“A sauna session is as good as a workout.”

The research found this

Heat makes the heart work harder. In 50 adults using saunas with water thrown on the stones, heart rate climbed from 79 to 121 beats a minute across a 10-minute bout.1Source 1 · Clinical trialTemperature and humidity independently influence thermoregulatory responses during Finnish sauna bathingLaatikainen-Raussi I, Mikkola T, Ihalainen JK, et al.. Temperature, 2026.Read the paper ↗PubMed ↗ Another study put 19 adults in a 93°C sauna for 25 minutes, and their heart rate and blood pressure rose steadily to a cardiac load the authors matched to 60 to 100 watts on a bike.2Source 2 · Clinical trialThe blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exerciseKetelhut S, Ketelhut R. Complementary Therapies in Medicine, 2019.Read the paper ↗PubMed ↗

The extra pumping comes from speed alone. In a head-to-head test in 20 young adults, three 10-minute bouts in a traditional sauna raised cardiac output from 5.0 to 7.3 liters a minute while the volume pumped with each beat went only from 70.2 to 71.2 milliliters.3Source 3 · Crossover trialComparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalitiesAtencio JK, Reed EL, Wiedenfeld Needham K, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2025.Read the paper ↗PubMed ↗ In long passive-heating experiments, blood flow to the skin can take more than half of the heart's output as the body sheds heat.4Source 4 · ReviewHuman Cardiovascular Responses to Passive Heat StressCrandall CG, Wilson TE. Comprehensive Physiology, 2015.Read the paper ↗PubMed ↗

One randomized crossover trial compared the two directly. Ten healthy women spent 45 minutes in an infrared sauna and 45 minutes cycling on separate days, and a day of rest served as the comparison. The sauna raised ear temperature more than cycling did, and cycling raised breathing rate more.5Source 5 · Crossover trialInfrared sauna as exercise-mimetic? Physiological responses to infrared sauna vs exercise in healthy women: A randomized controlled crossover trialHussain JN, Cohen MM, Mantri N, et al.. Complementary Therapies in Medicine, 2022.Read the paper ↗PubMed ↗ Neither session changed blood pressure or artery stiffness relative to the others, and the authors described the sauna's effects as thermoregulatory.

Over weeks, exercise did most of the work in the one trial that tested both. In eight weeks of supervised training in Jyväskylä, exercise raised estimated fitness by 6.2 mL/kg/min against no training, and 15 minutes of sauna after each session added another 2.7.6Source 6 · Randomized trialEffects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trialLee E, Kolunsarka I, Kostensalo J, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2022.Read the paper ↗PubMed ↗ In the Kuopio cohort, high measured fitness went with a 49% lower hazard of cardiovascular death and frequent sauna use with a 26% lower one. Men who had both did best.7Source 7 · Cohort studyJoint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort studyKunutsor SK, Khan H, Laukkanen T, et al.. Annals of Medicine, 2018.Read the paper ↗PubMed ↗