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BACKGROUND Bone stress injury (BSI) in youth runners is clinically important during times of skeletal growth and is not well studied. OBJECTIVE To evaluate the prevalence, anatomical distribution, and factors associated with running-related BSI in boy and girl middle school runners. DESIGN Retrospective cross-sectional study. SETTING Online survey distributed to middle school runners. METHODS Survey evaluated BSI history, age, grade, height, weight, eating behaviors, menstrual function, exercise training, and other health characteristics. MAIN OUTCOME MEASUREMENTS Prevalence and characteristics associated with history of BSI, stratified by cortical-rich (eg, tibia) and trabecular-rich (pelvis and femoral neck) locations. PARTICIPANTS 2107 runners (n = 1250 boys, n = 857 girls), age 13.2 ± 0.9 years. RESULTS One hundred five (4.7%) runners reported a history of 132 BSIs, with higher prevalence in girls than boys (6.7% vs 3.8%, p = .004). The most common location was the tibia (n = 51). Most trabecular-rich BSIs (n = 16, 94% total) were sustained by girls (pelvis: n = 6; femoral neck: n = 6; sacrum: n = 4). In girls, consuming

Optimal nutrition is an important aspect of an athlete’s preparation to achieve optimal health and performance. While general concepts about micro- and macronutrients and timing of food and fluids are addressed in sports science, rarely are the specific effects of women’s physiology on energy and fluid needs highly considered in research or clinical practice. Women differ from men not only in size, but in body composition and hormonal milieu, and also differ from one another. Their monthly hormonal cycles, with fluctuations in estrogen and progesterone, have varying effects on metabolism and fluid retention. Such cycles can change from month to month, can be suppressed with exogenous hormones, and may even be manipulated to capitalize on ideal timing for performance. But before such physiology can be manipulated, its relationship with nutrition and performance must be understood. This review will address general concepts regarding substrate metabolism in women versus men, common menstrual patterns of female athletes, nutrient and hydration needs during different phases of the menstrual cycle, and health and performance issues related to menstrual cycle disruption. We will discuss up-to-date recommendations for fueling female athletes, describe areas that require further exploration, and address methodological considerations to inform future work in this important area.

Understanding the prevalence and factors associated with running-related injuries in middle school runners may guide injury prevention.To determine the prevalence of running-related injuries and describe factors related to a history of injury.Retrospective cross-sectional study.Survey distributed online to middle school runners.Participants completed a web-based survey regarding prior running-related injuries, training, sleep, diet, and sport participation.Prevalence and characteristics differentiating girls and boys with and without running-related injury history adjusted for age.Youth runners (total: 2113, average age, 13.2 years; boys: n = 1255, girls: n = 858).Running-related injuries were more prevalent in girls (56% vs. 50%, p = .01). Ankle sprain was the most common injury (girls: 22.5%, boys: 21.6%), followed by patellofemoral pain (20.4% vs. 7.8%) and shin splints (13.6% vs. 5.9%); both were more prevalent in girls (p .001). Boys more frequently reported plantar fasciitis (5.6% vs. 3.3%, p = .01), iliotibial band syndrome (4.1% vs. 1.4%, p = .001) and Osgood-Schlatter disease (3.8% vs. 1.2%, p = .001). Runners with history of running-related injuries were older, ran greater average weekly mileage, ran faster, had fewer average hours of sleep on weekends, skipped more meals, missed breakfast, and consumed less milk (all p .05). Girls with history of running-related injuries reported higher dietary restraint scores, later age of menarche, more menstrual cycle disturbances, and higher likelihood of following vegetarian diets and an eating disorder diagnosis (all p .05). Runners with no history of running-related injuries were more likely to have participated in ≥2 years of soccer or basketball (p .001).Most middle school runners reported a history of running-related injuries and certain injuries differing by gender. Modifiable factors with the greatest association with running-related injuries included training volume, dietary restraint, skipping meals, and less sleep. Sport sampling, including participation in ball sports, may reduce running-related injury risk in this population.

Bone stress injuries (BSIs) occur in up to 20% of runners and military recruits and those with a history of BSI have a 5-fold higher risk for a subsequent BSI. Yet, little is known about prior training, menstrual status and bone structure in runners who experience multiple BSIs. PURPOSE: To determine differences in health and physical activity history, bone density, microarchitecture, and strength among female athletes with a history of multiple BSI, athletes with ≤1 BSI, and non-athletes. METHODS: We enrolled 101 women (ages 18–32 years) for this cross-sectional study: non-athlete controls (n=17) and athletes with a history of ≥ 3 BSIs (n=21) or ≤1 BSI (n=63). We collected subjects’ health and training history and measured bone microarchitecture of the distal tibia via high-resolution peripheral quantitative computed tomography (HR-pQCT) and areal bone mineral density (aBMD) of the hip and spine by dual-energy X-ray absorptiometry (DXA). RESULTS: Groups did not differ according to age, BMI, age at menarche, aBMD, or tibial bone microarchitecture. Women with multiple BSIs had a higher prevalence of primary and secondary amenorrhea (p

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, Plain English summary 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.

PurposeTo synthesise evidence on low back pain (LBP) in adult rowers and to create a consensus statement to inform clinical practice.MethodsThere were four synthesis steps that informed the consensus statement. In step one, seven expert clinicians and researchers established the scope of the consensus statement and conducted a survey of experienced and expert clinicians to explore current practice. In step two, working groups examined current evidence relating to key scope questions and summarised key issues. In step three, we synthesised evidence for each group and used a modified Delphi process to aid in the creation of the overall consensus statements. Finally, in step four, we combined information from step three with the findings of the clinician survey (and with athlete and coach input) to produce recommendations for clinical practice.ResultsThe scope of the consensus statement included epidemiology; biomechanics; management; the athlete’s voice and clinical expertise. Prevention and management of LBP in rowers should include education on risk factors, rowing biomechanics and training load. If treatment is needed, non-invasive management, including early unloading from aggravating activities, effective pain control and exercise therapy should be considered. Fitness should be maintained with load management and progression to full training and competition. The role of surgery is unclear. Management should be athlete focused and a culture of openness within the team encouraged.ConclusionRecommendations are based on current evidence and consensus and aligned with international LBP guidelines in non-athletic populations, but with advice aimed specifically at rowers. We recommend that research in relation to all aspects of prevention and management of LBP in rowers be intensified.

A 16.5-year-old, distance runner, female gender-assigned at birth, who identifies as male, presented with menstrual dysfunction and impaired athletic performance. The cause of the menstrual dysfunction and decreased athletic performance was identified as inadequate energy availability, largely motivated by a desired avoidance of menstruation and further development of secondary sex characteristics. The patient achieved significant weight gain (4.75 kg) in the year after presentation and resumed normal menses. When evaluating and treating transgender athletes for menstrual dysfunction and inadequate energy availability, psychological motivators related to the complex interplay between gender identity, disordered eating, and athletic performance must be addressed.

