Context Young amenorrheic athletes (AA) have lower bonemineral density (BMD) and an increased prevalence of fracture compared with eumenorrheic athletes (EA) and non-athletes. Trabecular morphology is a determinant of skeletal strength and may contribute to fracture risk. Objectives To determine the variation in trabecular morphology among AA, EA, and non-athletes and to determine the association of trabecular morphology with fracture among AA. Design and setting A cross-sectional study performed at an academic clinical research center. Participants 161 girls and young women aged 14–26 years (97 AA, 32 EA, and 32 non-athletes). Main outcome measure We measured volumetric BMD (vBMD) and skeletal microarchitecture using high-resolution peripheral quantitative computed tomography. We evaluated trabecular morphology (plate-like vs. rod-like), orientation, and connectivity by individual trabecula segmentation. Results At the non-weight-bearing distal radius, the groups did not differ for trabecular vBMD. However, plate-like trabecular bone volume fraction (pBV/TV) was lower in AA vs. EA (p = 0.03), as were plate number (p = 0.03) and connectivity (p = 0.03). At the weight-bearing distal tibia, trabecular vBMD was higher in athletes vs. non-athletes (p=0.05 for AA and p=0.009 for EA vs. non-athletes, respectively). pBV/TV was higher in athletes vs. non-athletes (p=0.04 AA and p=0.005 EA vs. non-athletes), as were axially-aligned trabeculae, plate number, and connectivity. Among AA, those with a history of recurrent stress fracture had lower pBV/TV, axially-aligned trabeculae, plate number, plate thickness, and connectivity at the distal radius. Conclusions Trabecular morphology and alignment differ among AA, EA, and non-athletes. These differences may be associated with increased fracture risk.

BackgroundThe effect of chronic exercise activity on brown adipose tissue (BAT) is not clear, with some studies showing positive and others showing negative associations. Chronic exercise is associated with increased resting energy expenditure (REE) secondary to increased lean mass and a probable increase in BAT. Many athletes are in a state of relative energy deficit suggested by lower fat mass and hypothalamic amenorrhea. States of severe energy deficit such as anorexia nervosa are associated with reduced BAT. There are no data regarding the impact of chronic exercise activity on BAT volume or activity in young women and it is unclear whether relative energy deficiency modifies the effects of exercise on BAT.PurposeWe assessed cold induced BAT volume and activity in young female athletes compared with non-athletes, and further evaluated associations of BAT with measures of REE, body composition and menstrual status.MethodsThe protocol was approved by our Institutional Review Board. Written informed consent was obtained from all participants prior to study initiation. This was a cross-sectional study of 24 women (16 athletes and8 non-athletes) between 18–25 years of age. Athletes were either oligo-amenorrheic (n = 8) or eumenorrheic (n = 8).We used PET/CT scans to determine cold induced BAT activity, VMAX Encore 29 metabolic cart to obtain measures of REE, and DXA for body composition.ResultsAthletes and non-athletes did not differ for age or BMI. Compared with non-athletes, athletes had lower percent body fat (p = 0.002), higher percent lean mass (p = 0.01) and trended higher in REE (p = 0.09). BAT volume and activity in athletes trended lower than in non-athletes (p = 0.06; p = 0.07, respectively). We found negative associations of BAT activity with duration of amenorrhea (r = -0.46, p = 0.02).BAT volume correlated inversely with lean mass (r = -0.46, p = 0.02), and positively with percent body fat, irisin and thyroid hormones.ConclusionsOur study shows a trend for lower BAT in young female athletes compared with non-athletes, and shows associations of brown fat with menstrual status and body composition. Brown fat may undergo adaptive reductions with increasing energy deficit.

Background Associations of bone mineral density (BMD) with specific food components, including dietary fiber and isoflavones (that have a negative association with serum estrogen), are unclear and need to be determined, particularly in a population more likely to consume large amounts of these nutrients (such as young athletes). Objective To determine dietary intake of specific food components in oligo-amenorrheic athletes (OA) compared to eumenorrheic athletes (EA) and non-athletes (NA), and associations of the dietary intake of these nutrients with lumbar spine BMD. Design and Subjects This cross-sectional study evaluated 68 OA, 24 EA, and 26 NA 14–23 years old. Measurements included four-day food records (assessed using Nutrient Data System for Research software), a DXA scan evaluating lumbar spine BMD and body composition, and hormone levels. Multivariate analysis was used to estimate associations of nutrients with lumbar spine BMD. Results Compared with EA and NA, OA had higher intake of fiber, phytic acid, and vegetable protein (p<0.0001 for all). Intake of isoflavones, genistein and daidzein, was higher in OA than NA (p=0.003 and 0.0002 respectively). OA had lower consumption of energy from saturated fatty acids (%SFA) than NA (p=0.002). After controlling for confounders such as body weight, menstrual status (indicative of estrogen status), calcium intake, and serum vitamin D (known BMD determinants), lumbar spine BMD Z-scores were inversely associated with dietary fiber [β coefficient (β)= −0.30; p=0.01], vegetable protein (β = −0.28, p=0.02), phytic acid (β = −0.27, p=0.02), genistein (β = −0.25, p=0.01), and daidzein (β = −0.24, p=0.01), and positively with %SFA (β =0.32, p=0.0006)]. Conclusions Compared to EA and NA, OA had a higher dietary intake of fiber, vegetable protein and phytic acid, which were inversely associated with lumbar spine BMD Z-scores. Further studies are needed to assess dietary recommendations for OA to optimize bone accrual.