Feasibility of unsupervised, home-based leg heat therapy in older adults: a pilot, sham-controlled trial

Heat therapy (HT) using sauna or hot water immersion can improve cardiovascular and physical function, but these approaches are often impractical for older adults. This pilot, randomized, sham-controlled trial evaluated the feasibility of unsupervised, home-based leg HT using water-circulating trousers in sedentary older adults. Twenty-four participants (mean age: 70 ± 3 yr; 15 women) were randomized to HT (42°C) or sham (33°C) for 90 min daily over 12 wk. Feasibility outcomes included adherence, retention, and safety. Secondary outcomes included 6-min walk distance, sit-to-stand time, plantar flexor strength, MRI-derived muscle morphology, quality of life, and blood pressure. Four participants (two per group) withdrew early due to health status changes or scheduling conflicts. Among those who completed the study, adherence was high (HT: 93 ± 11% and sham: 92 ± 35%). Four HT participants reported minor thermal injuries at the knees, which did not hinder adherence or study participation. There were no significant differences between groups for the secondary outcomes. At 12 wk, the HT group increased their 6-min walk distance by 37.6 m (95% CI: 14.3 to 60.8), compared with 11.5 m (-12.2 to 35.1) in the sham group (group-by-time interaction, P = 0.092). Plantar flexor strength rose by 4.3 N·m (-2.0 to 10.6) in the HT group and declined by 2.6 N·m (-16.1 to 10.9) in the sham group, with no significant group-by-time interaction (P = 0.31). These findings support the feasibility and acceptability of home-based leg HT in older adults and indicate that protocol and device refinements-particularly to improve usability and safety-are needed before advancing to a larger efficacy trial.NEW & NOTEWORTHY This pilot trial demonstrates the feasibility of unsupervised, home-based leg heat therapy using water-circulating trousers in older adults. High adherence, minimal adverse events, and promising improvements in walking endurance support its potential as a scalable intervention for mobility preservation in aging. Findings highlight key considerations for future efficacy trials, including device refinements to enhance safety and usability.