Female athletes are participating in collision sports in greater numbers than previously. The overall incidence of concussion is known to be higher in female athletes than in male athletes participating in similar sports. Evidence suggests anatomic, biomechanical, and biochemical etiologies behind this sex disparity. Future research on female athletes is needed for further guidance on prevention and management of concussion in girls and women.

Background: Bone stress injuries (BSIs) occur in up to 20% of runners and military personnel. Typically, after a period of unloading and gradual return to weightbearing activities, athletes return to unrestricted sports participation or military duty approximately 4 to 14 weeks after a BSI diagnosis, depending on the injury location and severity. However, the time course of the recovery of the bone’s mechanical competence is not well-characterized, and reinjury rates are high. Purpose: To assess the bone microarchitecture and volumetric bone mineral density (vBMD) over 12 months after a tibial BSI diagnosis. Study Design: Case-control study; Level of evidence, 3. Methods: We enrolled 30 female athletes from the local community (aged 18-35 years) with a tibial BSI (grade ≥2 of 4 on magnetic resonance imaging) for this prospective observational study. Participants completed a baseline visit within 3 weeks of the diagnosis. At baseline and 6, 12, 24, and 52 weeks after the BSI diagnosis, we collected high-resolution peripheral quantitative computed tomography scans of the ultradistal tibia (4% of tibial length) of the injured and uninjured legs as well as pain and physical activity assessment findings. Results: From baseline to 12 weeks after the diagnosis, total, trabecular, and cortical vBMD declined by 0.58% to 0.94% ( P < .05 for all) in the injured leg. Total and trabecular vBMD also declined by 0.61% and 0.67%, respectively, in the uninjured leg ( P < .05 for both). At 24 weeks, mean values for all bone parameters were nearly equivalent to baseline values, and by 52 weeks, several mean values had surpassed baseline values. Of the 30 participants, 10 incurred a subsequent BSI during the course of the study, and 1 of these 10 incurred 2 subsequent BSIs. Participants who suffered an additional BSI were younger and had a later age of menarche, a greater incidence of previous fractures, and lower serum parathyroid hormone levels ( P < .05 for all). Conclusion: Bone density declined in both the injured and the uninjured legs and, on average, did not return to baseline for 3 to 6 months after a tibial BSI diagnosis. The observed time to the recovery of baseline vBMD, coupled with the high rate of recurrent BSIs, suggests that improved return-to-sports and military duty guidelines may be in order.

For many female athletes, serious pursuit of athletics occurs nearly at the same age as menarche and activation of the hypothalamic–pituitary–gonadal (HPG) axis. For much of their athletic careers, these athletes are exposed to normal physiologic changes that accompany their menstrual cycles — which can affect their comfort during training and competition — and the regular underlying hormonal shifts throughout the menstrual cycle. Different hormone levels between women and men have been hypothesized to play a role in injury risk, particularly anterior cruciate ligament (ACL) tears. This review serves as a primer on the HPG axis for athletes, coaches, caretakers, and physicians to understand basic physiology of the HPG axis, injuries affected by the HPG axis, purposeful manipulation of the HPG axis, and identification of improper function of the HPG axis.

Low energy availability (EA), caused by insufficient caloric intake for daily energy expenditure, is detrimental to an athlete's performance and long-term health. Male and female athletes are at considerable risk for low EA and relative energy deficiency in sport because of intense training regimens, potential lack of nutrition education, and pressures associated with “ideal” body type for performance. This review summarizes the endocrine and metabolic changes observed in athletes with low EA with an emphasis on the most recent research findings. While awareness of relative energy deficiency in sport has significantly increased, further investigation is needed in the advancement of a sensitive diagnostic tool across populations.

Context Female endurance athletes exhibit an increased risk of the female athlete triad (Triad) and relative energy deficiency in sport (RED-S). The triad and RED-S are conditions that involve the health and performance consequences of low energy availability. Few authors of studies to date have assessed the knowledge that athletes, coaches, and athletic trainers (ATs) have regarding the Triad or RED-S. Proper education has been shown to be effective in increasing knowledge of sports medicine concerns for athletes, yet no known continuing education programs for the Triad or RED-S exist at collegiate institutions. Objective To assess the knowledge, confidence, and educational impact of identifying, screening, treating, and preventing the Triad or RED-S. Design Cross-sectional study. Setting An evidence-based online survey was developed and administered via Qualtrics. Patients or Other Participants Female collegiate cross-country athletes (n = 275, age = 20 ± 1 years), collegiate cross-country coaches (n = 55, age = 34 ± 9 years), and ATs working with cross-country teams (n = 30, age = 36 ± 11 years). Main Outcome Measure(s) Knowledge, confidence, and educational impact scores were assessed among groups using analysis of variance. Independent t tests were calculated to determine differences in impact scores between people who had or had not received education on the topic. Results Female cross-country athletes' total knowledge, confidence, and educational impact scores (mean scores = 25.00 ± 5.27, 95.42 ± 28.83, and 18.81 ± 7.05, respectively) were different from those of coaches (mean scores = 26.92 ± 5.02, 111.35 ± 24.14, and 22.41 ± 6.33, respectively) and ATs (mean scores = 28.66 ± 4.02, 117.67 ± 22.53, and 23.93 ± 5.69, respectively; P < .05). Conclusions Knowledge, confidence, and educational impact scores regarding Triad or RED-S were lowest in female cross-country athletes and highest in ATs. These findings support the call for education, which should be regarded as the primary tool for increasing knowledge, to improve the prevention and treatment of the Triad or RED-S.

OBJECTIVES: To determine whether serum 25-hydroxy vitamin D (25-OH D) levels are associated with bone microarchitecture and strength in a multi-racial cohort of young adults. We also determined if race and calcium intake modified these associations. METHODS: This cross-sectional study included 176 young adults who identified as Asian, Black, or White (50% women). High-resolution peripheral quantitative computed tomography (HR-pQCT, 2nd generation) scans of the distal radius and tibia were used to assess bone microarchitecture and strength by micro-finite element analysis. We measured 25-OH D levels (ng/mL, immunoassay), dietary intake (Block's Food Frequency Questionnaire), and physical activity (questionnaire). We used linear regression to estimate the association between 25-OH D and standardized bone measures, adjusting for race, sex, age, weight, height, calcium intake, and physical activity. The interactions of 25-OH D with race and calcium intake (mg/d) were tested and models were stratified for significant interactions (P

ObjectiveTo summarise the evidence for non-pharmacological management of low back pain (LBP) in athletes, a common problem in sport that can negatively impact performance and contribute to early retirement.Data sourcesFive databases (EMBASE, Medline, CINAHL, Web of Science, Scopus) were searched from inception to September 2020. The main outcomes of interest were pain, disability and return to sport (RTS).ResultsAmong 1629 references, 14 randomised controlled trials (RCTs) involving 541 athletes were included. The trials had biases across multiple domains including performance, attrition and reporting. Treatments included exercise, biomechanical modifications and manual therapy. There were no trials evaluating the efficacy of surgery or injections. Exercise was the most frequently investigated treatment; no RTS data were reported for any exercise intervention. There was a reduction in pain and disability reported after all treatments.ConclusionsWhile several treatments for LBP in athletes improved pain and function, it was unclear what the most effective treatments were, and for whom. Exercise approaches generally reduced pain and improved function in athletes with LBP, but the effect on RTS is unknown. No conclusions regarding the value of manual therapy (massage, spinal manipulation) or biomechanical modifications alone could be drawn because of insufficient evidence. High-quality RCTs are urgently needed to determine the effect of commonly used interventions in treating LBP in athletes.

