Low energy availability surrogates are associated with Relative Energy Deficiency in Sport outcomes in male athletes.

OBJECTIVES: To determine the association between surrogates of low energy availability (EA) and proposed health and performance outcomes of Relative Energy Deficiency in Sport (REDs) in a clinical sample of adolescent and young adult male athletes. METHODS: Male athletes ages 15-30 years presenting to a sports medicine clinic at two tertiary care centres were invited to complete a survey about athlete health and well-being. Participants were divided into low EA and adequate EA groups based on survey responses. The associations between low EA and REDs outcomes were evaluated using χ2 tests and ORs were calculated using binomial logistic regression (significance: p<0.05). RESULTS: Low EA was associated with increased frequency of self-reported immunological, metabolic, psychological, cardiovascular and gastrointestinal dysfunction; reduced endurance performance, response to training, judgement, coordination and muscle strength; and increased irritability and depression. Low EA athletes were more likely to have self-reported cardiovascular dysfunction (OR 2.87, 95% CI 1.56 to 5.26) and psychological illness (OR 3.23, 95% CI 1.91 to 5.41), decreased training response (OR 2.64, 95% CI 1.38 to 5.03) and endurance performance (OR 2.26, 95% CI 1.13 to 4.52) and were less likely to have self-reported gonadal dysfunction (OR 0.49, 95% CI 0.30 to 0.81), than adequate EA athletes (p<0.05). CONCLUSIONS: Low EA surrogates are associated with many adverse health outcomes and performance effects of REDs in male athletes. More prospective REDs research in males is needed to improve various aspects of REDs screening in young male athletes.

Multi-organ transcriptome atlas of a mouse model of relative energy deficiency in sport.

Insufficient energy intake to meet energy expenditure demands of physical activity can result in systemic neuroendocrine and metabolic abnormalities in activity-dependent anorexia and relative energy deficiency in sport (REDs). REDs affects >40% of athletes, yet the lack of underlying molecular changes has been a hurdle to have a better understanding of REDs and its treatment. To assess the molecular changes in response to energy deficiency, we implemented the "exercise-for-food" paradigm, in which food reward size is determined by wheel-running activity. By using this paradigm, we replicated several aspects of REDs in female and male mice with high physical activity and gradually reduced food intake, which results in weight loss, compromised bone health, organ-specific mass changes, and altered rest-activity patterns. By integrating transcriptomics of 19 different organs, we provide a comprehensive dataset that will guide future understanding of REDs and may provide important implications for metabolic health and (athletic) performance.

Nutritional Assessment, Body Composition, and Low Energy Availability in Sport Climbing Athletes of Different Genders and Categories: A Cross-Sectional Study.

Climbing is an Olympic discipline in full development and multidisciplinary in nature, where the influences of body composition and nutritional status on performance have not yet been clarified despite the quest for a low weight in anti-gravity disciplines such as climbing. The present cross-sectional study aimed to conduct nutritional (3-day dietary diaries) and body composition (ISAK profile) assessments on sport climbing athletes by gender and climbing level during the months of February and March 2024. The t-test for independent samples and the Mann-Whitney U-test, as well as an ANOVA and the Kruskal-Wallis H-test, were used to compare the distributions of two or more groups, respectively, and Pearson's and Spearman's correlation coefficients were used to estimate the correlations between the different variables. The mean age of the 46 Spanish climbers (22 men and 24 women) was 30 years (SD: 9) with 7.66 years of experience (SD: 6.63). The mean somatotype of the athletes was classified as balanced mesomorph. Negative correlations were observed between fat mass variables and climbing level (p < 0.010), and positive correlations were observed with forearm circumference (p < 0.050). The mean energy availability (EA) was 33.01 kcal-kg FFM-1d-1 (SD: 9.02), with 55.6% of athletes having a suboptimal EA status and 35.6% having low energy availability (LEA). The carbohydrate and protein intakes were below the recommendations in 57.8% and 31.1% of athletes, respectively. There were deficient intakes of all micronutrients except phosphorus in males. These findings suggest that climbing athletes are at a high risk of developing low energy availability states and concomitant problems. Optimal nutritional monitoring may be advisable in this type of athlete to try to reduce the risk of LEA.

