Finland

Sitting in a hot room
did what exercise was supposed to.

Sauna  ·  löyly  ·  Mechanism: vascular dilation

Finland has roughly three million saunas for five and a half million people. The sauna is not a spa add-on there. It is closer to a second kitchen.

The word for the burst of steam thrown onto the hot stones is löyly. The practice is built around that wave of heat and the slow climb in body temperature that follows.

Sessions run hot, often between seventy and a hundred degrees Celsius, and last five to twenty minutes at a stretch. Regular bathers go several times a week, year round.

What makes Finland useful to study is the consistency. Researchers there are not measuring an occasional treat. They are measuring a habit people keep for decades.

Heat forces the body to shed warmth, and the main way it does that is by widening blood vessels near the skin. Heart rate climbs, vessels relax, and blood moves the way it does during light to moderate exercise.

The signal that matters here is not sweat. It is what happens to the lining of the arteries when they are repeatedly asked to dilate.

A long-running cohort study from the University of Eastern Finland, led by Jari Laukkanen, followed thousands of middle-aged adults for two decades. People who used a sauna four to seven times a week had markedly lower rates of fatal cardiovascular disease than those who went once a week.

This is observational evidence, not proof that heat alone caused the difference. But a separate randomized trial in adults with coronary artery disease found that regular sauna sessions improved measures of vascular function, which points at the same dilation pathway rather than coincidence.

The how-to

You do not need a backyard sauna. The signal is repeated heat exposure that raises your core temperature, and most gyms and community pools already have a box that does it.

Find a dry sauna at a gym, YMCA, or pool. A day pass usually runs ten to twenty dollars; many memberships include it.
Start short. Five to ten minutes at a comfortable heat, once or twice a week, then build toward fifteen minutes as it stops feeling hard.
Drink water before and after, since you will lose fluid, and sit on a towel on the lower bench where it is cooler.
Expect to feel flushed and loose-limbed afterward, not wrung out. If you ever feel dizzy or your heart pounds, leave and cool down.
Safety: heat dilates blood vessels and can drop blood pressure, so step out if you feel faint. Skip the sauna if you are pregnant, have unstable heart disease, or have had a recent cardiac event, and clear it with your doctor first if you take blood pressure medication or have any heart condition. Never combine it with alcohol.

Tomorrow: Mexico and nopal
The breakfast pad on the plate before the eggs, and the fiber that changes what the meal does to your blood sugar.

See you then.