BACKGROUND: Despite their higher areal bone mineral density (aBMD), adolescents with obesity (OB) have an increase in fracture risk, particularly of the extremities, compared with normal-weight controls. Whereas bone parameters that increase fracture risk are well characterized in anorexia nervosa (AN), the other end of nutritional spectrum, these data are lacking in adolescents with obesity. OBJECTIVE: Our objective was to compare bone parameters in adolescent girls across the nutritional spectrum, to determine whether suboptimal bone adaptation to increased body weight may explain the increased fracture risk in OB. METHODS: We assessed bone endpoints in 153 adolescent girls 14-21 years old: 50 OB, 48 controls and 55 AN. We used (i) DXA to assess aBMD at the lumbar spine, proximal femur and whole body, and body composition, (ii) high resolution peripheral quantitative CT (HRpQCT) to assess bone geometry, microarchitecture and volumetric BMD (vBMD), and (iii) finite element analysis to assess failure load (a strength estimate) at the distal radius and tibia. All aBMD, microarchitecture and FEA analyses were controlled for age and race. RESULTS: Groups did not differ for age or height. Areal BMD Z-scores at all sites were highest in OB, intermediate in controls and lowest in AN (p

BACKGROUND: Mechanical loading improves bone mineral density (BMD) and strength while decreasing fracture risk. Cross-sectional studies show that exercise advantage is lost in oligo-amenorrheic athletes (OA). Longitudinal studies examining the opposing effects of exercise and hypogonadism on bone are lacking in adolescents/young adults. OBJECTIVE: Evaluate differences in bone accrual over 12 months in OA, eumenorrheic athletes (EA) and non-athletes (NA). We hypothesized that bone accrual would be lower in OA than EA and NA, with differences most pronounced at non-weight bearing trabecular sites. METHODS: 27 OA, 29 EA, and 22 NA, 14-25 years old, completed 12-months of the prospective study. Athletes were weight-bearing endurance athletes. Subjects were assessed for areal BMD and bone mineral content (BMC) using DXA at the femoral neck, total hip, lumbar spine and whole body (WB). Failure load (a strength estimate) at the distal radius and tibia was assessed using microfinite element analysis of data obtained via high resolution peripheral quantitative computed tomography (HRpQCT). The primary analysis was a comparison of changes in areal BMD, BMC, and failure load across groups over 12-months at the respective sites. RESULTS: Groups did not differ for baseline age, height or BMI. Percent body fat was lower in both OA and EA compared to NA. OA attained menarche later than EA and NA. Over the follow-up period, OA gained 1.9±2.7 kg of weight compared to 0.5±2.4 kg and 0.8±2.3 kg in EA and NA respectively (p=0.09); 39% of OA resumed menses. Changes in BMD, BMD Z-scores, and tibial failure load over 12-months did not differ among groups. At follow up, EA had higher femoral neck, hip and WB BMD Z-scores than NA, and higher hip BMD Z-scores than OA (p

The purpose of this case series was to evaluate the presence of low Energy Availability (EA) and its impact on components of Relative Energy Deficiency in Sport (RED-S) in a population of female collegiate runners. Seven female NCAA Division I athletes (age: 22.3 ± 1.5 yrs; height: 169.7 ± 5.7 cm; weight: 58.3 ± 4.1 kg) were tracked from August until February, covering the beginning (Pre XC), end (Post XC) of their competitive cross country season, and beginning of the following track season (Pre Track). The athletes were assessed for female athlete triad (Triad) risk, energy availability, body composition, resting metabolic rate (RMR), nutritional intake, and blood markers (including vitamin D, ferritin, and triiodothyronine (T3)). From Pre XC to Post XC there were no significant differences in body mass, fat free mass or body fat percentage. At Pre XC, mean EA was 31.6 ± 13.3 kcal/kg FFM∙d-1. From Post XC to Pre Track, there was a significant increase in body mass (59.1 ± 5.1 to 60.6 ± 5.7 kg, p-1, pvs 39.5 ± 12.2 ng·mL-1, p=0.047,d=-0.4), and a significant increase from Post XC to Pre Track (39.5 ± 12.2 vs. 48.1 ± 10.4 ng·mL-1, p=0.014,d=0.75). For ferritin, there was a trend towards a decrease from Pre XC to Post XC (24.2 ± 13.2 vs. 15.7 ± 8.8 ng·mL-1, p=0.07, d=-0.75), as well as a trend toward an increase from Post XC to Pre Track (15.7 ± 8.8 vs. 34.1 ± 18.0 ng·mL-1, p=0.08, d=1.3). No differences in T3 were observed across time points. Average Triad risk score was 2.3 ± 1.4. Notably, 5 of 7 athletes met criteria for moderate risk. Despite many athletes meeting criteria for low EA and having elevated Triad risk assessment scores, most were able to maintain body mass and RMR. One athlete suffered severe performance decline and a reduced RMR. Surprisingly, she was the only athlete above the recommended value for ferritin. Following increased nutritional intake and reduced training volume, her performance and RMR recovered. Changes in body mass and body composition were not indicative of the presence of other concerns associated with RED-S. This exploratory work serves as a guide for future, larger studies for tracking athletes, using RMR and nutritional biomarkers to assess RED-S.

