Moderate endurance training has no effect on the parathyroid function of heart transplant patients

The benefit of retraining for heart transplant recipients (HTR) is now well established. The rehabilitation of these patients can be compromised by osteopenia and bone fractures. The resting levels of parathyroid hormone (PTH) and exercise-induced increases are higher in HTR than in healthy controls. To evaluate the effect of a moderate endurance training programme on parathyroid activity, six HTR, an average of 18 months after transplant, and seven healthy sedentary controls have been studied. None of the subjects had a history of bone disease. Two exercise tests (square wave endurance exercise tests, SWEET) with identical work rates were performed before and after training. Intact PTH, ionized calcium (Ca2+), phosphorus (Pi) and pH were measured at rest, during exercise and in the recovery periods. Training consisted of a 45-min SWEET three times a week for 6 weeks. Levels of Ca2+, Pi and PTH showed a significant increase during the exercise session in both groups. Ca2+ and Pi levels decreased rapidly after the cessation of exercise whereas PTH reached a peak at the 10th min of the recovery in both groups. This increase in PTH was significantly higher in HTR than in controls. However, despite a significant improvement of total endurance work (+ 28% in HTR, +29% in controls) this endurance training had no effect on resting levels of PTH, plasma Ca2+ or Pi, nor on their exercise-induced variations. The exercise-induced decrease in pH was less pronounced after training which is evidence of training. We conclude that a short endurance training programme does not alter the moderate hyperparathyroidism of HTR. The effect of such a training programme on bone mass and bone mineral density needs now to be evaluated.