Different Endurance Training Protocols in Cardiac Rehabilitation

It is the aim of the study to compare the effects of 6 weeks of either high-intensity interval training (HIT; carried out at correctly assessed 85-95% of maximal heart rate), pyramid, or continuous endurance training, on changes of physical exercise capacity in cardiac patients. The three exercise arms (isocaloric) are composed as follows: Endurance training (n=15): 31min at 65-75% HRmax; HIT (n=15): 4x4min intervals at 85-95% HRmax divided by 3x3min of active recovery at 60-70% HRmax, making it a total of 25min; Pyramids (n=15): One Pyramid consists of 8 one-minute blocks. Those are grouped starting with one block of 70-75% HRmax, followed by one block at 75-80% HRmax and another one at 80-85% HRmax. The top of the pyramid are 2 blocks of 85-90% HRmax. Intensity is lowered afterwards with one block at 80-85% HRmax, followed by one block at 75-80% HRmax and last one at 70-75% HRmax. Two more pyramids follow, each divided by 2min of active recovery at 65-70% HRmax, making it a total of 28min. All protocols are initiated by 5min of warm-up and end with 5min of cool-down, both at 60-70% HRpeak. Primary Outcome: Individual maximum power output in watt (Pmax). Secondary Outcome: Change of power output in watt at lactate thresholds at 2 and 4 mmol/l.