In BJSM , Gabel and colleagues in their paper ‘Pre-flight Exercise and Bone Metabolism Predict Unloading-Induced Bone Loss due to Spaceflight’ study skeletal health in a unique population of ‘occupational athletes’: astronauts.1 Astronauts frequently experience cardiovascular deconditioning, immune suppression, balance disorders, strength deficits and bone loss as a result of space travel.2 After more than 50 years of space missions, various contributors to bone loss in astronauts have been postulated—microgravity, radiation, stress, metabolic disruption and altered calcium homeostasis all likely play a role.3 Using high-resolution three-dimensional imaging (HR-pQCT), Gabel et al report declines in bone mineral density (BMD), bone microstructure and strength at the distal tibia, although minimal changes at the distal radius.1 Their findings are broadly similar to prior reports, revealing an average rate of bone decline nearly 10-fold higher than that seen in postmenopausal women, although with remarkable interindividual variability seen in these astronauts.4 Notably, their analyses bring several new insights to our understanding of unloading-induced bone loss. For spaceflight of 3.5–7 months, mission time predicted tibial BMD loss linearly, with accelerated trabecular bone loss in longer flights.1 …

Until recently, there has been less demand for and interest in female-specific sport and exercise science data. As a result, the vast majority of high-quality sport and exercise science data have been derived from studies with men as participants, which reduces the application of these data due to the known physiological differences between the sexes, specifically with regard to reproductive endocrinology. Furthermore, a shortage of specialist knowledge on female physiology in the sport science community, coupled with a reluctance to effectively adapt experimental designs to incorporate female-specific considerations, such as the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause, has slowed the pursuit of knowledge in this field of research. In addition, a lack of agreement on the terminology and methodological approaches (i.e., gold-standard techniques) used within this research area has further hindered the ability of researchers to adequately develop evidenced-based guidelines for female exercisers. The purpose of this paper was to highlight the specific considerations needed when employing women (i.e., from athletes to non-athletes) as participants in sport and exercise science-based research. These considerations relate to participant selection criteria and adaptations for experimental design and address the diversity and complexities associated with female reproductive endocrinology across the lifespan. This statement intends to promote an increase in the inclusion of women as participants in studies related to sport and exercise science and an enhanced execution of these studies resulting in more high-quality female-specific data.

Context Low energy availability causes disruption of hypothalamic gonadotropin-releasing hormone secretion leading to functional hypothalamic amenorrhea (FHA) and hypoestrogenism, which in turn contributes to decreased bone mineral density (BMD) and increased bone marrow adipose tissue (MAT). Transdermal estradiol administration in physiologic doses increases BMD in adolescents and adults with FHA. However, the impact of estrogen replacement on MAT in relation to changes in BMD has not been studied in adolescents and young adults. We hypothesized that physiologic estrogen replacement would lead to decreases in MAT, associated with increases in BMD. Methods and materials We studied 15 adolescent and young adult females with FHA (14–25 years). All participants received a17β- estradiol transdermal patch at a dose of 0.1 mg/day (applied twice weekly) for 12 months. Participants also received cyclic progestin for 10–12 days each month. We quantified MAT (lipid/water ratio) of the fourth lumbar (L4) vertebral body and femoral diaphysis by single proton (1H)-magnetic resonance spectroscopy, and compartmental volumetric BMD of the distal radius and tibia using high-resolution peripheral quantitative computed tomography. Results Transdermal estradiol therapy over 12 months resulted in a decrease in MAT at the lumbar (L4) vertebra from 0.92 ± 0.55 at baseline to 0.63 ± 0.29 at 12-months (p = 0.008), and an increase in radial and tibial cortical vBMD (p = 0.006, p = 0.0003). Changes in L4 MAT trended to be inversely associated with changes in radial cortical vBMD (rho = −0.47, p = 0.08). Conclusion We show that in adolescent and young adult girls with FHA, MAT decreases following transdermal estrogen therapy and these changes are associated with increased cortical vBMD.

Oligoamenorrheic athletes (OAs) have lower bone mineral density (BMD) and greater impairment of bone microarchitecture, and therefore higher fracture rates compared to eumenorrheic athletes. Although improvements in areal BMD (aBMD; measured by dual-energy X-ray absorptiometry) in OAs have been demonstrated with transdermal estrogen treatment, effects of such treatment on bone microarchitecture are unknown. Here we explore effects of transdermal versus oral estrogen versus no estrogen on bone microarchitecture in OA. Seventy-five OAs (ages 14 to 25 years) were randomized to (i) a 100-μg 17β-estradiol transdermal patch (PATCH) administered continuously with 200 mg cyclic oral micronized progesterone; (ii) a combined 30 μg ethinyl estradiol and 0.15 mg desogestrel pill (PILL); or (iii) no estrogen/progesterone (NONE) and were followed for 12 months. Calcium (≥1200 mg) and vitamin D (800 IU) supplements were provided to all. Bone microarchitecture was assessed using high-resolution peripheral quantitative CT at the distal tibia and radius at baseline and 1 year. At baseline, randomization groups did not differ by age, body mass index, percent body fat, duration of amenorrhea, vitamin D levels, BMD, or bone microarchitecture measurements. After 1 year of treatment, at the distal tibia there were significantly greater increases in total and trabecular volumetric BMD (vBMD), cortical area and thickness, and trabecular number in the PATCH versus PILL groups. Trabecular area decreased significantly in the PATCH group versus the PILL and NONE groups. Less robust differences between groups were seen at the distal radius, where percent change in cortical area and thickness was significantly greater in the PATCH versus PILL and NONE groups, and changes in cortical vBMD were significantly greater in the PATCH versus PILL groups. In conclusion, in young OAs, bone structural parameters show greater improvement after 1 year of treatment with transdermal 17β-estradiol versus ethinyl estradiol-containing pills, particularly at the tibia. © 2019 American Society for Bone and Mineral Research.

ObjectivesThe menstrual cycle can affect sports participation and exercise performance. There are very few data on specific menstrual cycle symptoms (symptoms during various phases of the cycle, not only during menstruation) experienced by exercising women. We aimed to characterise the most common symptoms, as well as the number and frequency of symptoms, and evaluate whether menstrual cycle symptoms are associated with sporting outcomes.Methods6812 adult women of reproductive age (mean age: 38.3 (8.7) years) who were not using combined hormonal contraception were recruited via the Strava exercise app user database and completed a 39-part survey. Respondents were from seven geographical areas, and the questions were translated and localised to each region (Brazil, n=892; France, n=1355; Germany, n=839; Spain, n=834; UK and Ireland, n=1350; and USA, n=1542). The survey captured exercise behaviours, current menstrual status, presence and frequency of menstrual cycle symptoms, medication use for symptoms, perceived effects of the menstrual cycle on exercise and work behaviours, and history of hormonal contraception use. We propose a novel Menstrual Symptom index (MSi) based on the presence and frequency of 18 commonly reported symptoms (range 0–54, where 54 would correspond to all 18 symptoms each occurring very frequently).ResultsThe most prevalent menstrual cycle symptoms were mood changes/anxiety (90.6%), tiredness/fatigue (86.2%), stomach cramps (84.2%) and breast pain/tenderness (83.1%). After controlling for body mass index, training volume and age, the MSi was associated with a greater likelihood of missing or changing training (OR=1.09 (CI 1.08 to 1.10); p≤0.05), missing a sporting event/competition (OR=1.07 (CI 1.06 to 1.08); p≤0.05), absenteeism from work/academia (OR=1.08 (CI 1.07 to 1.09); p≤0.05) and use of pain medication (OR=1.09 (CI 1.08 to 1.09); p≤0.05).ConclusionMenstrual cycle symptoms are very common in exercising women, and women report that these symptoms compromise their exercise participation and work capacity. The MSi needs to be formally validated (psychometrics); at present, it provides an easy way to quantify the frequency of menstrual cycle symptoms.

