Table 2. Progression Models for Aerobic Exercise Training - High-Intensity Interval Training (HIIT) [37]

Patient profile	Stage of training	Prescription (weekly)	MICT	HIIT
Low functional status (< 5 METs)	Initiation (week 0-4)	2-3 × MICT	50-70% PPO (RPE: 11-15)	Not recommended
	Improvement (week 4-12)	2 × MICT and 1 × HIIT (SI)	50-70% PPO (RPE: 11-15)	HIIT-SI: 15 s to 1 min at 70-100% PPO (RPE: 15-18)
	Maintenance (week > 12)	2 × MICT and 1 × HIIT (SI + MI)	50-70% PPO (RPE: 11-15)	HIIT-MI: 1-3 min at 90-110% PPO (RPE > 15)HIIT-SI: 15 s to 1 min at 100-120% PPO (RPE: 15-18)
Normal and high functional status (≥ 5 METs)	Initiation (week 0-4)	2 × MICT and 1 × HIIT (SI)	50-70% PPO (RPE: 11-15)	HIIT-SI: 15 s to 1 min at 80-100% PPO (RPE: 15-18)
	Improvement (week 4-12)	1 × MICT and 2 × HIIT (SI + MI)	50-70% PPO (RPE: 11-15)	HIIT-MI: 1-3 min at 95–100% VO2peak (RPE > 15)HIIT-SI: 10 sec to 1 min at 100-120% VO2peak (RPE: 15-18)
	Maintenance (week > 12)	3 × MICT or HIIT (MI + LI)	50-70% PPO (RPE: 14-16)	HIIT-MI: 1-3 min at 95-100% VO2peak (RPE > 15) HIIT-LI: 3-4 min at 80-85% VO2peak (RPE > 15)

HRR: heart rate reserve, PPO: peak power output, RPE: rate of perceived exertion, METS: metabolic equivalents, MICT: moderate intensity continuous training, SI: short intervals; MI: medium intervals, LI: long intervals