Many people enjoy soaking in a hot tub to relax, but they may not realize that their body is undergoing significant physiological changes. A recent study from the University of Oregon has explored how different heat sources--specifically hot tubs and saunas--affect our bodies in distinct ways.
While both sauna sessions and hot water immersion are popular for relaxation, the researchers sought to understand the underlying biological processes rather than simply asking participants which method they preferred. They focused on measuring internal responses related to thermoregulation, cardiovascular health, and immune system activity.
Investigating Heat Responses
The study involved 20 healthy volunteers, aged 20 to 28, who participated in controlled experiments at the Bowerman Sports Science Center. Each participant underwent ten sessions, experiencing three different heat therapies: immersion in a hot tub at 40.5°C (105°F) for 45 minutes, three 10-minute sessions in a traditional dry sauna at 80°C (176°F), and a 45-minute session in a far-infrared sauna, with temperatures ranging from 45 to 65°C (113-149°F).
Throughout these sessions, researchers monitored core body temperature, heart rate, blood pressure, and cardiac output, while also collecting blood samples to assess immune responses.
The findings indicated that all three methods raised body temperature, but immersion in hot water led to significantly higher core temperatures. Unlike the sauna, where sweat evaporates and cools the body, submersion in water prevents effective heat dissipation, causing the body to retain heat longer.
Unique Physiological Effects
This study highlighted that hot water immersion resulted in more pronounced cardiovascular responses, including increased heart rate and blood flow. Additionally, it was found that only hot water immersion triggered a notable rise in inflammatory cytokines and immune cell populations, indicating a unique stress response.
Jessica Atencio, the study's lead author, explained that the inability to sweat effectively while submerged leads to more significant changes in core temperature, creating a temporary inflammatory state. Such a response is similar to what occurs during exercise, suggesting that controlled heat exposure can be beneficial.
Broader Implications for Health
Understanding these differences is crucial, especially for individuals who may not be able to engage in traditional exercise due to various health issues. Passive heat therapies may serve as a viable alternative to enhance cardiovascular health and improve blood vessel function.
While this study focused on short-term responses in young, healthy individuals, it lays the groundwork for further research into the long-term health benefits of heat exposure. However, it is essential to note that heat therapy should not be seen as a replacement for physical activity, which remains the most effective strategy for cardiovascular health.
Before incorporating regular heat sessions into one's routine, especially for those with existing health conditions, medical consultation is highly recommended.