Summary Introduction Relative Energy Deficiency in Sport (RED-S) is a clinical syndrome that includes the many complex health and performance consequences of low energy availability (EA) in athletes, when there is insufficient caloric intake to meet exercise-related energy expenditure and to support basic physiologic functions. There is a high prevalence of urinary incontinence (UI) in female athletes and it is more common in female athletes than non-athletes. The objective of this study was to determine if low EA is associated with UI in a population of adolescent and young adult female athletes and to evaluate for an association between sport categories and UI. Material and methods 1000 nulliparous female patients, ages 15–30 years, presenting to a sports medicine subspecialty clinic, provided informed consent/assent to participate in a cross-sectional study involving a comprehensive survey, anthropomorphic measurements, and medical record review. Low EA was defined as meeting ≥1 criterion: self-reported history of eating disorder/disordered eating (ED/DE), and/or a high score on the Brief Eating Disorder in Athletes Questionnaire (BEDA-Q), and/or a high score on the Eating Disorder Screen for Primary Care (ESP). UI was assessed using questions adapted from the International Consultation on Incontinence-Urinary Incontinence Short Form (ICIQ-UI-SF), questions regarding timing of UI onset/duration, and a binary question regarding UI during sport activities. A total of 36 sport types were included in the survey and sub-divided into categories. Results and discussion Of the 1000 female athletes surveyed, 165 (16.5%) reported a history of experiencing UI during athletic activities. ICIQ- UI-SF responses indicated that 14% (137/1000) of the cohort experienced slight incontinence, 4% (35/1000) moderate incontinence, and 2 athletes experienced severe incontinence. There was a significant difference between UI categories in age (p = 0.01), low EA (p Conclusions UI during athletic activities is a common problem among nulliparous adolescent and young adult female athletes, occurring in 16.5% of female athletes surveyed. UI was significantly associated with low EA across all sport categories. Sport type was significantly associated with UI, with the highest impact sport group demonstrating a higher prevalence and symptom severity compared to other sport categories. Summary Table . Characteristics of Female Athletes with Urinary Incontinence Entire cohort N = 1000 Athletes with Urinary incontinence n = 165 (16.5%) P-value Freq. (%) Freq. (%) Low energy availability 473 (47%) 99 (20.9%) Menstrual dysfunction 449 (45%) 80 (17.8%) 0.31 Sport category: High impact 49 (5%) 18 (36.7%) Ball/field 356 (36%) 46 (12.9%) Non-weightbearing endurance 60 (6%) 6 (10.0%) Aesthetic 173 (17%) 25 (14.5%) Resistance/power 106 (11%) 23 (21.7%) Running 222 (22%) 44 (19.8%) Technical 34 (3%) 3 (8.8%)

Recently, Koltun et al. (2019) published a comparison of the risk assessment tools and return to play (RTP) guidelines developed by the Female Athlete Triad Coalition (Triad CRA; De Souza, Nattiv, ...

Bone (re)modeling markers can help determine how the bone responds to different types, intensities, and durations of exercise. They also might help predict those at risk of bone injury. We synthesized evidence on the acute and chronic bone metabolic responses to exercise, along with how nutritional factors can moderate this response. Recommendations to optimize future research efforts are made.

Bone stress injuries (BSIs) are an overuse form of injury resulting from strain in the setting of repetitive loading. A key component of BSI management is the identification and modification of underlying risk factors for BSI, which may include multiple biomechanical and/or biological factors. Biological risk factors for BSI may be both innate and acquired. Appropriate metabolic workup for runners with BSI starts with a detailed history and physical exam with a focus on features that may relate to bone health risk factors. Based on the clinical presentation, diagnostic imaging including radiographs, MR, and DXA scan may be considered. Laboratory evaluation may be considered to evaluate for potential underlying medical etiologies and/or associated comorbidities. Ultimately, management should be interdisciplinary and patient-centered, focused not only on resolution of an athlete's current BSI but, importantly, risk factor reduction and reinjury prevention in the setting of an athlete's return to running. This chapter is the second in this book, pertaining to BSI. Its focus is on factors affecting bone health and metabolic evaluation of those runners with impaired bone health that present with BSI.

In 2014, the International Olympic Committee (IOC) released a consensus statement introducing the term relative energy deficiency in sport (RED-S). RED-S refers to the various potential health and performance consequences of inadequate energy availability in the athlete. The RED-S concept expands upon the well-established female athlete triad and emphasizes that low EA can affect women and men. In this chapter, we briefly describe the RED-S health and performance models and then specifically focus on the endocrine implications of RED-S, including what are described as “menstrual function,” “bone health,” “metabolic,” and “endocrine” effects of RED-S.

Whole-bone analyses can obscure regional heterogeneities in bone characteristics. Quantifying these heterogeneities might improve our understanding of the etiology of injuries, such as lower-extremity stress fractures. Here, we performed regional analyses of high-resolution peripheral quantitative computed tomography images of the ultradistal tibia in young, healthy subjects (age range, 18 to 30 years). We quantified bone characteristics across four regional sectors of the tibia for the following datasets: white women (n = 50), black women (n = 51), white men (n = 50), black men (n = 34), and all subjects (n = 185). After controlling for potentially confounding variables, we observed statistically significant variations in most of the characteristics across sectors (p 0.05). Most of the bone characteristics followed a similar trend for all datasets but with different magnitudes. Regardless of race or sex, the anterior sector had the lowest trabecular and total volumetric bone mineral density and highest trabecular separation (p 0.001), while cortical thickness was lowest in the medial sector (p 0.05). Accordingly, the anterior sector also had the lowest elastic modulus in the anterior-posterior and superior-inferior directions (p 0.001). In all sectors, the mean anisotropy was ~3, suggesting cross-sector similarity in the ratios of loading in these directions. In addition, the bone characteristics from regional and whole-bone analyses differed in all datasets (p 0.05). Our findings on the heterogeneous nature of bone microarchitecture in the ultradistal tibia may reflect an adaptation of the bone to habitual loading conditions.

In 2014, the International Olympic Committee (IOC) published a consensus statement entitled “Beyond the Female Athlete Triad: Relative Energy Deficiency in Sport (RED-S)”. The syndrome of RED-S refers to: “impaired physiological functioning caused by relative energy deficiency, and includes but is not limited to impairments of metabolic rate, menstrual function, bone health, immunity, protein synthesis, and cardiovascular health.”

