Heat therapy has been used for ages to promote aspects of health, such as calming seizures in the fifth century and treating psychiatric disorders in the 19th century. However, technological advancements in the modern era have enabled scientists to examine the specific benefits of the therapy and factors underlying it more fully.

Recent research suggests that various forms of passive heat can produce effects similar to those of exercise. Although the benefits of exercise surpass those of passive heat, the therapy may be a helpful addition to a fitness regimen for some people.

Passive heat can improve a broad range of health conditions.

Effects Similar to Mild-to-Moderate Exercise

A clinical trial from the University of Oregon, published in the American Journal of Physiology, investigated the effects of hot baths and saunas. The participants were assigned to one of three groups: hot water immersion, traditional sauna, or far infrared sauna.

The authors determined heat-induced sweat loss by measuring body weight before and after each session of passive heat. They assessed effects on the cardiovascular system and immunity by testing blood samples and measuring heart rate, blood pressure, and heart output.

“Our research, and that of others, are showing that both hot tubs and saunas, when done correctly and consistently, are associated with improved health,” corresponding author Christopher Minson of the Bowerman Sports Science Center at the University of Oregon, told The Epoch Times in an email.

“Part of this response is because when our body temperature is elevated for a period of time, it produces effects in heart rate, sweating, and the distribution of blood throughout the body that are similar effects of those of mild-to-moderate exercise.”

How Passive Heat Is Like Exercise

Passive heat produces a rise in skin and body core temperatures, which triggers sweating and dilation of blood vessels in the skin to cool the body, the clinical trial authors stated. To offset the widespread dilation of vessels in the skin, the heart’s output can increase to double its resting output. These heat-regulatory mechanisms and cardiovascular responses are similar to what happens during moderate aerobic exercise.

Passive heat stress has effects on the immune system that resemble those in exercise. Each session of exercise causes a temporary increase in inflammation that triggers the body’s anti-inflammatory response. This reduces chronic low-level inflammation and leads to beneficial effects on heart and metabolic health.

“We always say that exercise is the primary nonpharmacological treatment that people should be doing to promote health, but some people can’t or just won’t exercise,” study lead author Jessica Atencio, a doctoral student in the lab of Christopher Minson, said in a statement. “Heat therapy is good supplementation.”

Types of Passive Heat

Hot tubs and different types of saunas offer a variety of choices for heat therapy.

Benefits of Passive Heat

Passive heat therapy produces a range of health benefits.

Extends Years of Good Health

Health span denotes the part of life when a person experiences optimal health with only minimal physical or mental limitations. Consequently, it permits the enjoyment of a high quality of life without the burden of chronic illnesses or disabilities.

A comprehensive review published in Temperature: Multidisciplinary Biomedical Journal examined research to date on passive heat. It found evidence that dry saunas may offer multiple wellness benefits that include reducing blood pressure and relieving symptoms of chronic obstructive pulmonary disease, mild depression, fibromyalgia, and chronic fatigue. Hydrotherapy, such as steam baths, can help manage symptoms of heart failure, heart attack, asthma, obesity, arthritis, and anxiety. Finnish saunas may reduce the risk of cardiovascular disease—including stroke, high blood pressure, and sudden heart death—as well as psychotic disorders, lung disease, and death from all causes.

According to the authors, the beneficial effects of passive heat may be associated with its antioxidant, cell-protective, and anti-inflammatory properties. The therapy’s synergistic effects on immune function, cardiovascular, neuroendocrine, and circulatory functions may also play a role.

Helps Protect the Brain

A review published in Frontiers in Physiology indicates that passive heat may offer a significant benefit to people with neurodegenerative conditions, which are associated with misfolding and aggregation of damaged proteins in the brain. The authors found that passive heat can increase the expression of heat shock proteins, substances that reduce or prevent the toxic effects of protein aggregation and improve neuromuscular function. Heat therapy may also improve cerebral blood flow, muscle function, and markers of metabolic health. It’s possible that all the above effects could slow the progression of Alzheimer’s disease and Parkinson’s disease.

Improves Exercise Performance

Athletes engage in warm-up before exercise because it has been suggested that an increase in muscle and core temperature is important in task readiness. However, a lengthy transition period between a warm-up and exercise session causes a decrease in muscle and core body temperature, which reduces performance.

A systematic review and meta-analysis evaluated seven clinical trials that tested the effects of passive heat during the transition period between a warm-up and an exercise session. The results indicated that using a heated garment during this time significantly reduced the decline in muscle temperature and enhanced peak power output in exercise. The heated garment produced a favorable but not significant decline in core temperature. More research is needed in this area to ascertain the benefits.

Precautions and How-Tos

Engaging in any type of passive heat is not recommended for everyone, so it is important for people to check with their doctors before trying it, Dr. Elizabeth Ranft, a family medicine physician, told The Epoch Times in an email. Also, if they feel any kind of distress during a session, they should stop and not engage in it again until consulting with their physicians.

She warned that passive heat can potentially be harmful for those with:

• Unstable coronary artery disease


• A recent heart attack


• Uncontrolled high blood pressure


• Severe heart valve disease


• An active infection, fever, or hives


• Orthostatic hypotension, which is low blood pressure that occurs when standing after sitting or lying down

Anyone should refrain from alcohol consumption during a passive heat session, as the combination can lower blood pressure and cause heart complications, according to Ranft.

To initiate a passive heat program, she recommends sitting in a Finnish sauna for 10 minutes and gradually increasing the session time by five minutes until reaching 20 to 30 minutes. While Finnish saunas typically have low humidity, sessions can be interspersed with brief periods of higher humidity by throwing water over the rocks. Most studies recommend four to seven sessions a week, she said.

“As always, exercise will provide the best benefits over any form of heat therapy,” Ranft said. “However, for those individuals who cannot exercise or who want to supplement their exercise routine, heat therapy is a great option with proven health benefits.”