Exercising to Lose Fat Doesn't Affect Bones

Discrediting the myth that exercising to lose extra body fat is detrimental to bone health, researchers have revealed that for those individuals aged 55 to 75, a moderate physical exercise regiment typically maintains bone mass, and is some circumstances, offers modest improvements.

In a study published in the June 2005 issue of the American Journal of Preventative Medicine, scientists at Johns Hopkins University (Baltimore, MD, USA) reported that after six months of aerobic exercise on a bicycle, treadmill, or stepper, and adding weightlifting, individuals experienced better overall fitness and fat loss without a lot of change in bone mineral density. A more detailed study showed slight increases in bone mass, of 1-2%, for those who exercised the most and demonstrated the greatest increase in muscle strength, aerobic fitness, and muscle tissue.

Bone scans were taken using bone densitometry (DXA) imaging to evaluate bone mineral density. In both men and women who exercised and lost weight, overall bone density did not alter, even though results were mixed for women in certain areas of the hip. However, those who demonstrated the greatest gains in fitness had modest increases in bone density at several sites, and loss of body fat was not tied to bone loss.

For a six-month period, the Hopkins group evaluated the benefits of a supervised program of exercise training in a group of 104 older men and women, evaluating both fatness and fitness levels at the start and end of the study. Half were randomly placed in a widely recommended moderate exercise program, thought whereas the rest maintained their usual physical routine and diet.

Substantial improvements were observed in active participants' body fat, and muscle and fitness levels. Aerobic fitness, as measured by peak oxygen uptake on a treadmill, increased by 16%, and strength fitness increased by 17%. The median weight loss in this group was only four pounds, because much of the loss of fat was counterbalanced by increased muscle mass. The fat in the abdominal area, assessed by magnetic resonance imaging (MRI), was reduced by 20% among exercisers. The group that was not exercising had either no or considerably less improvement than the exercising group.

The investigators added that whereas bone mass did not increase in this program, there are other benefits that will probably reduce the risk of fractures. Bones typically break after a fall, a key risk factor for fractures in older adults. However, exercise makes bodies stronger and improves balance, thereby preventing falls.




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