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Evidence of energy deficiency, using doubly‐labeled water, among adolescent endurance runners (LB316)
Author(s) -
Barrack Michelle,
Nichols Jeanne,
Rauh Mitchell,
Van Loan Marta
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.lb316
Subject(s) - medicine , anthropometry , bone mineral , urine , energy expenditure , endocrinology , urine specific gravity , hormone , fat mass , body weight , physiology , zoology , physical therapy , osteoporosis , biology
Background: Inadequate energy intake has been hypothesized to partially contribute to runners’ low BMD levels. Purpose: To assess the nutritional adequacy of adolescent runners’ diets and identify relationships between runners’ energy status, menstrual function, relevant hormones, biomarkers of bone metabolism, and bone mass. Methods: Twelve adolescent runners (age 16.0 ± 0.3y) completed a 7‐d food log, daily 24‐hr recalls, and assessments of serum hormones, biomarkers of bone turnover, anthropometrics, menstrual function, sports participation, and training volume. Additionally, they underwent a doubly‐labeled water protocol. Runners provided a baseline urine sample and consumed body weight‐specific cocktails 0.12g·kg‐1 of 2H2O and 0.25g·kg‐1 of H218O. Follow‐up first‐void urine samples were collected on days 1, 3, 5, and 7. Results: Among the adolescent runners (BMI= 19.7 kg/m2), who ran 31.2 (±11.1) miles/wk, mean (SD) 7‐day energy intake and expenditure values were 2,213.3 (±374.1) kcal and 3,131.6 (±403.3) kcal, respectively. Thus, runners consumed 918.3 (±449.9) kcal less than expended. Current weekly running mileage was inversely related to body weight (r= ‐0.78, p= 0.003), BMI (r= ‐0.66, p=0.02), gynecological age (r= ‐0.58, p= 0.05),serum estradiol (r= ‐0.64, p= 0.02), spine BMD (r= ‐0.77, p= 0.004), spine BMC (r= ‐0.79, p= 0.002), and spine BMD Z‐score (r= ‐0.63, p= 0.03), but positively related to CTX (r= 0.62, p= 0.03),. Conclusion: Among the runners, energy expended was significantly higher than energy consumed. This energy deficit may have contributed to low BMD, as miles of running per week, a proxy of exercise energy expenditure, correlated with a marker of bone resorption, and was inversely related to body mass, menstrual variables, and bone mass.