The present study was designed to evaluate the effects of 6-wk endurance training on serum parathyroid hormone (PTH) levels and on other parameters at rest and after a maximal exercise test (MET) in 24 55- to 73-yr-old men. Before training, MET was found to induce a significant increase in PTH levels as compared with resting values. This MET-induced rise in PTH was accompanied by enhanced total calcium, phosphate, alkaline phosphatase (ALP), osteocalcin, and albumin levels. After the training period (75-80% maximal heart rate, 1 h.d-1, 4 d.wk-1), the changes induced by MET in calcium, phosphate, ALP, and albumin levels followed the same pattern as before training. Conversely, the MET-induced increase in PTH levels was found markedly more pronounced after training than in untrained conditions (+21.9% vs +11.1%, respectively, P < 0.05). Furthermore, lower values of osteocalcin were found after training as compared with pretraining values, both at rest and after maximal exercise. These findings indicate that 6 wk of endurance training enhanced exercise-related release of PTH and reduced osteocalcin levels in elderly men. This might be of importance regarding bone status in the elderly, as exercise is proposed as a preventive measure against osteopenia.