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Resistance exercise training restores bone mineral density in heart transplant recipients
R W Braith1, R M Mills, M A Welsch
1Center for Exercise Science, College of Health and Human Performance, University of Florida, Gainesville 32611, USA.
Objectives:
This was a prospective, randomized, controlled study designed to determine the effect of resistance exercise training on bone metabolism in heart transplant recipients.
Background:
Osteoporosis frequently complicates heart transplantation. No preventative strategy is generally accepted for glucocorticoid-induced bone loss.
Methods:
Sixteen male heart transplant recipients were randomly assigned to a resistance 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 body, femur neck and lumbar spine (L2 to L3) was measured by dual-energy X-ray absorptiometry before and 2 months after transplantation and after 3 and 6 months of resistance exercise or a control period. The exercise regimen consisted of lumbar extension exercise (MedX) performed 1 day/week and variable resistance exercises (Nautilus) performed 2 days/week. Each exercise consisted of one set of 10 to 15 repetitions performed to volitional fatigue.
Results:
Pretransplantation baseline values for regional BMD did not differ in the control and training groups. Bone mineral density of the total body, femur neck and lumbar vertebra (L2 to L3) were significantly decreased below baseline at 2 months after transplantation in both the control (-3.3 +/- 1.3%, -4.5 +/- 2.8%, -12.7 +/- 3.2%, -14.8 +/- 3.1%, respectively). Six months of resistance exercise restored BMD of the whole body, femur neck and lumbar vertebra to within 1%, 1.9% and 3.6% of pretransplantation levels, respectively. Bone mineral density of the control group remained unchanged from the 2-month posttransplantation levels.
Conclusions:
Within 2 months after heart transplantation, approximately 3% of whole-body BMD is lost, mostly due to decreases in trabecular bone (-12% to -15% of lumbar vertebra). Six months of resistance exercise, consisting of low back exercise that isolates the lumbar spine and a regimen of variable resistance exercises, restores BMD toward pretransplantation levels. Our results suggest that resistance exercise is osteogenic and should be initiated early after heart transplantation.