High versus low training frequency in cardiac rehabilitation using a systems model of training

No study has reported the long term effects of cardiac rehabilitation, concerning the duration of beneficial effects of training program. The present study analyzed the influence of training session frequency on long-term beneficial effects in patients with coronary artery disease (CAD) undergoing phase 2 cardiac rehabilitation. Four patients with CAD completed 20 training sessions. Two patients were assigned to low training frequency (LTF) and two to high training frequency (HTF): three and five sessions per week(-1), respectively. The method was based on the systems model of training and required training quantification and the assessment of real exercise tolerance. Convolution of training quantity with real exercise tolerance provided the model exercise tolerance for every patient. The model parameters, the magnitude factor (k), and the time constant of decay (tau), were fitted from real and model exercise tolerances by the least squares method. LTF and HTF resulted in similar increases in exercise tolerance (12-14%). A model with one-component (fitness) allowed fitting exercise tolerance in all patients with r (2) = 0.77, 0.79, 0.84, and 0.91, respectively (p < 0.05). The addition of a second component did not improve the fit in any patient (p > 0.05). The k value was about twice as high with LTF (0.13 and 0.16 AU) than with HTF (0.05 AU for the two patients), whereas the tau value was about twice as low with LTF (37 and 41 days) than with HTF (72 and 89 days). The long term beneficial effects estimated by 4tau, were twice as long with HTF (288 and 356 days) than with LTF (148 and 164 days). We concluded that exercise tolerance was similarly increased with HTF and LTF but HTF training induced beneficial effects which were sustained twice as long.