Lower extremity peripheral artery disease (PAD) affects more than 200 million people worldwide. PAD is characterized by atherosclerotic lumen narrowing or occlusion of the lower limb arteries, leading to an imbalance between oxygen supply and demand downstream, especially in activated muscle during exertion. The hallmark symptom of PAD is typical intermittent claudication, defined as reproducible exertion-induced cramping or pain in the lower extremities, which is rapidly relieved with rest.~Patients with symptomatic PAD avoid exertion and tend to have muscle weakness, an altered gait and lower limb biomechanics. This results in impaired walking performance, accelerated functional decline, and reduced quality of life.~Supervised exercise training (SET) is considered among first-line therapies for patients with symptomatic PAD, combined with general cardiovascular risk management, lifestyle adaptation and pharmacological treatment. The clinical benefits of SET for patients with PAD are well established, with improved walking capacity and an improved quality of life as the primary outcomes.~Although without clear consistency, the guidelines give recommendations in terms of claudication pain severity, SET volume, duration, and frequency. However, no or little guidance is offered as far as training intensity is concerned. Most of the previous studies on SET, in the context of PAD, did not distinguish between symptom intensity and common training intensity measures such as % of maximal heart rate (%HRmax), % of HR reserve (%HRR), % of peak oxygen uptake (%VO2peak), % of VO2 reserve (%VO2R), or the rate of perceived exertion (RPE).~A meta-analysis by Parmenter et al. showed that vigorous (%HRpeak: 77-96, %VO2peak: 64-90, RPE: 14-17) exercise training improved cardiorespiratory fitness (VO2peak) more than light- to-moderate exercise therapy intensity in patients with PAD, but the changes in walking performance in these patients remain to be determined. In a recent meta-analysis, we demonstrated that both training modality and exercise intensity (based on %peak heart rate, %peak oxygen uptake, or the rate of perceived exertion) should be considered when looking for the best results in patients with symptomatic PAD. More precisely, we showed that, when training modalities were considered, walking at vigorous intensity showed the greatest improvement in maximal walking distance (MWD), while walking at light-to-moderate intensity showed the greatest improvement in pain-free walking distance. We also showed that vigorous was superior to light-to-moderate exercise intensity in improving cardiorespiratory fitness; and that, when training modalities were considered, cycling and other non-walking forms of training performed at vigorous intensity elicited the greatest improvements in cardiorespiratory fitness.~The results of our meta-analysis call for study of the individual roles of each exercise intensity and modality on walking performance and cardiorespiratory fitness in patients with symptomatic PAD.~High-intensity interval training (HIIT) is composed of brief bursts of vigorous intensity interspersed with periods of rest or low-intensity exercise. HIIT may be better than moderate-intensity training (MIT) in improving cardiorespiratory fitness and functional capacity in patients with cardiovascular and metabolic diseases, but in patients with symptomatic PAD, the effects of such modalities on walking ability and cardiorespiratory fitness remain to be clearly determined.~The primary objective of this study is to compare the effects of 12-week-long exercise training (short-duration high-intensity intervals vs. low-to-moderate intensity) on treadmill performance in patients with symptomatic PAD.~It is hypothesized that treadmill performance would be improved to a greater extent after high-intensity exercise training
Supervised exercise training (SET) is considered among first-line therapies for patients with symptomatic lower extremity peripheral artery disease (PAD), combined with general cardiovascular risk management, lifestyle adaptation and pharmacological treatment.~Although without clear consistency, the guidelines give recommendations in terms of claudication pain severity, SET volume, duration, and frequency. However, no or little guidance is offered as far as training intensity is concerned. Most of the previous studies on SET, in the context of PAD, did not distinguish between symptom intensity and common training intensity measures such as % of maximal heart rate (%HRmax), % of HR reserve (%HRR), % of peak oxygen uptake (%VO2peak), % of VO2 reserve (%VO2R), or the rate of perceived exertion (RPE).~In a recent meta-analysis, we demonstrated that both training modality and exercise intensity (based on %peak heart rate, %peak oxygen uptake, or the rate of perceived exertion) should be considered when looking for the best results in patients with symptomatic PAD. These results call for study of the individual roles of each exercise intensity and modality on walking performance and cardiorespiratory fitness in patients with symptomatic PAD.~High-intensity interval training (HIIT) is composed of brief bursts of vigorous intensity interspersed with periods of rest or low-intensity exercise. HIIT may be better than moderate-intensity training (MIT) in improving cardiorespiratory fitness and functional capacity in patients with cardiovascular and metabolic diseases, but in patients with symptomatic PAD, the effects of such modalities on walking ability and cardiorespiratory fitness remain to be clearly determined.~The primary objective of this study is to compare the effects of 12-week-long exercise training (short-duration high-intensity intervals vs. low-to-moderate intensity) on treadmill performance in patients with symptomatic PAD.~It is hypothesized that treadmill performance would be improved to a greater extent after high-intensity exercise training