Introduction: We previously reported that arm ergometer exercise training improves walking distance in patients with claudication similar to treadmill exercise training through unknown mechanisms. This is the first study to investigate the effects of 12 weeks of arm ergometer or treadmill training on cardiorespiratory functions during treadmill exercise testing in patients with claudication, as compared to a usual care control group. Hypothesis: Both arm ergometer and treadmill training will significantly improve cardiorespiratory functions, which will contribute to improvement in both pain-free walking distance (PFWD) and maximal walking distance (MWD). Methods: Participants (21m, 7f, mean age 65.6 yrs, 86 % smoke hx., 27% diabetes) with claudication were randomly assigned to supervised exercise training [arm ergometry (n=10) or treadmill (n=10) ] for 12 weeks, 3h/week, or to a usual care control group (n=8). Double product at stage 1 and at MWD, anaerobic threshold, and VO 2 at onset of claudication pain and VO 2 peak were assessed during a symptom-limited, graded treadmill exercise test. Changes in these functions from baseline were analyzed between groups via ANCOVA and associations between variables were determined by Pearson’s partial correlations. Results: Groups did not differ in baseline demographic, medical or exercise variables. There were significant differences in response of cardiorespiratory variables to training in both exercise groups compared to the control group, but no statistical differences between exercise groups. Significant moderate correlations were found between changes in all cardiorespiratory variables and changes in PFWD or MWD (Table 1 ). Conclusion: Improvements in cardiorespiratory functions following arm ergometer or treadmill training were significantly associated with changes in PFWD and MWD, supporting systemic contributions to exercise training-related improvements seen in patients with claudication. Changes from Baseline in Submaximal and Maximal Cardiorespiratory Variables and Walking Improvement