Application of the IOC Relative Energy Deficiency in Sport (REDs) Clinical Assessment Tool version 2 (CAT2) across 200+ elite athletes.

OBJECTIVE: This cross-sectional retrospective and prospective study implemented the 2023 International Olympic Committee Relative Energy Deficiency in Sport (REDs) Clinical Assessment Tool version 2 (CAT2) to determine the current severity of REDs (primary outcome) and future risk of bone stress injuries (BSI, exploratory outcome) in elite athletes. METHODS: Female (n=143; 23.3±4.3 years) and male (n=70; 23.1±3.7 years) athletes (performance tier 3 (52%), tier 4 (36%), tier 5 (12%)) participated in a baseline CAT2 (with minor modifications) assessment, including a self-report questionnaire (menstrual function (females), BSI, Eating Disorder Examination Questionnaire (EDE-Q)), bone mineral density (BMD via DXA) and fasted blood analysis (triiodothyronine (T3), testosterone, cholesterol). Athletes were assigned a green, yellow, orange or red light via CAT2. The prospective risk of new self-report of physician-diagnosed BSI was assessed over a subsequent 6-24 months. RESULTS: REDs prevalence was 55% green, 36% yellow, 5% orange and 4% red light. The CAT2 identified a greater prevalence of amenorrhoea and BSI and lower T3, testosterone and BMD (p<0.01) in red, orange and yellow (those with REDs) versus green light. ORs for a prospective self-reported BSI (majority physician diagnosed) were greater in orange vs green (OR 7.71, 95% CI (1.26 to 39.83)), in females with severe amenorrhoea (OR 4.6 (95% CI 0.98 to 17.85)), in males with low sex drive (OR 16.0 (95% CI 4.79 to 1038.87)), and athletes with elevated EDE-Q global scores (OR 1.45 (95% CI 0.97 to 1.97)). CONCLUSION: The CAT2 has high validity in demonstrating current severity of REDs, with increased future risk of self-reported BSI in athletes with a more severe REDs traffic light category.

A literature review of biomarkers used for diagnosis of relative energy deficiency in sport.

Introduction: The review aims to summarize the markers used in diagnosing relative energy deficiency in sport (REDs) and compare them with the REDs CAT2 score. Methods: A systematic search was performed in the PubMed, Web of Science, and SPORTDiscus databases during April 2023. The descriptors used were "athlete" AND "REDs," along with respective entry terms. The selection process followed the PRISMA 2020 recommendations, identifying 593 records, from which 13 studies were ultimately selected. Seventy-nine markers were identified and categorized into six groups: bone mineral density (BMD), metabolic resting rate, blood biomarkers, anthropometrics, nutritional intake, and performance parameters. The most frequently utilized biomarkers included BMD, anthropometric parameters (e.g., body mass index, body mass, and fat mass), and the triiodothyronine (T3) concentration. Results: According to the REDs CAT2 pointed indicators, the biomarkers varied among the studies, while 7 out of the 13 included studies achieved a ≥60% agreement rate with this tool. The prevalence of low energy availability, an etiological factor in the development of REDs, was detected in 4 out of 13 studies, with an average of 39.5%. Conclusion: In conclusion, this review highlights the most commonly used markers in diagnosing REDs, such as BMD, anthropometric parameters, and T3 hormone concentration. Due to the current inconsistencies, standardizing diagnostic methodologies is crucial for future research. By focusing on widely used markers, this review aids future research planning and result interpretation and points out the ongoing need for methodological consistency in evolving diagnostic tools. Systematic Review Registration: https://www.crd.york.ac.uk/, PROSPERO (CRD42022320007).

Risk and prevalence of Relative Energy Deficiency in Sport (REDs) among professional female football players.

