Mechanisms responsible for enhanced stroke volume after exercise training in coronary heart disease

High intensity endurance exercise training increases maximal attainable O₂ uptake (VO₂(max)) and stroke volume (SV) in patients with ischaemic heart disease. To determine the mechanisms responsible for enhanced SV after training, 18 patients, 51 ± 3 years (mean ± SE) were studied. Patients completed 12 months of endurance exercise with a peak intensity of 89.7 ± 2% of attainable VO₂(max). Attainable VO₂(max) increased from 23 ± 1 to 32 ± 2 ml/kg/min (P < 0.0001). Left ventricular function was assessed using radionuclide ventriculography. To control for afterload, haemodynamic variables were evaluated at comparable mean blood pressure (mBP). SV was increased after training both at rest (77 ± 3 vs 81.5 ± 5 ml; P < 0.025) and during exercise (78 ± 6 vs 93 ± 6 ml; P < 0.025) at comparable mBP. Before training, ejection fraction decreased during exercise (59 ± 3 vs 55 ± 3%, P < 0.005) but increased after training from the resting level (59 ± 3 vs 63 ± 3%, P < 0.025). Left ventricular end diastolic volume during exercise did not change. Thus, the results suggest that enhanced SV during exercise is, in part, due to improved left ventricular function after exercise training.