In masters runners, bone mass is what it used to be. (Foundations for Fitness).

In January researchers in California addressed concerns that chronic running may not prevent bone mineral density loss in women over 40, and may even inhibit the effects of hormone replacement therapy (HRT).

The researchers had hypothesized that, at the very least, the postmenopausal runners not replacing estrogen would experience significant bone mineral density loss. Other studies, including one from the same laboratory, have concluded that chronic running was not beneficial and possibly detrimental to bone strength in middle-aged and older women. But 41 female masters runners were found to maintain bone mass over a five-year period, regardless of menstrual or HRT status.

The January research, which was set up to test running alone and running in combination with HRT in both pre- and postmenopausal women, measured VO2max, training intensity, body composition, nutritional history and bone mass for each woman twice, five years apart. Fitness and training variables were not different among just-runners and runners with HRT in both the pre-and postmenopausal groups, and did not change over time. Body composition was different among groups but not over time. Calcium intake did not differ among groups but increased over time. Bone mineral density of the hip, spine and whole body were different between groups, but did not change significantly over time. Chronic running did not inhibit or enhance the effect of HRT on bone. Statistical analysis revealed age as the only significant predictor of change in bone mass.

Explanations for the previous findings could include a detrimentally low body mass in chronic runners, nutritional deficits (including low calorie and calcium intake) and "disruption of the normal hormonal milieu." However, the onset of running needs to be associated with loss of bone mass to establish causation, and human studies have yet to demonstrate this. They have shown quite the contrary, in fact (see Running & FitNews, Mar/Apr 2003). The researchers conclude: "This study provides support for chronic running as an effective means to maintain skeletal health in middle-aged and older women."

(Med. Sci. Sports & Exerc., 2003, Vol. 35, No. 1, pp. 137-144)

RELATED ARTICLE: Men Go Undertreated For Osteoporosis

Men are far less likely than women to receive treatment for osteoporosis following a hip fracture. After reviewing the medical records of 363 hip fracture patients over age 50, researchers discovered that only 4.5% of the men but 27% of the women received bone-protective medication, whether in the form of HRT or through vitamin D and calcium supplements. At 1- to 5-year follow-up, 71% of the women were being treated for osteoporosis, and only 27% of the men.

(Archives of Internal Medicine, 2002, Vol. 162, No. 19, pp. 2217-2222)