Walking, jogging fail to prevent bone turnover

Walking

If you think it is only good to lose weight by jogging and fast walking, then here's the twist in the tale—such weight-bearing exercises fail to prevent the increased bone turnover caused by weight loss, University of Missouri researchers have found.

During weight loss, bones are being remodelled – breaking down old bone and forming new bone – at an accelerated rate. As a result, bone density is reduced, causing increased fragility.

"Accelerated bone turnover is not favorable, but the potential negative consequences of increased bone turnover do not outweigh the numerous other health benefits of weight loss. Adequate intake of calcium and vitamin D may minimize the reduction in bone density during weight loss," said Pam Hinton.

The researchers examined bone turnover markers in the blood of overweight, premenopausal women. These bone markers, which are released by the bone cells that are involved in bone breakdown and formation, are used as indirect indicators of bone remodelling.

After six weeks, women who lost 5 per cent of their body weight by adhering to a calorie-restricted diet and participating in weight-bearing exercise experienced an increase in bone turnover markers.

The researchers observed the same increase in markers among women who also lost 5 per cent of their body weight by calorie-restriction only or by dieting and participation in non-weight-bearing exercise.

The findings indicate that low-impact, weight-bearing exercise, such as slow jogging, does not prevent the increase in bone turnover associated with modest weight loss.

"These findings should not affect the prescription for aerobic exercise during weight loss. The rationale for recommending aerobic exercise during weight reduction is to increase energy expenditure and maintain lean body mass," said Hinton.

In previous studies, researchers found that weight-bearing exercise promotes bone building, which suggested that this type of exercise would prevent bone turnover in weight loss, said Hinton.

Future studies will examine the ability of high-impact, weight-bearing exercise to maintain normal bone turnover during weight loss.

The study was published in Applied Physiology, Nutrition and Metabolism.