior CIVD responses compared to tropical indigenes. The 1996 CIVD study in the knowledge base adds another dimension: older men show delayed CIVD onset compared to younger men. So we have at least two variables shaping the same response — climate background and age. The 2023 Japanese cohort study goes deeper, using wavelet analysis to distinguish between endothelial nitric oxide-dependent, eNO-independent, and neurogenic vascular activity. That level of mechanistic resolution is something the 2016 Khatun study couldn't achieve with finger temperature measurements alone.

Where experts diverge is on the question of reversibility. How long does it take a Bangladeshi person living in Japan to acquire Japanese-like CIVD responses? The Bangladeshi subjects in this study had been in Japan for an average of 2.5 years — and they still showed significantly different responses. That's worth sitting with. Climate acclimatization may require longer than we assume, or it may be that some aspects of cold adaptation are tied to developmental exposure during childhood and adolescence rather than current living conditions.

The Practical Recommendation

If you're from a warm climate and you're building a cold exposure practice, start slower and stay more conservative for longer than you think necessary. Your CIVD response is genuinely less trained. What feels like a threshold you should push through may actually be your body working harder than someone raised in a cold climate just to achieve the same protective response. Gradual progression isn't weakness — it's physiology.

The Surprising Connection

Here's what stops me: the same paper that documents slower CIVD in tropical natives also references research showing those same individuals have weaker vasoconstriction after the first CIVD wave. The temperate body doesn't just respond faster — it oscillates more efficiently between constriction and dilation. That oscillation is the training. Every winter is a repetition. Every cold season is another cycle that teaches the vasculature to move fluidly between protection and perfusion. Contrast therapy, done consistently, may be doing the same thing in accelerated form — not just building tolerance to cold, but training the vascular system to oscillate with precision.

Cold-induced vasodilation comparison between Bangladeshi and Japanese

Understanding Cold Tolerance: Insights from Contrast Therapy Research

The Science of Cold-Induced Vasodilation

Cultural and Climatic Influences on Cold Tolerance

Practical Implications for Wellness Practices

Key Takeaways

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