About this trial
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. Compared to SET, home-based exercise is more accessible and less burdensome. Yet, evidence-based guidelines recommend SET over home-based exercise for PAD. Walking exercise is first line therapy to improve walking distance for PAD, but it does not eliminate ischemic leg symptoms in most people with PAD. 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. 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. 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.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
An ABI <= 0.90 at baseline.
Vascular lab evidence of PAD (such as a toe brachial pressure less than or equal to 0.70 or an ankle brachial index less than or equal to 0.90), or angiographic evidence of PAD defined as at least 70% stenosis of an artery supplying the lower extremities.
An ABI of >0.90 and <1.00 who experience a 20% or greater drop in ABI in either leg after the heel-rise test.
Disqualifiers
Above- or below-knee amputation
Limb-threatening ischemia defined as an ABI <0.40 with symptoms of rest pain
Wheelchair confinement or requiring a walker to ambulate
Walking is limited by a condition other than PAD
Trial design
Factorial
Treatments tested in this trial
Supervised Treadmill Exercise
BehavioralThis is a 12 week intervention where participants will walk for exercise 3 times a week on a treadmill at a center while being supervised by healthcare personnel.
Home-Based Exercise
BehavioralThis is a 12 week intervention where participants will walk at home for exercise with guidance from a study coach. They will have 4 in person visits in the first four weeks and then have weekly phone calls in the last 8 weeks of the intervention with their coach.
Nitrate-rich beetroot Juice
Dietary supplementParticipants will drink one shot of nitrate rich beet-root juice twice daily for 12 weeks.
Treatment groups
Trial outcomes
Primary outcomes
Six-Minute Walk Distance
Change in six-minute walk distance
Secondary outcomes
Walking Impairment Questionnaire (WIQ) Distance Score
WIQ distance score - Range 0-100, 100 is best.
PROMIS Mobility Questionnaire Score
PROMIS mobility score from administered PROMIS questionnaire. Score range is from zero to infinity and a higher score means a better outcome.
20-meter Improvement in Six-Minute Walk Distance
Meaningful response to exercise interventions
Step Count
Step count measured over seven days with the FITBIT
Other outcomes
Physical Activity Step Count
Step count measured over seven days with FITBIT
Physical activity distance
Physical activity distance measured over seven days with FITBIT
Short physical performance battery (SPPB)
SPPB range, range 0-12, 12-best
Walking Impairment Questionnaire (WIQ) Stair Climbing Score
WIQ stair climbing score from administered WIQ, range 0-100, 100 is best.
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