Factors Associated With High-Risk and Low-Risk Bone Stress Injury in Female Runners: Implications for Risk Factor Stratification and Management.

Background: Bone stress injury (BSI) is a common overuse injury in active women. BSIs can be classified as high-risk (pelvis, sacrum, and femoral neck) or low-risk (tibia, fibula, and metatarsals). Risk factors for BSI include low energy availability, menstrual dysfunction, and poor bone health. Higher vertical load rates during running have been observed in women with a history of BSI. Purpose/Hypothesis: The purpose of this study was to characterize factors associated with BSI in a population of premenopausal women, comparing those with a history of high-risk or low-risk BSI with those with no history of BSI. It was hypothesized that women with a history of high-risk BSI would be more likely to exhibit lower bone mineral density (BMD) and related factors and less favorable bone microarchitecture compared with women with a history of low-risk BSI. In contrast, women with a history of low-risk BSI would have higher load rates. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Enrolled were 15 women with a history of high-risk BSI, 15 with a history of low-risk BSI, and 15 with no history of BSI. BMD for the whole body, hip, and spine was standardized using z scores on dual-energy x-ray absorptiometry. High-resolution peripheral quantitative computed tomography was used to quantify bone microarchitecture at the radius and distal tibia. Participants completed surveys characterizing factors that influence bone health-including sleep, menstrual history, and eating behaviors-utilizing the Eating Disorder Examination Questionnaire (EDE-Q). Each participant completed a biomechanical assessment using an instrumented treadmill to measure load rates before and after a run to exertion. Results: Women with a history of high-risk BSI had lower spine z scores than those with low-risk BSI (-1.04 ± 0.76 vs -0.01 ± 1.15; P < .05). Women with a history of high-risk BSI, compared with low-risk BSI and no BSI, had the highest EDE-Q subscores for Shape Concern (1.46 ± 1.28 vs 0.76 ± 0.78 and 0.43 ± 0.43) and Eating Concern (0.55 ± 0.75 vs 0.16 ± 0.38 and 0.11 ± 0.21), as well as the greatest difference between minimum and maximum weight at current height (11.3 ± 5.4 vs 7.7 ± 2.9 and 7.6 ± 3.3 kg) (P < .05 for all). Women with a history of high-risk BSI were more likely than those with no history of BSI to sleep <7 hours on average per night during the week (80% vs 33.3%; P < .05). The mean and instantaneous vertical load rates were not different between groups. Conclusion: Women with a history of high-risk BSI were more likely to exhibit risk factors for poor bone health, including lower BMD, while load rates did not distinguish women with a history of BSI.

Specific dietary practices in female athletes and their association with positive screening for disordered eating.

BACKGROUND: To determine if following specific diets was associated with reporting behaviors that are consistent with disordered eating compared to non-diet-adherent athletes. We hypothesized that athletes adhering to specific diets were more likely to report disordered eating than those not following a diet. METHODS: One thousand female athletes (15-30 years) completed a comprehensive survey about athletic health and wellness. Athletes were asked to specify their diet and completed 3 eating disorder screening tools: the Brief Eating Disorder in Athletes Questionnaire, the Eating Disorder Screen for Primary Care, and self-reported current or past history of eating disorder or disordered eating. Descriptive statistics were calculated for all study measures and chi-squared tests assessed relationships between athletes' dietary practices and their responses to eating disorder screening tools. Statistical significance was defined as p < 0.05. RESULTS: Two hundred thirty-four of 1000 female athletes reported adherence to specific diets. 69 of the 234 diet-adhering athletes (29.5%) were excluded due to medically-indicated dietary practices or vague dietary descriptions. Of the 165 diet-adherent athletes, 113 (68.5%) screened positively to ≥1 of the 3 eating disorder screening tools. Specifically, athletes practicing a low-carbohydrate diet were more likely to report disordered eating vs. athletes without dietary restrictions (80% vs. 41.8%; p < 0.0001). CONCLUSION: Specific diet adherence in female athletes may be associated with reporting behaviors that are consistent with disordered eating. Health practitioners should consider further questioning of athletes reporting specific diet adherence in order to enhance nutritional knowledge and help treat and prevent eating disorders or disordered eating.

