Strength Training Increases Bone Mineral Density In Postmenopausal Women

Strength training over a period of time will prevent not only the loss of bone mineral density, but also will work to build bone matter, new research shows. A comprehensive study published in the January 2003 issue of Medicine & Science in Sports & Exercise® reinforces the positive link between muscle-strengthening and osteoporosis prevention in women. The study also indicates a significant, progressive relationship between total weight lifted by calcium-replete postmenopausal women and an increase in bone mineral density (BMD).

"Because of the relationship between the amount lifted over a year's time, and the actual amount of bone mass gained, women can decrease their risk of osteoporosis and bone fracture by working regular muscle-strengthening exercises into their health and fitness routine, and sustaining that routine over a period of time," said Timothy Lohman, Ph.D., the lead author of the study.

Increased BMD is typically the end goal of hormone replacement strategies traditionally used to prevent osteoporosis. However, faced with the ever-increasing costs of medications along with the undesirable side-effects of such programs, scientists are now focusing their osteoporosis prevention efforts on alternative methods of building bone mass.

The study was performed by researchers at the University of Arizona Departments of Physiology and Nutritional Sciences, and is part of the Bone, Estrogen, and Strength Training (BEST) Study. Eight core exercises were selected to isolate and strengthen the small and large-muscle groups that support the spine and hip, key areas associated with osteoporotic fractures. The study was designed to examine the possibility of an exercise relationship at two hip sites (femur trochanter and femur neck), the lumbar spine, and the total body.

More than 140 sedentary, postmenopausal, but otherwise healthy women were recruited. Participants in the study took part in the year-long monitored program of strength training exercises, attending two to three sessions per week. The women were also provided with calcium supplements.

Results of bone scans taken before and after the exercise period were compared, and the impact of each exercise on each measurement site was assessed. The most significant increase in BMD was found in the hip site known as the femur trochanter, one of the most important weight bearing structures in the body. The exercise found to have the most impact on this BMD increase was weighted squats, while weighted march seemed to positively impact total body BMD most.

Also, the more total weight the women lifted in one year, the greater the increase in BMD in the femur trochanter. This is the first study to report such a relationship between total weight-lifted and bone density increase.

Despite the impact of these particular exercises, especially on the femur trochanter, other exercises seemed to have little or no impact and positive results were not observed at other measurement sites such as the femur neck and lumbar spine. The authors however observed that the individual exercises should not be considered unrelated to the total exercise program.

"Since each of the individual exercises could have an effect on the others and on each of the bone sites measured, the most sensible approach to osteoporosis prevention is a well-balanced strength training program," added Lohman.

The authors also noted other lifestyle changes, such as the adequate intake of calcium from diet and supplementation, cessation of smoking, and moderation in alcohol consumption are other cost-effective alternatives to drug therapy.

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