OBJECTIVE: Supervised exercise training (walking) is recommended in patients with intermittent claudication, both as a means to improve symptoms (walking distance and quality of life [QoL]) and as a means to improve general cardiovascular health (including vascular function and heart rate variability [HRV]). Our aim was to compare two types of supervised training (moderate-pain and pain-free walking) with comparable intensity based on heart rate, in terms of walking capacity, QoL, vascular function, biomarkers, and HRV in patients with intermittent claudication. METHODS: Thirty-six adults with intermittent claudication were randomized to either moderate-pain or pain-free exercise training (36 sessions, two or three times a week) or usual care (no supervised exercise). Initial walking distance and absolute walking distance using treadmill testing, flow-mediated vasodilation and pulse wave velocity using ultrasound, N-terminal pro-B-type natriuretic peptide and fibrinogen levels, HRV, and QoL (36-Item Short Form Health Survey questionnaire) were determined at baseline and after the intervention period. RESULTS: Twenty-nine patients (mean age, 64 ± 9 years; 72% male) completed the study. Both training programs similarly improved walking capacity. Initial walking distance and absolute walking distance significantly increased with either moderate-pain walking (median, 50 m to 107 m [P = .005] and 85 m to 194 m [P = .005], respectively) or pain-free walking (median, 53 m to 128 m [P = .003] and 92 m to 163 m [P = .003], respectively). QoL also similarly improved with both training modalities, whereas only moderate-pain walking was also associated with a statistically significant improvement in the vascular parameters flow-mediated vasodilation (4.4% to 8.0%; P = .002) and pulse wave velocity (6.6 m/s to 6.1 m/s; P = .013). Neither training program was associated with changes in biomarker levels and HRV. CONCLUSIONS: Both moderate-pain and pain-free training modalities were safe and similarly improved walking capacity and health-related QoL. Conversely, vascular function improvements were associated with only moderate-pain walking.