A pilot study on the relationship between thermal habits, chronic inflammation, and arterial stiffness in young...

Atherosclerotic cardiovascular disease (ASCVD) progresses silently, highlighting the importance of early prevention. This pilot study aimed to examine the relationship between thermal habits-specifically hot-tub bathing-and biomarkers of chronic inflammation, as well as arterial stiffness in young adults.

Twenty-five participants were included: 9 males (mean age: 21.78 ± 2.05 years) and 16 females (mean age: 21.0 ± 0.97 years). We assessed hot bathing habits and measured plasma interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP), heat shock protein 70 (HSP70), and brachial-ankle pulse wave velocity (baPWV). IL-6 levels were significantly lower among habitual hot-tub bathers (p = 0.04 overall; p = 0.018 in females). In females, hsCRP tended to be lower with immersion bathing (p = 0.08). No significant differences were observed in hsCRP, HSP70, or baPWV in the overall, male, or female groups. In females, IL-6 negatively correlated with ABI (ρ = -0.543, p = 0.03), and baPWV negatively correlated with bathing duration (ρ = -0.562, p = 0.045). These findings suggest that habitual hot-tub bathing, a culturally embedded and easily implemented habit in Japan, may serve as a lifestyle intervention to reduce inflammation and support ASCVD prevention in young adults.