Both Traditional and Stair Climbing-based HIIT Cardiac Rehabilitation Induce Beneficial Muscle Adaptations

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 center dot wk(-1)) either TRAD (n = 7, 30 min at 60%-80% of peak heart rate) or STAIR (n = 9, 3 x 6 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.