Running, Calcium, and Resistance Training Slow Bone Mineral Density Loss in Females
Abstract & Commentary
Synopsis: Long-distance running did not increase age-related bone loss in females, irrespective of hormonal replacement therapy or menstrual status.
Source: Hawkins SA, et al. Five-year maintenance of bone mineral density in women master runners. Med Sci Sports Exerc. 2003;35(1):137-144.
Several research reports have suggested that long-distance running may not prevent age-related bone loss in women, may predispose one to osteopenia, or may inhibit the influence of hormone replacement therapy (HRT) on bone. Therefore, the purpose of this study was to determine the effect of long-distance running in 41 women’s masters runners with and without HRT, on bone mineral density (BMD) in pre- and postmenopausal women. Over approximately 5 years the women were tested for body composition, maximal aerobic capacity, bone density, training history, and nutritional and menstrual history.
Although some group differences existed for body mass and body composition, they did not change over time. Fitness and training variables were similar between groups and did not change over the time of the study. Calcium intake was similar between the groups and increased over the 5 years of the study. Although the BMD of the hip, spine, and whole body were different between groups, it did not change significantly over time. Statistical analysis supported that age was the only significant predictor of changes in bone between the groups and that exercise did not decrease bone density. Hawkins and colleagues, therefore, concluded that their data demonstrate no significant loss of bone mass over a 5-year period in these masters-level runners with relatively high calcium intakes regardless of menstrual or HRT status. Additionally, the effect of HRT on bone in these runners was not affected.
Comment by James R. Slauterbeck, MD
Osteoporosis is very prevalent among adult females. Findings that running in elderly females may decrease bone mass could have a huge negative effect on the overall health of the aging female population. Some of the prior studies indicating that bone density is decreased many have been flawed by design because they did not adequately determine that BMD decreased with the onset of running or that bone mineral loss rates in runners were greater than a similar group of sedentary people. Additionally, some recent reports are questioning the efficacy of ERT on the adult females because of cancer and other risks. Therefore, this article will help determine if runners not on ERT are placing themselves at greater than expected BMD loss.
The average BMD loss per year in these masters runners was less than that of the reported value for the average middle-aged woman (0.8 - 1.2%/yr). However, some study design issues must be discussed. Some of the women did some resistance training (40%) in addition to their running programs. Since resistance training is known to increase bone mass, the effect of resistance training on this study does cloud some of the conclusions. Additionally, most of these runners were on calcium supplementation, and the effect of dose was not controlled. Seventy-five percent of the women in this study met the RDA for calcium supplementation. It is not clear from this article if the effect of calcium could prevent bone loss without exercise or without resistance training, but the effect of all 3 clearly decreases BMD loss. In my opinion, the strengths of the article far outweigh the above concerns. The identification of subjects, testing methods, and data presentation were sound. It is difficult to find women who only run and do not resistance train, and it is equally hard to find women who all take similar supplements.
Therefore, my assessment of this article is that it shows the benefits of running, nutrition, and resistance training in the middle-aged athletic woman to maintain bone mass regardless of menstrual or estrogen replacement status. I support and encourage my active female patients to run, lift weights, and supplement their diets with calcium. Additionally, in these women who cannot take ERT, BMD can be maintained with exercise and calcium supplementation better than the average person. One can only surmise that limiting BMD loss over time will decrease hip fractures in the elderly and ultimately lead to a healthier aging population.
Dr. Slauterbeck is Associate Professor, Department of Orthopaedic Surgery, Texas Tech University Health Sciences Center, Lubbock, TX.
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