Abstract Body (Do not enter title and authors here): Background: Patients with peripheral artery disease (PAD) experience leg muscle pain that limits walking and the ability to adhere to exercise therapy. Neuromuscular electrical stimulation (NMES) induces exercise-like muscle contractions and can be performed without pain. Hypothesis and Purpose: We hypothesised that a 12-week program of NMES would improve walking capacity compared with placebo-control in patients with PAD.
Study Design and Methods: Single-centre, parallel-group, double-blinded, randomized placebo-controlled trial. Participants were randomized to a 12-week program of NMES or sham placebo-control (CON). This was followed by a 6-week off-intervention follow-up. Outcomes were assessed at baseline (week 0), midway (week 6) and at the end of the intervention period (week 12), and again at the end of the follow-up phase (week 18). Sample Size: 180 patients (n=90 per group) from public hospital, private hospital and community clinic recruitment sites. Population Studied: Adults (mean age: 72 ± 9 y; ABI: 0.69 ± 0.20) with a diagnosis of PAD who experience leg pain when walking (intermittent claudication). Interventions: Participants used a footplate-NMES device (Revitive Medic Coach) for 2x30 min periods each day to deliver stimulation sufficient to induce contraction of the leg muscles. Control participants used a sham device that delivers a low intensity stimulation that does not induce muscle contraction. Primary End Point: Maximum distance during the six-minute walk test (6MWT) at week 12. Secondary End Points: Pain-free distance during the 6MWT, maximum and pain-free walking time during a graded treadmill test, self-reported walking impairment questionnaire (WIQ), disease-specific QOL assessed using the intermittent claudication questionnaire (ICQ), and accelerometer derived physical activity levels. Power Calculation: At an alpha-level of 0.05 and a power of 0.80 the trial was powered to detect a 30 m change (effect size 0.33) in 6MWT distance in the NMES group compared with CON.
Outcomes: There was no difference in 6MWT distance between groups at week 12 (marginal mean difference (MMD): 3.68 m; 95% CI: -4.21 to 11.56; P = 0.361). At week 18, six weeks after the intervention ceased, 6MWT distance was greater in the NMES group compared with CON (MMD: 10.77 m; 95% CI: 2.82 to 18.72; P = 0.008). Pain-free 6MWT distance increased and was greater in the NMES group compared with CON at week 12 (MMD: 23.08 m; 95% CI: 6.55 to 39.61; P = 0.024).