A 2022 study showed that sweating while exercising promoted the excretion of heavy metals. The sweat produced during exercising contained more heavy metals than that produced during low-temperature sauna use.

The study involved 12 young, healthy young adults. Researchers collected sweat samples from the participants after 20 minutes of either running on a treadmill or sitting in a sauna cabinet (at ~113°F). Then they measured concentrations of the heavy metals nickel, lead, copper, arsenic, and mercury in their sweat.

They found that engaging in exercise promoted higher concentrations of nickel, lead, copper, and arsenic in sweat, while sitting in a low temperature sauna did not produce such elevated levels. On the other hand, the sweating method did not affect sweat concentrations of mercury.

Heavy metals are naturally occurring metallic elements that are toxic or poisonous even at low concentrations. Exposures to heavy metals in everyday products such as arsenic in agricultural products, cadmium in cigarette smoke and automobile exhaust, lead in toys, and mercury in dental amalgam and certain types of fish, are common occurrences.

These findings suggest that sweating through exercising facilitates heavy metal excretion from the body more effectively than a very low temperature sauna. This was a very small study, however, and larger studies are needed to confirm these findings.

It’s noteworthy that these findings don’t undermine the utility of sauna use to promote heavy metal excretion in sweat. The average person loses 0.6 to 1.0 kilograms of sweat per hour in a typical traditional sauna session, which is typically considerably hotter (158°F to 212°F) than the experimental conditions used in this study. Consequently, sauna use likely induces considerably greater sweat losses than exercise, depending on the conditions and duration.

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