RESISTANCE EXERCISE TRAINING RESTORES BONE-MINERAL DENSITY IN HEART-TRANSPLANT RECIPIENTS

Objectives. This was a prospective, randomized, controlled study desig ned to determine the effect of resistance exercise training on bone me tabolism in heart transplant recipients. Background Osteoporosis frequ ently complicates heart transplantation. No preventative strategy is g enerally accepted for glucocorticoid-induced bone loss. Methods. Sixte en male heart transplant recipients were randomly assigned to a resist ance exercise group that trained for 6 months (mean [+/- SD] age 56 +/ - 6 years) or a control group (mean age 52 +/- 10 years) that did not perform resistance exercise. Bone mineral density (BMD) of the total b ody, femur neck and lumbar spine (L2 to L3) was measured by dual-energ y X-ray absorptiometry before and 2 months after transplantation and a fter 3 and 6 months of resistance exercise or a control period. The ex ercise regimen consisted of lumbar extension exercise (MedX) performed 1 day/week and variable resistance exercises (Nautilus) performed 2 d ays/week. Each exercise consisted of one set of 10 to 15 repetitions p erformed to volitional fatigue. Results. Pretransplantation baseline v alues for regional BMD did not differ in the control and training grou ps. Bone mineral density of the total body, femur neck and lumbar vert ebra (L2 to L3) were significantly decreased below baseline at 2 month s after transplantation in both the control (-3.3 +/- 1.3%, -4.5 +/- 2 .8%, -12.7 +/- 6.2%, respectively) and training groups (-2,9 +/- 1.1%, 5.9 +/- 3.2%, -14.8 +/- 3.1%, respectively). Six months of resistance exercise restored BMD of the whole body, femur neck and lumbar verteb ra to within 1%, 1.9% and 3.6% of pretransplantation levels, respectiv ely. Bone mineral density of the control group remained unchanged from the 2-month posttransplantation levels. Conclusions. Within 2 months after heart transplantation, similar to 3% of whole-body BMD is lost, mostly due to decreases in trabecular hone (-12% to -15% of lumbar ver tebra), Six months of resistance exercise, consisting of low back exer cise that isolates the lumbar spine and a regimen of variable resistan ce exercises, restores BMD toward pretransplantation levels. Our resul ts suggest that resistance exercise is osteogenic and should be initia ted early after heart transplantation.