Abstract

It seems likely to consider that the bone density (BD) of athletes is higher than that of control subjects. But recently, many authors reported lower BD of amenorrheic female athletes, and suggested that strenuous exercise could decrease BD through, probably, endocrinological disorder. So, we compared BD of second metatarsal in female athletes with irregular menstrual cycle (IM group) or with stress fracture (SF group) to that of normal menstrual athletes (NM group) or those without bony injuries (NF group), by MD/MS method. MD/MS method, which is the screening method of BD by scanning mid-diaphysis of second metacarpal (or metatarsal) for 3 cm by 20 times in X-ray films, was developped from microdensitometry whose scanning was only once at the same part of the bone. BD of IM group was lower than that of NM group, but without significant difference. BD of SF group was significantly lower than that of NF group. The index of mechanical strength of the bone, I, that is area moment of inertia, did not increase in accordance with decrease of BD. We speculate this as one of the factor of stress fracture in a sense of decreased mechanical strength. Verf.-Referat