SMART Exercise for PAD

Supervised exercise therapy (SET), consisting of treadmill exercise conducted three times weekly at a center while supervised by healthcare personnel, is first line therapy for people disabled by lower extremity peripheral artery disease (PAD). However, travelling three times/week to a center for SET is burdensome. As of 2018, only 1.3% of patients with Medicare and symptomatic PAD had enrolled in SET. Compared to SET, home-based exercise is more accessible and less burdensome. Yet, evidence-based guidelines recommend SET over home-based exercise for PAD. In 2021, the investigators reported that a home-based exercise intervention that incorporated behavioral methods significantly improved six-minute walk in PAD, compared to an attention control group. But no randomized trials have compared SET to a home-based exercise intervention that incorporated behavioral change methods in PAD. However, 45% of people with PAD do not meaningfully respond to exercise interventions, defined as failure to improve six-minute walk by \> 20 meters. This phenomenon occurs for both supervised and home-based exercise. The investigators' work and that of others showed that nitrate-rich beetroot juice, which increases plasma nitrite, limb perfusion, and skeletal muscle function, significantly improved exercise tolerance and reduced non-response to exercise in people with and without PAD. Therefore, the investigators will use a 2 x 2 factorial design to address two major barriers to achieving benefits from exercise therapy for PAD: First, guideline recommendations for supervised exercise therapy (SET) as first line therapy for PAD. Second, the inability of exercise therapy to eliminate PAD-related disability in most people with PAD. In this 2 x 2 factorial design, participants will be randomized to one of four groups for 12 weeks: Supervised treadmill exercise + nitrate rich beetroot juice; supervised treadmill exercise + placebo, home-based walking exercise + nitrate rich beetroot juice, home-based walking exercise + placebo.