Many studies have suggested that the positive effect of running on bone mass does not fully compensate for the negative effects of athletic amenorrhea. These studies have made this conclusion based on measurements of bone at a limited number of sites. This study used dual-photon absorptiometry to measure bone mineral content and bone mineral density in the total body as well as in several regions in amenorrheic runners (N = 13), eumenorrheic runners (N = 13), and sedentary controls (N = 12). The subjects were 21-35 years old. Runners had run at least 40 km/week for at least the past 3 years. Controls had body mass indices similar to those of the runners. The amenorrheic women had significantly lower values for total bone mineral content (P = .01), total bone mineral density (P = .04), and total bone mineral content as a percent of normal values (P = .04) than eumenorrheic women, but they were not significantly different from the controls. When total bone mineral content and total bone mineral density were adjusted for body weight, there were no significant differences among the groups. The eumenorrheic subjects had significantly greater bone mineral density in the trunk than the amenorrheic women; eumenorrheics and controls had significantly greater bone mineral density in the spine compared with amenorrheics. Lumbar spine bone mineral density showed a trend toward greatest values for controls and lowest for amenorrheic women (P = .069), although this measurement is relatively imprecise. Arms and legs showed no significant differences among the groups. Despite their physical activity, amenorrheic runners have a lower total body bone mineral density than their eumenorrheic counterparts and lower bone mineral density in the trunk and spine regions of the body. However, the lower values seem proportional to their lower body weight.
(C) 1992 The American College of Obstetricians and Gynecologists