Effects of high intensity interval versus moderate continuous training on markers of ventilatory and cardiac efficiency in coronary heart disease patients

Abstract

Background: We tested the hypothesis that high intensity interval training (HIIT) would be more effective than moderate intensity continuous training (MIT) to improve newly emerged markers of cardiorespiratory fitness in coronary heart disease (CHD) patients, as the relationship between ventilation and carbon dioxide production (VE/VCO2 slope), oxygen uptake efficiency slope (OUES), and oxygen pulse (O2P).

Methods: Seventy-one patients with optimized treatment were randomly assigned into HIIT (n = 23, age = 56 ± 12 years), MIT (n = 24, age = 62 ± 12 years), or nonexercise control group (CG) (n = 24, age = 64 ± 12 years). MIT performed 30 min of continuous aerobic exercise at 70-75% of maximal heart rate (HRmax), and HIIT performed 30 min sessions split in 2 min alternate bouts at 60%/90% HRmax (3 times/week for 16 weeks).

Results: No differences among groups (before versus after) were found for VE/VCO2 slope or OUES (P > 0.05). After training the O2P slope increased in HIIT (22%, P < 0.05) but not in MIT (2%, P > 0.05), while decreased in CG (-20%, P < 0.05) becoming lower versus HIIT (P = 0.03).

Conclusion: HIIT was more effective than MIT for improving O2P slope in CHD patients, while VE/VCO2 slope and OUES were similarly improved by aerobic training regimens versus controls.

Figure 1

Experimental design.

Figure 2

The relative O₂ pulse curves as a function of percentage time during CPX, before and after intervention. (a) HIIT denotes high intensity interval training group. (b) MIT denotes moderate intensity training group. (c) CG denotes control group. ^* P < 0.05.