Effects of supervised treadmill-walking training on strength and endurance of the calf muscles of individuals with peripheral arterial disease

Objective: Supervised treadmill-walking training is an effective treatment to improve walking capacity for individuals with peripheral arterial disease (PAD). The primary aim of this study was to examine whether a supervised treadmill-walking program would improve calf-muscle strength and endurance in individuals with PAD. Design: The study included two stages. The first 12-week period was a nonexercise, within-subject control stage and the second 12-week period was an exercise training stage. Setting: Southern Cross University, Australia. Subjects: Twenty-two subjects with stable intermittent claudication were recruited. Their resting and postexercise ankle-to-brachial systolic blood pressure index (ABI) was 0.61 ± 0.13 and 0.41 ± 0.22, respectively. Interventions: Subjects trained in the laboratory, 3 sessions per week for 12 weeks. Outcome measurements: Walking capacity, calf-muscle strength (peak torques in isokinetic plantar flexion at velocities of 30 degrees per second, 60 degrees per second, and 90 degree per second) and endurance (mean peak force, total work, and mean power in repeated maximal plantar flexions at 60 degrees per second), ABI, and peak oxygen uptake were measured at the baseline and the end of each stage. Results: Analysis of variance (ANOVA) with repeated measures indicated that the supervised treadmill-walking program significantly increased calf-muscle strength and endurance. Walking capacity and peak oxygen uptake also showed significant improvements following the training program. Significant correlation was found between the improved calf-muscle endurance and walking capacity. Conclusion: Supervised treadmill exercise is highly effective in improving walking capacity. The improved walking capacity is accompanied by improved calf-muscle strength and endurance in individuals with PAD.