Table 1

Comparison of HIIT and MISS training interventions

HIIT	MISS
Exercise sessions conducted as follows: Warm up: 15 min total, 10 min <40% HRR, 5 min <70% HRR. Cardiovascular component: exercise cycle ergometer interval training (Wattbike Trainer; Wattbike, Nottingham, UK): high=85–90% PPO from CPET, low=20–25% PPO (exercise intensity will not to be prescribed from gas exchange data, ie, %VO_{2 peak}). Change in intensity from low to high achieved by altering cadence (rpm). Exercise HR will not exceed HR_max from CPET. Cool down: 10 min, <40% HRR. Duration of intervals and total programme duration increased within a standardised framework (table 2). Workload increased bi-weekly in response to participant reported RPE (only after the full 10×1 protocol has been achieved). If RPE <17 during the last two high-intensity intervals, then workload will be increased.	Exercise sessions conducted in accordance with BACPR/ACPICR standards,29 adhering to the following key principles: Warm up: 15 min, <40% HRR. Cardiovascular component: moderate-intensity interval training progressing towards 20–40 min continuous cardiovascular exercise at 40–70% HRR (from CPET) and RPE 12–14. Cool down: 10 min, <40% HRR. Initial duration based on participant's previous and current PA levels and CPET performance. Duration and workload of cardiovascular component adjusted, as tolerated, within the above parameters, in response to exercising HR, participant reported RPE and symptoms. As per current practice, priority will be given to increasing duration until 20 min of continuous exercise has been achieved. Thereafter, workload can be increased in conjunction with duration.

HIIT

MISS

Exercise sessions conducted as follows:
1. Warm up: 15 min total, 10 min <40% HRR, 5 min <70% HRR.
2. Cardiovascular component: exercise cycle ergometer interval training (Wattbike Trainer; Wattbike, Nottingham, UK):
  high=85–90% PPO from CPET, low=20–25% PPO (exercise intensity will not to be prescribed from gas exchange data, ie, %VO_{2 peak}). Change in intensity from low to high achieved by altering cadence (rpm). Exercise HR will not exceed HR_max from CPET.
3. Cool down: 10 min, <40% HRR.
Duration of intervals and total programme duration increased within a standardised framework (table 2).
Workload increased bi-weekly in response to participant reported RPE (only after the full 10×1 protocol has been achieved). If RPE <17 during the last two high-intensity intervals, then workload will be increased.

Exercise sessions conducted in accordance with BACPR/ACPICR standards,29 adhering to the following key principles:
1. Warm up: 15 min, <40% HRR.
2. Cardiovascular component: moderate-intensity interval training progressing towards 20–40 min continuous cardiovascular exercise at 40–70% HRR (from CPET) and RPE 12–14.
3. Cool down: 10 min, <40% HRR.
Initial duration based on participant's previous and current PA levels and CPET performance.
Duration and workload of cardiovascular component adjusted, as tolerated, within the above parameters, in response to exercising HR, participant reported RPE and symptoms. As per current practice, priority will be given to increasing duration until 20 min of continuous exercise has been achieved. Thereafter, workload can be increased in conjunction with duration.

CPET, cardiopulmonary exercise test; HIIT, high-intensity interval training; HR, heart rate; HRR, heart rate reserve; MISS, moderate-intensity steady state; PA, physical activity; PPO, peak power output; RPE, rating of perceived exertion; VO_{2 peak,} peak oxygen uptake.