Female athletes may follow special diets for various reasons including sociocultural practices, environmental concerns, or health and weight-management benefits. These practices may put them at risk for developing eating disorders, which peak during adolescence, and are more common among athletes. Eating disorders or disordered eating in athletes may lead to inadequate fueling or low energy availability and its subsequent health and performance-related complications, also known as Relative Energy Deficiency in Sport (RED-S). It may be difficult to detect eating disorders among athletes due to the secretive nature behind these behaviors. In addition, objective information such as low weight or body mass index (BMI) may not be reliable due to their increased muscle mass. The results of this study revealed that female athletes who reported practicing special diets, especially those who follow a low-carbohydrate diet may be associated with developing eating disorders compared to female athletes who did not report any dietary restrictions. These findings should prompt healthcare providers to evaluate these individuals further in order to enhance their nutritional knowledge and help treat and prevent consequences linked to eating disorders or disordered eating.

A Short-Term Ketogenic Diet Impairs Markers of Bone Health in Response to Exercise.

Objectives: To investigate diet-exercise interactions related to bone markers in elite endurance athletes after a 3.5-week ketogenic low-carbohydrate, high-fat (LCHF) diet and subsequent restoration of carbohydrate (CHO) feeding. Methods: World-class race walkers (25 male, 5 female) completed 3.5-weeks of energy-matched (220 kJ·kg·d-1) high CHO (HCHO; 8.6 g·kg·d-1 CHO, 2.1 g·kg·d-1 protein, 1.2 g·kg·d-1 fat) or LCHF (0.5 g·kg·d-1 CHO, 2.1 g·kg·d-1 protein, 75-80% of energy from fat) diet followed by acute CHO restoration. Serum markers of bone breakdown (cross-linked C-terminal telopeptide of type I collagen, CTX), formation (procollagen 1 N-terminal propeptide, P1NP) and metabolism (osteocalcin, OC) were assessed at rest (fasting and 2 h post meal) and after exercise (0 and 3 h) at Baseline, after the 3.5-week intervention (Adaptation) and after acute CHO feeding (Restoration). Results: After Adaptation, LCHF increased fasting CTX concentrations above Baseline (p = 0.007, Cohen's d = 0.69), while P1NP (p < 0.001, d = 0.99) and OC (p < 0.001, d = 1.39) levels decreased. Post-exercise, LCHF increased CTX concentrations above Baseline (p = 0.001, d = 1.67) and above HCHO (p < 0.001, d = 0.62), while P1NP (p < 0.001, d = 0.85) and OC concentrations decreased (p < 0.001, d = 0.99) during exercise. Exercise-related area under curve (AUC) for CTX was increased by LCHF after Adaptation (p = 0.001, d = 1.52), with decreases in P1NP (p < 0.001, d = 1.27) and OC (p < 0.001, d = 2.0). CHO restoration recovered post-exercise CTX and CTX exercise-related AUC, while concentrations and exercise-related AUC for P1NP and OC remained suppressed for LCHF (p = 1.000 compared to Adaptation). Conclusion: Markers of bone modeling/remodeling were impaired after short-term LCHF diet, and only a marker of resorption recovered after acute CHO restoration. Long-term studies of the effects of LCHF on bone health are warranted.

Linking big: the continuing promise of evolutionary synthesis.

Synthetic science promises an unparalleled ability to find new meaning in old data, extant results, or previously unconnected methods and concepts, but pursuing synthesis can be a difficult and risky endeavor. Our experience as biologists, informaticians, and educators at the National Evolutionary Synthesis Center has affirmed that synthesis can yield major insights, but also revealed that technological hurdles, prevailing academic culture, and general confusion about the nature of synthesis can hamper its progress. By presenting our view of what synthesis is, why it will continue to drive progress in evolutionary biology, and how to remove barriers to its progress, we provide a map to a future in which all scientists can engage productively in synthetic research.