Can saunas replace exercise? Cardiac science has the answer

Have you ever had this feeling: exhausted after work, with the "daily goal" in the fitness app glowing red, but you don't want to do anything and just want to lie down?

At this moment, the thought "After all, taking a sauna is good for the heart" pops into your mind - but you're not sure if it's true or if you're just making an excuse for yourself?

Scientists also think this question is worthy of serious study. In recent years, a group of cardiovascular researchers from Finland, the United States, and Europe have begun to systematically compare the effects of saunas and exercise on the heart. The conclusion... is indeed a bit surprising.

What Exactly Does a Sauna Do To The Heart?

Your body starts to experience heat stress when you enter a sauna that operates at 80 degrees Celsius. Your body remains inactive during this time yet your body undergoes a strong physiological response.

First, the skin blood vessels experience rapid dilation which leads to blood flowing into the outermost layer of the body. The heart has to increase its blood pumping speed so that it can keep blood pressure stable throughout the body. The body normally receives 5% to 10% of its blood volume during rest periods, but sauna usage increases this percentage to approximately 70%. The heart needs to pump 7 to 8 liters of blood to achieve skin cooling.

A study published in "Frontiers in Cardiovascular Medicine" in 2025 pointed out that the physiological reactions brought about by sauna bathing are "astonishingly similar" to those of moderate to high-intensity aerobic exercise - vasodilation, increased heart rate, increased stroke volume, and changes in arterial stiffness - these changes can also be observed during moderate-intensity exercise.

More specifically, the heart rate typically increases by 50% to 70% during sauna, which is basically the same as the heart rate level during moderate-intensity exercise.

That Major Finnish Study That Changed The Status of Saunas

To understand why saunas are taken seriously in the field of cardiac science, one must refer to a large-scale follow-up study conducted in eastern Finland over a period of more than 20 years - the Finnish Kuopio Ischemic Heart Disease Risk Factors Study (KIHD).

This study followed Finnish middle-aged men aged 42 to 60, recorded their frequency of sauna use, and then waited for 20 years to observe the differences in the incidence of heart disease.

 

The results are impressive:

• People who use the sauna 2 to 3 times a week have a 27% lower risk of cardiovascular death compared to those who use it only once a week.
• Those who use the sauna 4 to 7 times a week have a 50% lower risk of cardiovascular death and a 40% lower risk of all-cause mortality.
• People who soak for more than 19 minutes each time have a 52% lower risk of sudden death compared to those who use it for a shorter period.

This data remains significant even after adjusting for confounding factors such as physical activity level, smoking, and socioeconomic status.

In other words: The protective effect of saunas on the heart is not because people who love taking saunas are inherently healthier.

Sauna and Sports: Cooperation, Not Competition

At this point, it is necessary to clarify one thing: Science does not believe that saunas can "replace" exercise.

A randomized controlled trial published in the American Journal of Physiology in 2022 divided 47 participants with low physical activity levels and at least one cardiovascular risk factor into three groups: the pure exercise group, the exercise plus sauna group, and the control group. The study lasted for 8 weeks.

The results showed that the pure exercise group outperformed in terms of cardio-pulmonary endurance and body fat reduction; however, the exercise plus sauna group outperformed the pure exercise group in terms of a decrease in systolic blood pressure (−8.0 mmHg) and total cholesterol reduction.

That is to say, exercise does things that saunas cannot (improve maximal oxygen uptake, change body fat), while saunas "teach" exercise a lesson in terms of blood pressure and cholesterol. The combined effect of the two is better than any of them done alone.

What About Those Who "Can't Exercise"?

This is precisely what has excited the scientific community regarding saunas.

The latest comprehensive review study in 2025 pointed out that for people who are unable to engage in formal physical activities - such as the elderly, patients with osteoarthritis, those with mobility impairments, or those in the post-operative recovery stage - saunas offer the possibility of a "passive cardiovascular training".

In the same year, a study on patients with ischemic heart disease (a type of heart disease caused by insufficient blood flow in the coronary arteries and is one of the leading causes of death worldwide) found that after using saunas, these patients experienced cardiovascular improvements similar to those from light exercise: better blood flow, lower blood pressure, and more flexible blood vessels.

For these people, "being unable to exercise" used to mean that their cardiovascular conditions could only continue to deteriorate. Saunas might have opened a door for them.

The Operation Mechanism of a Sauna: What Happens Inside The Body?

The protective effect of saunas on the heart is currently believed to involve the following main pathways:

Activation of heat shock proteins (HSP) High temperatures trigger cells to produce heat shock proteins, which are responsible for repairing damaged proteins, clearing cellular waste, and resisting oxidative stress - these processes also occur during exercise and are an important mechanism for long-term protection of the cardiovascular system.

Improvement of endothelial function The endothelium is a layer of cells on the inner wall of blood vessels, responsible for regulating vessel dilation and blood flow. Repeated heat stress can improve endothelial function and reduce the risk of arteriosclerosis.

Continuous reduction of blood pressure Research has found that during the recovery period after saunas, both systolic and diastolic blood pressure decrease, and this effect is also reflected in daily life after regular use.

Regulation of the autonomic nervous system Saunas alternately stimulate the sympathetic and parasympathetic nerves, which helps to improve heart rate variability - this is an important indicator of heart health.

How Long And How Often To Soak For It To Be Effective?

Based on existing research, the following are evidence-supported usage recommendations:

• Temperature: Traditional Finnish saunas are approximately 80-100°C, and infrared saunas are approximately 50-65°C; both are supported by research.
• Session Duration: 15-20 minutes can trigger significant physiological responses; exceeding 30 minutes is not necessarily better and increases the risk of dehydration.
• Frequency: Observable cardiovascular benefits begin to appear 2-3 times per week; more than 4 times per week yields more significant effects.
• Regularity is more important than occasional use: All studies emphasize that cardiovascular protective effects come from long-term adherence, not occasional behavior.

Who Should Not Use a Sauna?

The following groups should consult a doctor before using a sauna:

• Patients who have recently had a myocardial infarction or severe aortic stenosis (this is a clear contraindication in sauna studies)
• Patients with uncontrolled hypertension
• Patients with epilepsy
• Pregnant women
• Patients taking certain antihypertensive medications (the blood pressure-lowering effect of sauna may be additive).

In summary: Can sauna replace exercise?

It can't completely replace it—but for your heart, it can do far more than you might think.

The exercise program leads to body fat reductions and muscle mass increases and VO2 max improvements which no sauna treatment can match. The sauna provides no benefits to your weight loss or athletic performance goals.

The sauna provides actual health benefits which scientists have proven through extensive research. The benefits of sauna use are especially important for people who cannot participate in physical exercise.

For most healthy individuals, the ideal combination is to incorporate sauna into your exercise routine—exercise improves your body composition, while sauna further lowers blood pressure and cholesterol, creating a synergistic effect.

Next time you're too lazy to exercise, a sauna is certainly not an excuse. But if you're already working hard to maintain your heart health, sauna is definitely a tool worth taking seriously.

If you have limited space at home but still want to use a sauna, we recommend the Portable Home Steam Sauna Box. It's perfect for long-term use in small spaces.