High-intensity interval training for health benefits and care of cardiac diseases - The key to an efficient exercise protocol

Table 2 Mode, intensity, and VO_2peak increment in high-intensity interval training versus moderate-intensity continuous training in randomized controlled trials (coronary artery disease)

Study	Published yr	Sample	n	HIIT	MCT	Duration	Mode	VO2peak pre		VO2peak %increase
								HIIT	MCT	HIIT (%)	MCT (%)
1 Rognmo et al[28]	2004	CAD	17 (HIIT = 8)	3 d/wk 4 x 4 min@80%-90% VO2peak total 33min	3 d/wk 41 min@50%-60% VO2peak isoload to HIIT	10 wk	TM	31.8	32.1	17.9a	7.9
2 Warbur-ton et al[41]	2005	CAD (previous CABG or AP)	14 (HIIT = 7)	2 d/wk, 2 min@90%VO2R, 2 min recovery, 30 min total	2 d/wk 30 min @65%VO2R, average training volume similar to HIIT	16 wk	TM etc1	22	21	31.8a	9.5
3 Tjønna et al[21]	2008	Metabolic syndrome	28 (HIIT = 9)	3 d/wk 4 × 4 min@90%HRmax, 3 min active recovery @70% HRmax 40 min total	3 d/wk 47 min @70% HRmax, equalized training volume	16 wk	TM	33.6	36	35a	16
4 Moholdt et al[43]	2009	post CABG	59 (HIIT = 28)	5 d/wk 4 × 4 min@90%HRpeak, 3 min recovery	5 d/wk 46 min + Aerobic group exercise, iso energic to HIIT	4 wk	TM	27.1	26.2	12.1	8.8
5 Moholdt et al[40]	2011	post MI	89 (HIIT = 30)	2 d/wk 4 × 4 min@85%-95%HRpeak, 3 min recovery	2 d/wk 60 min@58% PPO	12 wk	TM1	31.6	32.2	14.6a	7.8
6 Rocco et al[23]	2012	CAD	37 (HIIT = 17)	3 d/wk 7 × 3 min@RCP, 7×3 min recovery@VAT total 42 min	3 d/wk 50 min@VAT	3 mo	TM	18	17.9	23.3	24.6
7 Currie et al[51]	2013	recent event CAD post PCI, CABG, etc	22 (HIIT = 11)	2 d/wk 10 × 1 min@89% (80%-104%) PPO, 1 min recovery@10%PPO, 1 d/wk home-based @similar intensity	2 d/wk 30-50 min @58% PPO, 1d/wk home-based @similar intensity not isocaloric	12 wk	bike	19.8	18.7	24	19
8 Keteyian et al[38]	2014	Stable CAD (post MI CABG and/or PCI)	28 (HIIT = 15)	3 d/wk 4 × 4 min@80%-90%HHR	3 d/wk 30 min@60%-70%HRR	10 wk	TM	22.4	21.8	16a	8
9 Madssen et al[39]	2014	CAD with stents	36 (HIIT = 16)	3 d/wk 4 × 4 min@85%-95%HRpeak, 3 min active recovery@70%HRpeak	3 d/wk 46 min@ 70%HRmax, isocaloric	12 wk	TM	31.2	29.8	10.6a	6.7
10 Conraads et al[19]	2015	CAD	173 (HIIT = 85)	3 d/wk 4 × 4 min@90%-95%HRpeak, 3 min active recovery	3 d/wk 37 min@ 70%-75% %HRmax	12 wk	bike	23.5	22.2	22.7	20.3

Adapted from Ito S et al. Internal Medicine. 2016; 55: 2329-2336.

^a in VO_2peak % increase raw: There is significant difference in % increase of VO_2peak between HIIT and MCT. 4 × 4 min means 4 × 4 min intervals per one HIIT training session. Study 2: ^a data shown is VO₂ at anaerobic threshold. Data is shown in figure without exact value at VO_2peak (30+ in HIIT 30 in MCT)., and %increase at peak exercise is similar. TM etc¹ means TM or stair climber,or, upper leg ergometer. Study 4: There was no difference at 4 wk: Increase of VO_2peak between 4 wk and 6 mo was significant within HIIT and between HIIT and MCT. The participant attended additional sessions with various intensity at the center with their choice. Exercise was performed at center for 4 wk and at home for 6 mo. Study 5: TM¹ means TM or aerobic exercise. AP: Angina pectoris; bike: Cycle ergometer; Cont: Continuous; CABG: Coronary artery bypass graft; CAD: Coronary artery disease; TM: Treadmill; HIIT: High-intensity interval training; HR_peak: Peak heart rate; HRR: Heart rate reserve; MCT: Moderate-intensity continuous training; PPO: Peak power output; RCP: Respiratory compensation point; VAT: Ventilator anaerobic threshold; VO2R: VO₂ reserve; WRp: Peak work rate.