PURPOSE: There is a lack of knowledge as to how different exercise-based cardiac rehabilitation programming affects skeletal muscle adaptations in coronary artery disease (CAD) patients. We first characterized the skeletal muscle from adults with CAD compared with a group of age- and sex-matched healthy adults. We then determined the effects of a traditional moderate-intensity continuous exercise program (TRAD) or a stair climbing-based high-intensity interval training program (STAIR) on skeletal muscle metabolism in CAD. METHODS: Sixteen adults (n = 16, 61 +/- 7 yr), who had undergone recent treatment for CAD, were randomized to perform (3 d/wk) either TRAD (n = 7, 30 min at 60% to 80% of peak heart rate) or STAIR (n = 9, 3x6 flights) for 12 wk. Muscle biopsies were collected at baseline in both CAD and healthy controls (n = 9), and at 4 and 12 wk after exercise training in CAD patients undertaking TRAD or STAIR. RESULTS: We found that CAD had a lower capillary-to-fiber ratio (C/Fi; 35% +/- 25%, p = 0.06) and capillary-to-fiber perimeter exchange (CFPE) index (23% +/- 29%, p = 0.034) in type II fibers compared with healthy controls. However, 12 wk of cardiac rehabilitation with either TRAD or STAIR increased C/Fi (type II 23% +/- 14%, p < 0.001) and CFPE (type I 10% +/- 23%, p < 0.01; type II 18% +/- 22%, p = 0.002). CONCLUSION: Cardiac rehabilitation via TRAD or STAIR exercise training improved the compromised skeletal muscle microvascular phenotype observed in CAD patients.

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