Home-based lower leg heat therapy in postmenopausal women with hypertension. I. Effects on blood pressure

Despite conventional drug treatment for hypertension, postmenopausal women in the United States maintain relatively poor blood pressure (BP) control rates. Alternatives, such as heat therapy, represent promising adjuvant treatments that may reduce BP. This study tested the hypothesis that 8 wk of home-based, lower leg heating would induce acute BP reductions that may contribute to sustained BP lowering in postmenopausal women with hypertension. Fifty-nine participants completed a randomized trial to receive either a thermoneutral sham (i.e., sham; 35°C; n = 30, 69 ± 5 yr) or heat therapy (42°C; n = 29, 69 ± 5 yr). Participants completed 8 wk of home-based, lower leg water immersion (≈4 sessions/wk; 45 min/session). Acute BP responses were assessed pre-to-postimmersion, whereas pre-to-postintervention BPs were assessed using 24-h ambulatory monitoring. The average acute reductions in BP and increases in heart rate pre-to-postimmersion were greater in heat therapy (sham, systolic: -2 ± 4 mmHg, diastolic: -2 ± 2 mmHg, heart rate: -3 ± 3 beats/min; heat therapy, systolic: -6 ± 6 mmHg, diastolic: -5 ± 3 mmHg, heart rate: 5 ± 4 beats/min; all P < 0.01). However, these acute responses did not translate into significant reductions in ambulatory BP, whereby ΔBP did not differ between groups (sham, systolic: 0 ± 8 mmHg, diastolic: 1 ± 5 mmHg; heat therapy, systolic: 2 ± 8 mmHg, diastolic: 1 ± 5 mmHg; all P ≥ 0.412). Our data demonstrate that 8 wk of home-based lower leg heat therapy reduces BP acutely, but was not associated with a chronic BP-lowering effect in postmenopausal women with hypertension. Therefore, these findings suggest that home-based, lower leg heat therapy is insufficient to elicit sustained BP reductions, despite consistent acute BP reductions, in postmenopausal women with either treated or untreated hypertension.NEW & NOTEWORTHY This study hypothesized that 8-wk of home-based lower leg heat therapy would reduce blood pressure from pre-to-postimmersion (i.e., acute) and pre-to-postintervention (i.e., chronic) in postmenopausal women with hypertension. Although this paradigm consistently reduced blood pressure acutely, there was no chronic blood pressure lowering effect. These findings highlight the need to better understand the appropriate frequency, temperature, duration, and modality of heat therapy and how certain conditions, like hypertension, modulate physiological adaptations.