BACKGROUND: A paucity of studies has examined the effect of exercise training after left ventricular assist device (LVAD) implantation. Previous research has demonstrated that insertion of the LVAD alone improves exercise capacity and quality of life (QOL). This study investigated whether supervised exercise training results in a further improvement. METHODS: This prospective, randomized controlled trial with concealed allocation, assessor blinding, and intention-to-treat analysis investigated the effect of exercise training on exercise capacity and QOL in 14 patients who underwent LVAD insertion as a bridge to heart transplantation. Exercise training consisted of 8 weeks of gym-based aerobic and strengthening exercises 3 times a week, with a progressive mobilization program, compared with the control group that completed mobilization alone. Exercise capacity was measured before and after the intervention using maximal cardiopulmonary exercise testing and 6-minute walk distance (6MWD). QOL was measured using the Short Form 36-item assessment. RESULTS: No adverse events were reported. There was a trend toward greater improvement in peak oxygen consumption (Vo(2)), 6MWD, and QOL in the exercise group (n = 7) compared with the control group (n = 7); however, no significant between-group difference was detected for improvements in peak Vo(2) [mean difference (exercise--control)] of 2.96 ml/kg/min (95% confidence interval, -1.04 to 6.97), 6MWD at 54 meters (-51 to 159 meters), and QOL scores over time (p > 0.05). CONCLUSION: Exercise training is feasible and safe in patients with a LVAD. Trends toward greater improvement in exercise capacity and QOL after exercise training warrant further investigation in a larger trial.