(HealthDay News) -- Doing weight-bearing exercise during adolescence may help women maintain their bone strength in old age, a new study says.

Published online Dec. 22 in the British Journal of Sports Medicine, the Japanese study drew its conclusions by looking at the teenage exercise habits of 46 postmenopausal women, now aged 52 or older.

Those who had participated in low-impact, weight-bearing exercise, such as swimming, while younger had significantly greater bone mineral content in both the spine and the thigh bone. The other women in the study had either played more high-impact sports in their youth that involved running or jumping, such as volleyball or tennis, or no sports at all.

Those in the weight-bearing group also had larger outer femoral bone area, which would help protect them more from fracture during pressure from movements, such as bending.

As none of the women with the strongest bones were taking part in any weight-bearing exercise programs at the time of the bone density study, the Suzuka University of Medical Science authors suggest their exercising in their youth helped them more than 40 years later.

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By Kevin McKeever