The effect of combined exercise training on exercise intolerance and cardiovascular health outcomes in adults living with atrial fibrillation.

Combined exercise training (CT): For participants randomised to the CT group, exercise training will be completed 3 days per week for 12 weeks (36 sessions), with 2 sessions per week to be completed as group sessions (no more than 4-5 participants per group) face-to-face supervised sessions with an Accredited Exercise Physiologist in the Institute for Physical Activity and Nutrition's (IPAN) exercise lab and gym and 1 session to be performed as an individual unsupervised session at home. The 2 face-to-face supervised sessions per week will incorporate both aerobic and resistance training components and the 1 unsupervised session per week will be aerobic training only. Session 18 will involve supervised retesting of cardiorespiratory fitness and muscular strength to modify individual exercise prescriptions due to any changes in fitness levels. All supervised exercise sessions will take 45-60 mins, with all unsupervised MIIT sessions taking 20-30 mins in duration. Moderate-intensity interval training (aerobic training): For the aerobic training component, participants will complete moderate intensity-interval training (MIIT), with a 3 minute warm-up and cool-down to be performed at each session at a light- to moderate-intensity (45-50% HRR, or Borg’s Rating of Perceived Exertion [RPE] of 10-11/20) prior to and immediately following MIIT, respectively. This will involve a gradual increase in intensity during the warm-up and a gradual reduction in intensity during the cool-down to avoid vasovagal events or syncope This will be completed on an aerobic exercise mode of the participant’s choice (e.g. walking, cycling, aerobic stepping, rowing etc.) during supervised and unsupervised sessions. Sessions 1-5: 4x4 minute moderate-intensity intervals (70-75% heart rate reserve [HRR], RPE: “somewhat hard”, 13-14/20), interspersed with 2-minute active recoveries ( or 50-55% HRR or an RPE at “light” exertion, 11-12/20). Sessions 6-11: MIIT will be progressed to 4x5 minute MIIT with 2 minutes of active recoveries at the same prescribed intensities in Sessions 1-5. Sessions 12-17: MIIT will be progressed to 4x5 minute MIIT with 1 minute of active recovery at the same prescribed intensities in Sessions 1-5. Sessions 19-23: will repeat the same exercise prescription of Sessions 1-5, with exercise intensity to be prescribed based off retesting results obtained from Session 18. Sessions 24-29: will repeat the same exercise prescription from Sessions 6-11, with exercise intensity to be prescribed based off retesting results obtained from Session 18. Sessions 30-36: will repeat the same exercise prescription from Sessions 12-17, with exercise intensity to be prescribed based off retesting results obtained from Session 18. Resistance Training: For the resistance training component of the exercise session exercise prescription will follow a “cluster sets” training model which can be defined as a pre-planned rest period between a single or groups (“cluster”) of repetitions within a set. This is in contrast to traditional resistance training whereby all repetitions within a set are completed in succession without a rest period. Participants will complete 6 resistance training exercises: chest press, seated row, leg press, knee extension, shoulder press and biceps curl. All exercises will be performed 3 sets of 8 repetitions at 70% 1RM or an RPE of 13-14/20 with 1 minute of passive recovery between sets. Each cluster will be performed as 2x4 repetitions with 30 seconds passive recovery in-between. Previous research in cardiac population groups like atrial fibrillation have shown that hemodynamic responses (blood pressure responses) to resistance training are significantly lower and within a safe range when performed at lower repetition ranges, than high repetition ranges (>11 repetitions performed consecutively), regardless of the intensity prescribed. The intensity of the exercises will increase every 2 weeks: Week 3-4, 75% 1RM; Week 5-6 80% 1RM; Week 7-8: retested 70% 1RM; Week 9-10: retested 75% 1RM; Week 11-12: retested 80% 1RM. Adherence and compliance to exercise training will be determined by: (i) the completion of number of scheduled sessions attended at the gym as well as Polar HR monitoring data entry for the unsupervised MIIT session; (ii) completing the full duration and intensity of the MIIT component as recorded by HR and RPE; (iii) the number of sets and repetitions completed at the prescribed intensity during the resistance training component.