Pelagia Koufaki , Thomas H. Mercer, Keith P. George, James Nolan
School of Health Sciences, Queen Margaret University, EH21 6UU Edinburgh, United Kingdom. E-mail: pkoufaki@qmu.ac.uk
DOI: 10.2340/16501977-1278

Objectives: The health benefits of high-intensity interval training in cardiac rehabilitation warrant further research. We compared the effectiveness of low-volume high-intensity interval training vs continuous aerobic exercise training in chronic heart failure.
Design/Settings: Unblinded, two arm parallel design with random assignment to exercise interventions in out-patient hospital rehabilitation gym.
Methods: Patients with signs of chronic heart failure and ejection fraction < 45%, (mean age: 59. 1 years (standard deviation (SD) 8. 6); 3 women) completed 6 months of exercise using continuous aerobic exercise training (n = 9) or high-intensity interval training (n = 8). Cardiorespiratory fitness was determined during cycle ergometry using respiratory gas exchange analysis. Functional capacity was assessed via sit-to-stand and gait speed. Quality of life was assessed using the MOS Short-Form 36 and Minnesota living with heart failure questionnaires. Cardiac autonomic regulation was assessed using Heart Rate Variability.
Results: Analysis of Covariance revealed significant time effects but no group × time interactions for exercise and functional capacity outcomes. Peak oxygen uptake (VO2peak) improved by a mean of 14. 9% (SD 16. 3%) from baseline and by 22% (SD 28. 3) at ventilatory threshold in both groups. Sit-to-stand (11. 9 (SD 11%)) and gait speed (16. 0 (SD 19%)) improved similarly in both groups. No changes in quality of life or heart rate variability were noted. Training adaptations in high-intensity interval training were achieved despite a significantly reduced time commitment and total work volume compared to continuous aerobic exercise training.
Conclusion: Low-volume high-intensity interval training is a feasible and well tolerated training modality in cardiac rehabilitation settings, but is not more effective than continuous aerobic exercise training.