Heat therapy reduces sympathetic activity and improves cardiovascular risk profile in obese women with polycystic ovary syndrome.

Abstract

Polycystic Ovary Syndrome (PCOS) affects up to 15% of women and is associated with increased risk of obesity and cardiovascular disease. Repeated passive heat exposure (termed heat therapy ) is a lifestyle intervention with the potential to reduce cardiovascular risk in obesity and PCOS. Eighteen obese women with PCOS (Age: 27±4y, body mass index [BMI] 41.3±4.7 kg·m-2) were matched for age and BMI, then assigned to heat therapy (HT; n=9) or time control (CON; n=9). HT subjects underwent 30 one-hour hot tub sessions over 8-10 weeks, while CON subjects did not undergo heat therapy. Muscle sympathetic nerve activity (MSNA), blood pressure, cholesterol, C-reactive protein, and markers of vascular function were assessed at the start (Pre) and end (Post) of 8-10 weeks. These measures included carotid and femoral artery wall thickness and flow-mediated dilation (FMD), measured both before and after 20 min ischemia-20 min reperfusion (IR) stress. HT subjects exhibited reduced MSNA burst frequency (Pre:20±8, Post:13±5 bursts/min, p=0.012), systolic (Pre:124±5, Post:114±6 mmHg; p<0.001) and diastolic blood pressure (Pre:77±6, Post:68±3 mmHg; p<0.001), C-Reactive protein (Pre:19.4±13.7, Post:15.2±12.3 nmol/L; p=0.018), total cholesterol (Pre:5.4±1.1, Post: 5.0±0.8 mmol/L; p=0.028), carotid wall thickness (Pre:0.054±0.005 Post: 0.044±0.005 cm; p=0.010) and femoral wall thickness (Pre:0.056±0.009, Post:0.042±0.005 cm; p=0.003). FMD significantly improved in HT subjects over time following IR (Pre:5.6±2.5, Post:9.5±1.7%; p<0.001). No parameters changed over time in CON, and BMI did not change in either group. These findings indicate HT reduces sympathetic nerve activity, provides protection from IR stress, and substantially improves cardiovascular risk profiles in obese women with PCOS.