Acute and chronic effects of lower leg heat therapy on blood pressure in older hypertensive women

Introduction: Hypertension affects ~50% of U.S. adults, with <25% being well-managed. Older women have particularly poor hypertension control rates, despite conventional lifestyle and drug treatments. Alternatives, such as heat therapy, are promising adjuvant treatment that may reduce blood pressure (BP) and cardiovascular disease risk. This study tested the hypothesis that 8-weeks of home-based, lower-leg heating would reduce BP both acutely (i.e., average change per session) and chronically (i.e., change from pre- to post-intervention) in older women with hypertension. Methods: Fifty-five older women with hypertension were randomized to either a heat therapy (INT, water temperature 42°C; n=27, 69±5y [mean±SD]) or a thermoneutral control (CON, 35°C; n=28, 69±5y) group. Participants completed 8-weeks of at-home sessions (~4/week; 45 min/session) immersing their legs ~33 cm in a commercially available portable spa bath in a seated position. Acute changes (Δ) in BP were assessed using the mean difference between oscillometric systolic and diastolic BP immediately before and after each heating over the 8-week intervention. Chronic ΔBP was determined using the awake period mean of 24-h ambulatory BP monitoring measured pre- (PRE) and post- (POST) intervention. Heart rate (HR) was taken from the corresponding BP measuring device. Results: Pre-intervention ambulatory awake systolic BP (INT: 140±6 vs. CON: 142±7 mmHg; p=0.476) and diastolic BP (80±6 vs. 79±6 mmHg; p = 0.482) were not different between groups. Women in INT had greater acute decrease in systolic (Δ-7±6 vs. Δ-2±4mmHg; p=0.002) and diastolic BP (Δ-5±3 vs. Δ-2±2mmHg; p<0.001), with higher HR (Δ5±4 vs. Δ-3±3BPM; p<0.001) compared to CON. However, when assessing the chronic changes, systolic BP (Δ2±8 vs. Δ0±9mmHg; p=0.430), diastolic BP (Δ0±5 vs. Δ1±5mmHg; p=0.568), and HR (Δ-2±5 vs. Δ1±6BPM; p=0.081) were not different between groups. No correlations were found between the acute and chronic Δsystolic BP (R=0.037; p=0.784) or Δdiastolic BP (R=0.071; p=0.605). Conclusions: Our data demonstrated that 8-weeks of lower-leg heat therapy consistently induced acute systolic and diastolic BP reductions in older women with hypertension. However, these acute reductions did not translate to chronic BP reductions in this patient population. Accordingly, this disconnect between the acute and chronic responses warrants further research to better identify the heating regimen (e.g., frequency and duration) or strategy that produces chronic BP improvements. Supported by the National Institutes of Health (R01AG059314 and F32HL167556) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.