Progression of aerobic exercise intensity in a cardiac rehabilitation program

To describe the progression of aerobic exercise intensity in patients on a cardiac rehabilitation (CR) program.

We conducted a retrospective analysis of a random sample of patients referred for CR after acute coronary syndrome between 2008 and 2016. The weekly peak exercise intensity achieved during aerobic exercise was estimated by treadmill speed and grade at peak effort and the corresponding perception of effort was assessed using the Borg scale. Initial exercise intensity was prescribed as 60-80% of reserve heart rate plus resting heart rate, and was modified according to perceived exertion. Peak heart rate/intensity and perceived exertion index were used as variables to characterize the response to the intensity achieved. Variables were compared at different time points: T1 (1st week), T2 (4th week) and T3 (8th week).

Of the total of 868, 238 patients were randomly selected. At peak heart rate during the session, exercise intensity (in metabolic equivalents) was: T1: 7.2±2.0, T2: 9.0±2.2, and T3: 9.4±2.2 (p<0.01). The peak heart rate/intensity index was T1: 16.8±5.4, T2: 13.4±3.6 and T3: 13.1±3.8 (p<0.01) and the perceived exertion index was T1: 1.8±0.6; T2: 1.4±0.5; T3: 1.4±0.5 (p<0.01).

Increasing exercise intensity during CR, associated with lower perception of effort and lower heart rate necessary to achieve such intensity, leads to significant improvement in functional capacity.