Low energy availability (EA) is suspected to be the underlying cause of both the Female Athlete Triad and the more recently defined syndrome, Relative Energy Deficiency in Sport (RED-S). The International Olympic Committee (IOC) defined RED-S as a syndrome of health and performance impairments resulting from an energy deficit. While the importance of adequate EA is generally accepted, few studies have attempted to understand whether low EA is associated with the health and performance consequences posited by the IOC.ObjectiveThe purpose of this cross-sectional study was to examine the association of low EA with RED-S health and performance consequences in a large clinical population of female athletes.MethodsOne thousand female athletes (15–30 years) completed an online questionnaire and were classified as having low or adequate EA. The associations between low EA and the health and performance factors listed in the RED-S models were evaluated using chi-squared test and the odds ratios were evaluated using binomial logistic regression (pResultsAthletes with low EA were more likely to be classified as having increased risk of menstrual dysfunction, poor bone health, metabolic issues, haematological detriments, psychological disorders, cardiovascular impairment and gastrointestinal dysfunction than those with adequate EA. Performance variables associated with low EA included decreased training response, impaired judgement, decreased coordination, decreased concentration, irritability, depression and decreased endurance performance.ConclusionThese findings demonstrate that low EA measured using self-report questionnaires is strongly associated with many health and performance consequences proposed by the RED-S models.

OBJECTIVE: We have reported low bone mineral density (BMD), impaired bone structure, and increased fracture risk in participants with anorexia nervosa (AN) and normal-weight oligoamenorrheic athletes (OAs). However, data directly comparing compartment-specific bone parameters in participants with AN, OAs, and controls are lacking. DESIGN: A total of 468 female participants 14 to 21.9 years old were included: 269 with AN, 104 OAs, and 95 normal-weight eumenorrheic controls. Dual-energy x-ray absorptiometry was used to assess areal BMD (aBMD) of the whole body less head (WBLH), spine, and hip. High-resolution peripheral quantitative computed tomography was used to assess volumetric BMD (vBMD), bone geometry, and structure at the non–weight-bearing distal radius and weight-bearing distal tibia. RESULTS: Participants with AN had lower WBLH and hip aBMD z scores than OAs and controls (P < 0.0001). Participants with AN and OAs had lower spine aBMD z scores than controls (P < 0.01). At the radius, total and cortical vBMD, percentage cortical area, and thickness were lower in the AN and OA groups than in controls (P ≤ 0.04); trabecular vBMD was lower in participants with AN than controls. At the tibia, participants with AN had lower measures for most parameters compared with OAs and controls (P < 0.05); OAs had lower cortical vBMD than controls (P = 0.002). Participants with AN and OAs had higher fracture rates than controls. Stress fracture prevalence was highest in OAs (P < 0.0001); nonstress fracture prevalence was highest in participants with AN (P < 0.05). CONCLUSION: AN is deleterious to bone at all sites and both bone compartments. A high stress fracture rate in OAs, who have comparable WBLH and hip aBMD measures to controls, indicates that BMD in these women may need to be even higher to avoid fractures.

Background: Child and adolescent sports participation continues to rise, often with specialization in a single sport at an early age. Psychological associations with sport specialization have been reported, although targeted research is lacking. Hypothesis/Purpose: The purpose of this study was to examine associations between sport specialization, levels of athletic identity, and coping skills among adolescent athletes. Methods: A cross-sectional survey study of sports medicine patients, 12-18 years, was performed. Athletes completed a one-time, voluntary, anonymous survey. Surveys included demographics, sport participation information, Athletic Identity Measurement Scale (AIMS,10-item, range 7-70), Jayanthi Sport Specialization Scale (range 0-6), and Athletic Coping Skills Inventory (ACSI, 7 subscales, range 0-84). Statistical analysis included Fisher’s exact tests, t-tests, Pearson correlations, and linear regression. Results: 334 out of 430 eligible patients completed surveys, with a response rate of 78%. Mean age was 15.0±1.8 years and participants were 64.6% female. 97.7% of participants designated participation in a primary sport, where they spent most of their time. Athletes reported starting this primary sport at a mean age of 7.2±3.7 years. Using the Jayanthi scale, 52.1% of respondents were classified as low specialization (score 0-3) and 47.9% as highly specialized (score 4-6). Sport specialization patterns did not significantly differ by age, sex, or sport. AIMS and Jayanthi scores positively correlated (r=0.39, pConclusion: Athletic identity was higher in athletes who were more specialized and started their primary sport earlier in life. Greater sport specialization may confer some advantages in developing coping strategies in young athletes, however these athletes may be at risk for more worry compared to less specialized athletes. [Table: see text]

Background:While sports participation is often associated with health benefits, a subset of athletes may develop impaired bone health. Bone stress injuries (BSIs) are a common overuse injury in athletes; site of injury has been shown to relate to underlying bone health in female athletes.Hypothesis/Purpose:This case series characterizes the association of type of sports participation and anatomic site of BSIs with low bone mineral density (BMD), defined as BMD Z-score Study Design:Cohort study; Level of evidence, 3.Methods:Chart review identified 28 male athletes aged 14 to 36 years with history of ≥1 lower-extremity BSI who were referred for evaluation of overall bone health, including assessment of lumbar spine, hip, and/or total body less head BMD per dual-energy x-ray absorptiometry. BMD Z-scores were determined via age, sex, and ethnicity normative values. Prior BSIs were classified by anatomic site of injury into trabecular-rich locations (pelvis, femoral neck, and calcaneus) and cortical-rich locations (tibia, fibula, femur, metatarsal and tarsal navicular). Sport type and laboratory values were also assessed in relationship to BMD. The association of low BMD to anatomic site of BSI and sport were evaluated with P value Results:Of 28 athletes, 12 (43%) met criteria for low BMD. Athletes with a history of trabecular-rich BSIs had a 4.6-fold increased risk for low BMD as compared with those with only cortical-rich BSIs (9 of 11 vs 3 of 17, P = .002). Within sport type, runners had a 6.1-fold increased risk for low BMD versus nonrunners (11 of 18 vs 1 of 10, P = .016). Laboratory values, including 25-hydroxy vitamin D, were not associated with BMD or BSI location.Conclusion:Low BMD was identified in 43% of male athletes in this series. Athletes participating in sports of running and with a history of trabecular-rich BSI were at increased risk for low BMD.

Lower rates of fracture in both Blacks compared to Whites, and men compared to women are not completely explained by differences in bone mineral density (BMD). Prior evidence suggests that more favorable cortical bone microarchitecture may contribute to reduced fracture rates in older Black compared to White women, however it is not known whether these differences are established in young adulthood or develop during aging. Moreover, prior studies using high-resolution pQCT (HR-pQCT) have reported outcomes from a fixed-scan location, which may confound sex- and race/ethnicity-related differences in bone structure.We determined differences in bone mass, microarchitecture and strength between young adult Black and White men and women.We enrolled 185 young adult (24.2±3.4yrs) women (n=51 Black, n=50 White) and men (n=34 Black, n=50 White) in this cross-sectional study. We used dual-energy X-ray absorptiometry (DXA) to determine areal BMD (aBMD) at the femoral neck (FN), total hip (TH) and lumbar spine (LS), as well as HR-pQCT to assess bone microarchitecture and failure load by micro-finite element analysis (μFEA) at the distal tibia (4% of tibial length). We used two-way ANOVA to compare bone outcomes, adjusted for age, height, weight and physical activity.The effect of race/ethnicity on bone outcomes did not differ by sex, and the effect of sex on bone outcomes did not differ by race/ethnicty. After adjusting for covariates, Blacks had significantly greater FN, TH and LS aBMD compared to Whites (p0.05 for all). Blacks also had greater cortical area, vBMD, and thickness, and lower cortical porosity, with greater trabecular thickness and total vBMD compared to Whites. μFEA-estimated FL was significantly higher among Blacks compared to Whites. Men had significantly greater total vBMD, trabecular thickness and cortical area and thickness, but greater cortical porosity than women, the net effects being a higher failure load in men than women.These findings demonstrate that more favorable bone microarchitecture in Blacks compared to Whites and in men compared to women is established by young adulthood. Advantageous bone strength among Blacks and men likely contributes to their lower risk of fractures throughout life compared to their White and women counterparts.

