Impact of lactate level controlled training on exercise capacity and BNP-level in heart transplant recipients

Objective: Heart rate controlled physical training is unsuitable for heart transplant recipients due to missing adrenergic innervation. Alternatively, exercise levels may be controlled by blood lactate levels. However, little is known about the impact of blood lactate controlled training on exercise capacity, neuroendocrine regulation, and quality of life after heart transplantation.

Methods: 9 heart transplant recipients (8 male, 62.2±4.5 years, mean 37.3±23.2 months after transplantation) participated in 90min training twice a week. Training focused on improvement of endurance and strength. Individual training thresholds were determined by measuring blood lactate levels during exercise (target 2mmol/l). Endurance training was conducted as interval training with successive periods of individualized submaximal and light exercise levels.

Results: After 3 months of training there was a significant increase of VO2 max (20.4±7.5 to 23.3±6.1ml/kg/min, p<0.05) and a significant increase of quadriceps muscle strength (141.3±51.2 to 166.6±59.8 Nm, p<0.03). Resting and post exercise blood levels of BNP increased significantly after 3 months (resting 44.4±19.3 to 65.7±31 and post exercise 52.1±24.2 to 88.6±37.2, p<0.01). Echocardiographic measurements and functional class showed no difference between time points. Scores for anxiety and depression showed no relevant change with 7/9 patients within normal range at baseline and after 3 months.

Conclusions: Individualized, lactate level controlled training resulted in improved exercise tolerance and increased muscle strength in heart transplant recipients. The relevance of the observed BNP-level increase in the absence of echocardiographic or functional changes and in association with controlled exercise remains to be investigated.