BONE-MINERAL DENSITY IN MATURE, PREMENOPAUSAL ULTRAMARATHON RUNNERS

We measured bone mineral density (BMD) in 25 premenopausal ultramarath on (56 km) runners aged 29-39 yr and related risk factors for decrease d BMD with actual BMD. Fifteen runners who had never had oligo/amenorr hea (R) were compared with 10 runners (OA): 4 oligomenorrheic, 2 ameno rrheic, and 4 with prior oligo/amenorrhea. Menstrual, dietary and trai ning data were obtained. BMD of the lumbar spine (LS) and proximal fem ur (F) were measured by dual energy x-ray densitometry. Both groups ha d similar body mass (58 +/- 8 vs 57 +/- 8 kg), running and dietary his tories. F BMD was not different (P = 0.07) and correlated only with BM I (P < 0.05; r = 0.43). LS BMD was lower in OA (0.946 +/- 0.098 g . cm -2) than R (1.088 +/- 0.069 g . cm(-2); P < 0.001). Menstrual History Index (MHI), (estimated periods . yr(-1) since age 13), was higher in R (11.6 +/- 0.6) than OA (9.4 +/- 2.1; P < 0.01). LS BMD correlated wi th MHI (P < 0.0005; r = 0.67) and years oligomenorrheic (P < 0.01; r = -0.58) but not years amenorrheic, parity, breastfeeding, diet, or tra ining. In conclusion, in mature women distance runners low LS BMD is r elated to a history of oligo/amenorrhea regardless of resumption of re gular menstrual cycles in some subjects. Not only amenorrhea, but also prolonged oligomenorrhea may negatively influence peak adult bone mas s.