Context: Stress fractures are injuries caused by cumulative, repetitive stress that leads to abnormal bone remodeling. Specific populations, including female athletes and endurance athletes, are at higher risk than the general athletic population. Whereas more than 460 000 individuals participate in collegiate athletics in the United States, no large study has been conducted to determine the incidence of stress fractures in collegiate athletes. Objective: To assess the incidence of stress fractures in National Collegiate Athletic Association (NCAA) athletes and investigate rates and patterns overall and by sport. Design: Descriptive epidemiology study. Setting: National Collegiate Athletic Association institutions. Patients or Other Participants: National Collegiate Athletic Association athletes. Main Outcome Measure(s): Data were analyzed from the NCAA Injury Surveillance Program for the academic years 2004–2005 through 2013–2014. We calculated rates and rate ratios (RRs) with 95% confidence intervals (CIs). Results: A total of 671 stress fractures were reported over 11 778 145 athlete-exposures (AEs) for an overall injury rate of 5.70 per 100 000 AEs. The sports with the highest rates of stress fractures were women's cross-country (28.59/100 000 AEs), women's gymnastics (25.58/100 000 AEs), and women's outdoor track (22.26/100 000 AEs). Among sex-comparable sports (baseball/softball, basketball, cross-country, ice hockey, lacrosse, soccer, swimming and diving, tennis, indoor track, and outdoor track), stress fracture rates were higher in women (9.13/100 000 AEs) than in men (4.44/100 000 AEs; RR = 2.06; 95% CI = 1.71, 2.47). Overall, stress fracture rates for these NCAA athletes were higher in the preseason (7.30/100 000 AEs) than in the regular season (5.12/100 000 AEs; RR = 1.43; 95% CI = 1.22, 1.67). The metatarsals (n = 254, 37.9%), tibia (n = 147, 21.9%), and lower back/lumbar spine/pelvis (n = 81, 12.1%) were the most common locations of injury. Overall, 21.5% (n = 144) of stress fractures were recurrent injuries, and 20.7% (n = 139) were season-ending injuries. Conclusions: Women experienced stress fractures at higher rates than men, more often in the preseason, and predominantly in the foot and lower leg. Researchers should continue to investigate biological and biomechanical risk factors for these injuries as well as prevention interventions.

OBJECTIVE Both estrogen and exercise may have cognition enhancing benefits; however, young oligomenorrheic/amenorrheic athletes (OA) with estrogen deficiency have not been evaluated for cognitive deficits. Our objective was to determine whether 6 months of estrogen replacement will impact cognitive domains in OA. We hypothesized that estrogen replacement would improve verbal memory and executive control in OA. METHODS We performed cognitive assessments at baseline and after 6 months in 48 OA (14-25 years) randomized to estrogen (EST+) (oral 30 µg ethinyl estradiol [n = 16] or transdermal 100 µg 17-β-estradiol patch [n = 13]) or no estrogen (EST-) (n = 19) in an ongoing clinical trial. Neurocognitive testing included California Verbal Learning Test-Second Edition (CVLT-II) (for verbal memory) and Delis-Kaplan Executive Function System Color-Word Interference Test (D-KEFS-CWIT) (executive control). RESULTS On average, subjects (mean ± SEM age: 19.9 ± 3.1 years, body mass index: 20.6 ± 2.3 kg/m²) participated in 10.3 ± 5.9 hours per week of weight-bearing activities of their lower limbs. The EST+ group performed better for CVLT-II verbal memory scores for immediate recall over 6 months of therapy compared to EST- (P < .05) even after controlling for baseline scores and age. Changes in D-KEFS-CWIT scores over 6 months did not differ between the groups. However, the EST+ group had greater improvements in inhibition-switching completion time over 6 months compared with the EST- group after controlling for baseline scores and age (P = .01). CONCLUSIONS OA show improvements in verbal memory and executive control following 6 months of estrogen replacement. These findings in athletes, who are in their prime of neurocognitive development, underscore the need for future studies exploring cognition in OA. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT00946192.

Cosponsoring associations The American Society for Reproductive Medicine, the European Society of Endocrinology, and the Pediatric Endocrine Society. This guideline was funded by the Endocrine Society. Objective To formulate clinical practice guidelines for the diagnosis and treatment of functional hypothalamic amenorrhea (FHA). Participants The participants include an Endocrine Society-appointed task force of eight experts, a methodologist, and a medical writer. Evidence This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation approach to describe the strength of recommendations and the quality of evidence. The task force commissioned two systematic reviews and used the best available evidence from other published systematic reviews and individual studies. Consensus process One group meeting, several conference calls, and e-mail communications enabled consensus. Endocrine Society committees and members and cosponsoring organizations reviewed and commented on preliminary drafts of this guideline. Conclusions FHA is a form of chronic anovulation, not due to identifiable organic causes, but often associated with stress, weight loss, excessive exercise, or a combination thereof. Investigations should include assessment of systemic and endocrinologic etiologies, as FHA is a diagnosis of exclusion. A multidisciplinary treatment approach is necessary, including medical, dietary, and mental health support. Medical complications include, among others, bone loss and infertility, and appropriate therapies are under debate and investigation.

Background Femoral neck stress fractures are rare in healthy children, with only 9 cases previously reported. The present article reviews our institutional experience with femoral neck stress fractures in children younger than 10 years of age, to highlight the unique features of this condition. Methods We undertook a retrospective review of clinical records of patients who had been treated at our institution for an idiopathic femoral neck stress fracture between 2000 and 2014. To focus on children rather than adolescents, the World Health Organization's definition of adolescent as a person between 10 and 19 years of age was used; we thereby limited our analysis to patients younger than 10 years of age. Results The study included 6 patients (3 males, 3 females) treated for an idiopathic femoral neck stress fracture, with a mean age at diagnosis of 7.7 years (range, 5.2 to 8.9 y). All patients presented with a limp, which worsened with activity and had persisted for a mean of 5 weeks (range, 2 to 9 wk). None of the patients had experienced an increase in activity level or sporting volume before symptom onset. On examination, 3 patients experienced pain with terminal hip flexion and 3 patients demonstrated pain-free hip range of motion. Plain radiography demonstrated inferior femoral neck cortical disruption, suggesting a compression-type stress fracture mechanism. The diagnosis was confirmed by cross-sectional imaging in all cases. All patients were initially treated with 6 to 8 weeks of non-weight-bearing followed by 4 to 6 weeks of partial weight-bearing, leading to complete healing in 4 patients. Two patients demonstrated incomplete healing and were managed with spica casting for an additional 6 weeks. Conclusions Our case series illustrates the unique features of this rare condition in children, with a history and examination profile distinct from those of adolescents and adults. Compliance with weight-bearing restrictions is difficult in this population and hip spica casting may be required to permit complete healing. Level of evidence Level IV-case series.