A high prevalence of low energy availability (LEA) has been reported in female football players. This is of concern as problematic LEA may evolve into a syndromic pattern known as relative energy deficiency in sport (REDs). Given the difficulties in accurately assessing LEA, our study shifts emphasis to measurable indicators of REDs, serving as proxies for health detriments caused by LEA. The present cross-sectional study aimed to quantify the risk of REDs and to assess the prevalence of indicators indicative of the syndrome. 60 players (tiers 3 and 4) from three Norwegian football teams were analyzed as a single cohort but also stratified based on player position and menstrual status. The proportion of players at risk for REDs was 22%, that is, 17% with mild, 3% with moderate to high, and 2% with very high/extreme risk, respectively. The majority of the cohort (71%) presented with no primary indicators, while 20%, 7%, and 2% presented with one, two, and three primary indicators, respectively. Regarding secondary indicators, 57% had none, 33% had one, and 10% had two indicators. For associated indicators, 30% had none, 42% had one, 18% had two, 8% had three, and 2% had four indicators. Player position did not affect the prevalence of REDs indicators. Among noncontraceptive users (n = 27), secondary amenorrhea (AME) was reported by 30%. These findings indicate that health and performance teams should prioritize universal health promoting strategies rather than selective or indicative strategies. Particularly, focus on nutritional periodization to secure sufficient energy availability, mitigating the risk of problematic LEA and REDs should be addressed.

The risk of low energy availability among athlete females in Saudi Arabia: a cross-sectional study.

Introduction: Low energy availability (LEA) is a state of inadequate energy reserves that results from a negative energy balance. This condition can lead to severe health risks such as amenorrhea and osteoporosis. Various causes for LEA, such as eating disorders and exercise addiction, have been reported in the literature. However, data in Saudi Arabia are lacking. This cross-sectional study measures the prevalence of LEA, eating disorders, and exercise addiction among adult females in Saudi Arabia and identifies possible associated risk factors. Methods: The sample comprised 119 female athletes who filled out an online survey adapted from the LEA in Females Questionnaire, the Eating Disorder Examination Questionnaire, and the Exercise Addiction Inventory. Results: Participants showed a high prevalence of LEA (66.4%), eating disorder (33.6%), and exercise addiction (10.1%), confirming the association between normal weight and LEA in females living in Saudi Arabia (p < 0.00). Discussion and conclusion: With an increasing number of females in the country interested in following a healthy lifestyle, there is a need to raise the awareness of the population on the issues of LEA, eating disorders, and exercise addiction and their effects on the body by developing educational programs about energy intake and healthy physical activity routines.

Energy availability modulates regional blood flow via estrogen-independent pathways in regularly menstruating young women.

PURPOSE: This study aimed to investigate the impact of short-term low energy availability (LEA) on vascular function in young, regularly menstruating women. METHODS: Participants were 19 women, aged 22.9 ± 4.2 years, with body mass index 18-30 kg·m2. They were divided into two groups and completed two conditions in a crossover design: a 3-day control condition (CON) with an energy availability of 45 kcals·kgFFM-1·day-1 and a 3-day LEA condition of 15 kcals·kgFFM-1 day-1. Assessments were conducted during the early follicular phase of the menstrual cycle. Outcome measures included forearm blood flow (FBF), heart rate, blood pressure, arterial stiffness, resting energy expenditure (REE), metabolic blood markers and body composition. RESULTS: Significant time-by-condition interactions were found for resting FBF (p = .004), REE (p = .042), triiodothyronine (p = .006), ß-hydroxybutyrate (p = .002) and body mass (p < .001). Resting FBF was 1.43 ± 1.01 and 1.31 ± 0.61 (arbitrary units) at pre and post, respectively, in LEA and 1.52 ± 0.7 and 1.76 ± 0.57 at pre and post in CON. The LEA condition led to a decrease in triiodothyronine (pre: 1.54 ± 0.28, post: 1.29 ± 0.27 ng ml-1), REE (pre: 1588 ± 165, post: 1487 ± 160 kcals day-1) and body mass (pre: 61.4 ± 7.5, post: 59.6 ± 7.3 kg). Changes in resting FBF were significantly correlated with changes in REE in the LEA condition (r = 0.53; p = 0.02). CONCLUSION: Short-term LEA modifies regional blood flow and this might contribute to the observed decreased in REE. Findings emphasize the need for careful management of energy availability in populations at risk of LEA.

