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BACKGROUND: Rapid bone loss occurs early after heart transplantation. There is no standard therapeutic intervention to prevent osteoporosis in heart transplant recipients (HTR). The purpose of this study was to determine the effectiveness of a regimen combining the antiresorptive properties of nasal calcitonin with the osteogenic stimulus of resistance exercise. METHODS: Eighteen candidates for heart transplantation were randomly assigned either to a group that received calcitonin and participated in 6 months of resistance exercise (n=10) or to a group that received only calcitonin (n=8). Calcitonin therapy (200 IU daily for 8 months) was initiated 48 hr after transplantation. Resistance exercise was initiated 2 months after transplantation. Bone mineral density (BMD) of the total body, femur neck, and lumbar vertebra (L2-3) were assessed before, and at 2 and 8 months after transplantation. RESULTS: Total body and femur neck BMD did not decrease (P>or=0.05) below pretransplantation values at 2 months after transplantation in either group. BMD of the lumbar spine was significantly (P<or=0.05) and comparably decreased at 2 months after transplantation in the calcitonin (-10.1+/-1.8%) and calcitonin + training groups (-12.9+/-2.7%). At 8 months after transplantation lumbar BMD was -16.9% below pretransplant values in the calcitonin group. In contrast, lumbar BMD was restored to within 5% of pretransplant levels in the calcitonin + training group. CONCLUSIONS: Calcitonin attenuates BMD loss in the total body and femur neck but not in trabecular bone of the lumbar vertebra. Mechanical loading, through progressive resistance exercise, is an osteogenic stimulus in HTR.