BYU Tests Daily Sauna During a Week at 1,000 Steps a Day

Brigham Young University researchers are recruiting healthy adults to test whether daily Finnish dry sauna sessions can help preserve blood vessel function, muscle health and exercise capacity during a week of sharply reduced activity.

The randomized trial, HEAT-RPA, plans to enroll 60 people in Provo, Utah. Two groups will cut their walking to roughly 1,000 steps a day for seven days, using a power wheelchair to limit walking while continuing daily activities. One will receive sauna heat; the other will sit in the same environment at room temperature. A third group will keep its usual activity and use the sauna.

The trial’s registration was first posted September 29; it lists January 1, 2026, as the actual study start. The trial is recruiting, and no results have been posted. Its question is whether heat can lessen the physiological losses that accompany a temporary drop in movement, a situation the researchers connect to illness, injury and hospitalization.

Seven days, three groups

Participants will be assigned to one of three groups:

• Usual activity plus sauna: maintain habitual activity and complete one supervised Finnish dry sauna session each day.
• Reduced activity without heat: limit walking to about 1,000 steps daily and attend a room-temperature sauna session each day.
• Reduced activity plus sauna: follow the same step limit and complete one supervised dry sauna session daily.

The comparison between the two reduced-activity groups will test the effect of adding heat under the same movement restriction. The room-temperature visits also account for time spent attending the sessions. Participants and the staff administering them will know which treatment is being used; the registry lists outcome-assessor masking and says coded outcome analysis will be used when feasible.

What the researchers will measure

The registered primary outcomes include blood vessel function in the leg, maximum power during a knee-extension cycling test, whole-body lean mass and the rate at which skeletal muscle builds new protein.

Ultrasound will track blood flow through the femoral artery during passive leg movement. A progressively harder cycling test will measure exercise power. Body-composition scans will measure lean mass, while muscle biopsies and a labeling technique will assess protein synthesis.

Secondary measures include leg lean mass, glucose readings from a continuous monitor, daily step counts and core-temperature responses to sauna. Most primary assessments are scheduled four days before the intervention and one day after the final sauna visit.

From targeted muscle heat to a whole sauna

The study builds on earlier BYU experiments using pulsed shortwave diathermy, a device that heats tissue locally. A 2019 study of 23 healthy volunteers found that two hours of targeted heat daily during 10 days of limb immobilization reduced muscle atrophy and helped preserve mitochondrial function. A 2021 trial of 21 volunteers found that daily localized heating also reduced the decline in leg vascular function during immobilization.

HEAT-RPA tests whether a Finnish dry sauna can produce protection during a broader reduction in everyday activity. The earlier findings establish a reason to investigate; they do not establish the outcome of this sauna trial.

The details that will matter when results arrive

The public registration specifies daily supervised dry sauna but does not give a temperature or session duration. Those details will matter for readers comparing the findings with their own sauna use. The Sauna Research Foundation’s effort to standardize heat-therapy reporting addresses exactly this problem: studies need to describe the exposure well enough for others to understand what was tested.

The type of heat matters, too. This trial uses Finnish dry sauna. It does not test infrared sauna or hot-water immersion, distinctions explored in our coverage of infrared and traditional sauna research.

Eligibility is limited to healthy men and premenopausal women aged 18 or older who meet the study’s screening requirements. People with cardiovascular or metabolic disease, a history of heat-related illness, or regular recent sauna or hot-tub use are excluded. Even a positive result would need further testing before it could establish benefits for patients recovering from illness or surgery.

The registry lists January 2027 as the estimated primary completion and May 2027 as the estimated study completion. Neither date guarantees a publication. For now, the study offers a clearly defined test of whether daily sauna can help during a short period of reduced mobility, with the answer still to come.