Knoglemetabolisme hos kvindelige løbere. Langdistanceløbere har hyppigt menstruationsforstyrrelser, men knoglemassen er upåvirket, undtagen hos løbere med amenoré

The purpose of the study was to investigate the prevalence of exercise-related menstrual and sex hormonal disturbances and the effect of exercise on bone mass and metabolism in female runners at various training levels. Two hundred and five premenopausal women (running 0-140 km a week) were recruited from a large population of female runners, who had responded to a questionnaire regarding exercise habits. Maximum oxygen uptake was determined by treadmill testing. Gynaecological status was assessed on entries in a menstrual calendar and by transvaginal ultrasonography; and sex hormonal status was measured three times with 10-day intervals. Bone mass was measured in the lumbar spine, proximal femurs and total body by dual energy x-ray absorptiometry, and in the forearm by single photon absorptiometry. Bone turnover was assessed by plasma osteocalcin, serum alkaline phosphatase, and urinary calcium and hydroxyproline. The results showed that sex hormonal disturbances were significantly related to training intensity. Compared with the normally active women, the baseline levels and fluctuations of oestradiol and progesterone in the elite runners were reduced by up to 25-44%, (0.01 < p < 0.05). The prevalence of amenorrhoea increased from 1% in the normally active to 11% in the elite runners. No statistically significant relation was found between running activity and bone mass or bone turnover. However, the group of amenorrhoeic runners had a 10% reduction in lumbar bone mass as compared to the normally menstruating runners (p < 0.05), but the bone turnover was similar.(ABSTRACT TRUNCATED AT 250 WORDS)