The objective of this study is to evaluate the benefits of participating for 8 weeks in a home-based daily treatment with heat therapy (HT) or a thermoneutral control intervention, as assessed by vascular function, walking tolerance and quality of life.

Heat therapy (HT) is an emerging non-invasive approach that has been shown to enhance vascular function of the leg in old individuals. The objective of this randomized, controlled study is to evaluate the benefits of participating for 8 weeks in a home-based daily treatment with heat therapy (HT) or a thermoneutral control intervention, as assessed by vascular function, walking tolerance and quality of life. The central hypothesis of this study, based on preliminary data, is that exposure to HT will enhance the oxygenation of calf muscles during exercise and as a result, the onset of pain will be delayed and walking performance will be enhanced. The duration (8 weeks) was chosen based on the recent report of Brunt and co-workers that the improvement in endothelial function promoted by repeat HT in sedentary individuals peaks at 8 weeks following the onset of treatment. Heat Therapy will be applied daily for 90 minutes using water-circulating 'pants' connected to a water pump. Outcomes will be assessed at the halfway point (end of week 4), at the completion of the intervention (end of week 8) and 4 weeks after the end of the intervention (week 12).

Inclusion Criteria:

• Men and women with a stable symptomatic PAD for ≥6 months
• Ankle brachial index <0.9 in at least one leg
• Age between 40 and 80 years

Exclusion Criteria:

• Uncontrolled Diabetes (HbA1C > 8.5 measured within 3 months prior to date of consent)
• Wheelchair bound
• Use of a walking aid (i.e. cane, crutches, walker, motorized chair)
• Critical limb ischemia (ischemic rest pain or ischemia-related non healing wounds or tissue loss
• Impaired thermal sensation in the legs
• Exercise-limiting comorbidity
• Chronic Heart Failure stages C and stage D (Stage C: structural heart disease is present and symptoms have occurred; Stage D: presence of advanced heart disease with continued heart failure symptoms requiring aggressive medical therapy)
• Morbid obesity BMI > 35 or unable to fit into water-circulating pants
• Open wounds or ulcers on the extremity
• Prior amputation
• Lower extremity revascularization, major orthopedic surgery, cardiovascular event, or coronary revascularization in the previous three months
• Planned revascularization or major surgery during the next six months
• Plans to change medical therapy during the duration of the study
• Active treatment for cancer
• Chronic kidney disease (eGFR <30 by MDRD or Mayo or Cockcroft-Gault formula).
• HIV positive, active HBV or HCV disease.
• Presence of any clinical condition that makes the patient not suitable to participate in the trial.
• Unable to walk on the treadmill

Baseline characteristics of participants with PAD that completed the 8-wk intervention.

Throughout the duration of the study (i.e. approximately 12 weeks).

Participants were informed that there were two different categories of heat therapy, "low heat" and "high heat," and that both might be beneficial for claudication symptoms.