Saunas, Cold Plunges, and Exercise: The Adversity Habits That Slow Ageing

You probably already know that exercise is good for you. You may have heard that saunas have health benefits. Cold plunges have become increasingly popular among people interested in performance and longevity.

But do these things actually slow ageing at the cellular level? And if so, how much do they matter compared to diet and supplements?

Exercise: the most important longevity habit

A CDC-funded study found that people who exercise regularly — around 30 minutes of jogging five days a week — have telomeres that look 10 years younger than sedentary people. That's a decade of biological age difference from exercise alone.

But the type of exercise matters. While weight training is important for maintaining muscle mass, hormone levels, and mobility (all crucial for healthy ageing), the longevity evidence is strongest for aerobic exercise that gets you genuinely out of breath. Even 5 minutes of panting-level effort, three times a week, activates the cellular pathways associated with longer lifespan.

Saunas: not a luxury, a medical intervention

The evidence for sauna use is surprisingly robust. Studies on Finnish men — a population where most homes have saunas — have consistently shown that regular sauna use is associated with significantly reduced cardiovascular disease and lower overall mortality.

The mechanism appears to involve heat shock proteins — cellular defence proteins activated by heat stress that help maintain protein quality and protect against cellular damage. Regular sauna use essentially gives your cells a controlled thermal stress, activating hormetic repair responses similar to those triggered by exercise.

"Saunas are in my mind not even a question," says Sinclair. "They are proven to be beneficial for multiple reasons — heart disease and even long-term mortality."

Cold plunges: promising but less proven

The cold plunge evidence is more mixed. There's compelling theory — cold is a powerful hormetic stressor that activates cellular defence mechanisms and may improve muscle repair after exercise. There are anecdotal reports of improved mood, clarity, and energy. But the rigorous long-term human data simply doesn't yet exist to the same degree as it does for exercise and saunas.

The current evidence suggests cold exposure probably helps — and if you enjoy it, there's essentially no downside.

The key principle: prioritise what gets you breathless

"The combination of the easiest biggest impact you can have would be skipping meals," says Sinclair. "And then a close second would be exercise that includes losing your breath for at least five minutes three times a week." If you're not panting, you're not getting the full longevity benefit from your cardio session.