Plain language summary
Young female runners are more likely to have a low bone mass for their age. It is thought that this might be partly due to them using more energy (calories) than they consume. This study looked at the relationship between nutrition intake and biomarkers of bone turnover in young female runners. Participants were competitive cross-country runners, aged 14-17. The girls ate their usual diet and kept a food diary for a week, to allow the researchers to analyse their nutritional intakes. Runners that had an elevated bone turnover consumed significantly less calories and calcium than the runners with a normal bone turnover. They were also more likely to have a lower body mass, fewer menstrual cycles, lower oestrogen and vitamin D levels, lower BMI and lower bone mass. The authors concluded that nutritional support to increase energy and calcium intake, and vitamin D levels may improve bone growth in young female runners.
Abstract
BACKGROUND Female adolescent runners have an elevated prevalence of low bone mass for agemdashan outcome that may be partially due to inadequate energy intake. OBJECTIVE The objective was to evaluate diet, menstrual history, serum hormone concentrations, and bone mass in female adolescent runners with normal or abnormal bone turnover. DESIGN Thirty-nine cross-country runners (age: 15.7 plusmn 0.2 y) participated in the study, which included a 7-d dietary assessment with the use of a food record and daily 24-h dietary recalls; serum measures of insulin-like growth factor I, estradiol, leptin, parathyroid hormone, progesterone, triiodothyronine, 25-hydroxycholecalciferol, bone-specific alkaline phosphatase (BAP), and cross-linked C-telopeptides of type I collagen (CTX); an evaluation of height, weight, bone mass, and body composition with the use of dual-energy X-ray absorptiometry; and a questionnaire to assess menses and sports participation. Age- and sex-specific BAP and CTX concentrations of at least the 97th percentile and no greater than the third percentile, respectively, were considered abnormal. RESULTS All abnormal BAP and CTX concentrations fell within the elevated ( ge 97%) range. Runners with an elevated bone turnover (EBT) (n = 13) had a lower body mass, fewer menstrual cycles in the past year, lower estradiol and 25-hydroxycholecalciferol concentrations, and a higher prevalence of body mass index lt 10% for age, vitamin D insufficiency, amenorrhea, and low bone mass. Girls with EBT consumed less than the recommended amounts of energy and had a higher prevalence of consuming lt 1300 mg Ca than did those with normal bone turnover. CONCLUSIONS Runners with EBT had a profile consistent with energy deficiency. Nutritional support to increase energy, calcium intake, and 25-hydroxycholecalciferol concentrations may improve bone mineral accrual in young runners with EBT. This trial was registered at clinicaltrials.gov as NCT01059968.
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