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.

Transdermal, but not oral, estrogen replacement improves bone mineral density (BMD) in athletes with oligo-amenorrhea (OA). Our objective was to determine mechanisms that may explain the impact of route of estrogen administration on bone outcomes. Whereas IGF-1 is bone anabolic, sclerostin, preadipocyte factor-1 (Pref-1) and brain derived neurotropic factor (BDNF) inhibit bone formation, and an effect of estrogen on these factors has been demonstrated in other populations. However, few studies have examined the impact of route of estrogen administration on these factors in adolescents and young adults. Further, it is unclear how the route of estrogen administration impacts bioavailable testosterone, which in turn may impact bone outcomes in young oligo-amenorrheic women. 73 OA 14-25 years old received (i) a 17β-estradiol transdermal patch continuously with cyclic oral micronized progesterone (PATCH), (ii) a combined ethinyl estradiol and desogestrel pill (PILL), or (iii) no estrogen/progesterone (NONE) for 12-months. We evaluated fasting morning levels of a marker of bone formation [N-terminal propeptide of type 1 procollagen (P1NP)], a marker of bone resorption [N-telopeptide (NTX)], IGF-1, insulin-like growth factor binding protein 3 (IGFBP3), total testosterone, estradiol, sex hormone-binding globulin (SHBG), sclerostin, Pref-1, BDNF, calcium, 25(OH) vitamin D, and parathyroid hormone (PTH) at baseline and 12-months. Groups did not differ for age, weight, exercise activity or markers of bone formation at baseline. We have previously reported increases in areal BMD Z-scores at the spine and femoral neck in the PATCH compared to PILL and NONE groups (Ackerman et al: BJSM Oct. 2018). Over 12 months, between group analysis showed greatest decreases of P1NP in the PILL group (p=0.03) associated with a decrease in IGF-1 and IGF1/IGFBP-3 ratio (r=0.33, p≤0.05), and an increase in SHBG (r=-0.28;p=0.02). Within group analysis showed that sclerostin, Pref-1 and BDNF decreased in the PATCH group over 12 months (p=0.01, 0.01 and 0.04 respectively). PATCH group had the greatest increases in estradiol (p=0.0009), and estradiol increases were associated with increases in BMD. Groups did not differ for changes in NTX. Transdermal 17β-estradiol does not cause the decrease in IGF-1 and SHBG observed with oral ethinyl estradiol. It leads to decreases in sclerostin, Pref-1 and BDNF. These effects may mediate the beneficial effects of transdermal estrogen on bone in young women.

The Wnt-β-catenin pathway receptor, low-density lipoprotein receptor-related protein 5 (LRP5), is a known regulator of bone mineral density. It has been hypothesized that specific human polymorphisms in LRP5 impact bone density, in part, by altering the anabolic response of bone to mechanical loading. Although experiments in animal models support this hypothesis, there is limited evidence that LRP5 polymorphisms can alter the anabolic response of bone to mechanical loading in humans. Herein, we report a young male who harbors a rare LRP5 missense mutation (A745V) and who provides potential proof of principle for this mechanotransduction hypothesis for low bone density. The subject had no history of fractures until age 18, a year into a career in competitive distance running. As he continued to run over the following 2 years, his mileage threshold to fracture steadily and rapidly decreased until he was diagnosed with severe osteoporosis (lumbar spine BMD Z-score of -3.2). By contextualizing this case within the existing LRP5 and mechanical stress literature, we speculate that this represents the first documented case of an individual in whom a genetic mutation altered the anabolic response of bone to mechanical stress in a manner sufficient to contribute to osteoporosis.

This study’s objective was to identify differences in risk for low energy availability and athletic clearance level by comparing scores on Female Athlete Triad Cumulative Risk Assessment (Triad CRA) and Relative Energy Deficiency in Sport Clinical Assessment Tool (RED-S CAT). A total of 1,000 female athletes aged 15–30 years participating in ≥4 hr of physical activity/week for the previous ≥6 months completed an extensive survey assessing health, athletic history, family disease history, and specific Triad/RED-S risk factors. Retrospective chart review ascertained laboratory and bone mineral density measures. Triad CRA and RED-S CAT were used to assign each athlete’s risk level (low, moderate, and high), and case-by-case comparison measured the level of agreement between the tools. We hypothesized that the tools would generally agree on low-risk athletes and that the tools would be less aligned in the specific elevated risk level (moderate or high). Most of the sample was assigned moderate or high risk for Triad CRA and RED-S CAT (Triad: 54.7% moderate and 7.9% high; RED-S: 63.2% moderate and 33.0% high). The tools agreed on risk for 55.5% of athletes. Agreement increased to 64.3% when only athletes with bone mineral density measurements were considered. In conclusion, Triad CRA and RED-S CAT provide consensus on the majority of athletes at elevated (moderate or high) risk for low energy availability, but have less agreement on the specific risk level assigned.

Previous studies have demonstrated that an individual’s race and ethnicity are important determinants of their areal bone mineral density (aBMD), assessed by dual-energy X-ray absorptiometry. However, there are few data assessing the impact of race on bone microarchitecture and strength estimates, particularly in older adolescent girls and young adults. We hypothesized that bone microarchitecture and strength estimates would be superior in Blacks compared to White and Asian American adolescent girls and young adults of similar age based on reports of higher aBMD in Blacks. We assessed BMD using dual-energy X-ray absoptiometry (DXA), bone microarchitecture at the distal radius and distal tibia using high-resolution peripheral quantitative computed tomography (HRpQCT) and estimated measures of bone strength using micro-finite element analysis (FEA) in 35 White, 15 Asian American, and 10 Black girls 14–21 years. After controlling for height, most DXA measures of aBMD and aBMD Z scores were higher in Black girls compared with Whites and Asian Americans. HRpQCT and FEA showed that at the distal radius, Blacks had greater cortical perimeter, cortical area, trabecular thickness, trabecular BMD, estimated failure load, and stiffness than the other two groups. For the distal tibia, trabecular number and BMD were higher in Blacks than Asian Americans. Particularly at the distal radius, adolescent and young adult White and Asian American girls have less favorable bone microarchitecture and lower bone strength than Blacks, possibly explaining the lower risk of fracture seen in Blacks. Level II