The relationship between nutrition knowledge and low energy availability risk in collegiate athletes.

OBJECTIVES: This was a pilot study that examined the relationship between nutrition knowledge and risk for low energy availability (LEA) in NCAA athletes. METHODS: Athletes (64.4 % female, 35.6 % male) completed the Abridged Nutrition for Sport Knowledge Questionnaire (A-NSKQ) and either the Low Energy Availability in Females Questionnaire (LEAF-Q) or Male Athlete Triad (MAT) screening questions. RESULTS: Females at risk for LEA had higher nutrition knowledge, demonstrated by higher A-NSKQ scores, than those classified as low risk (16.5 vs 14.5, p = 0.01). There was a very weak correlation between MAT and A-NSKQ scores (R2 = 0.012).

Assessment of Relative Energy Deficiency in Sport (REDs) Risk among Adolescent Acrobatic Gymnasts.

Energy imbalance exposes athletes to relative energy deficiency in sports (REDs) syndrome. Data on energy consumption, REDs, and bone mineral density (BMD) in adolescent acrobatic gymnasts, especially in males, are scarce. Our aim was to examine the eating habits, energy balance, body composition, and BMD of these athletes. In this study, 18 healthy adolescents participating in competitive acrobatic gymnastics completed a questionnaire, underwent a dual-energy X-ray absorptiometry scan (DXA), received a food log, and had their activities monitored for 3 days. Eighteen acrobats were enrolled (mean age: 14.3 ± 1.2 years; males: 6/18). The mean total body BMD Z-score was 0.4 ± 1.0. Top-position acrobats (7/18) had significantly lower total body BMD Z-scores than base-positioned acrobats (-0.2 ± 0.3 vs. 0.8 ± 0.3, p = 0.032), though their forearms were not significantly different (0.2 ± 0.5 vs. 0.8 ± 0.7, p = 0.331). No sex differences were found for BMD Z-scores, BMI, or energy availability. The BMD parameters of the acrobats were within the normal range for a healthy pediatric population, although three had low BMDs (<-1 SD) for healthy athletes. Total body and LS BMD Z-scores were significantly lower in top-position athletes compared to base-position athletes. These findings suggest personalized (top vs. base) training programs (high-impact training) that may achieve better health outcomes.

Relative Energy Deficiency in Sport (REDs): Endocrine Manifestations, Pathophysiology and Treatments.

Research on lean, energy-deficient athletic and military cohorts has broadened the concept of the Female Athlete Triad into the Relative Energy Deficiency in Sport (REDs) syndrome. REDs represents a spectrum of abnormalities induced by low energy availability (LEA), which serves as the underlying cause of all symptoms described within the REDs concept, affecting exercising populations of either biological sex. Both short- and long-term LEA, in conjunction with other moderating factors, may produce a multitude of maladaptive changes that impair various physiological systems and adversely affect health, well-being, and sport performance. Consequently, the comprehensive definition of REDs encompasses a broad spectrum of physiological sequelae and adverse clinical outcomes related to LEA, such as neuroendocrine, bone, immune, and hematological effects, ultimately resulting in compromised health and performance. In this review, we discuss the pathophysiology of REDs and associated disorders. We briefly examine current treatment recommendations for REDs, primarily focusing on nonpharmacological, behavioral, and lifestyle modifications that target its underlying cause-energy deficit. We also discuss treatment approaches aimed at managing symptoms, such as menstrual dysfunction and bone stress injuries, and explore potential novel treatments that target the underlying physiology, emphasizing the roles of leptin and the activin-follistatin-inhibin axis, the roles of which remain to be fully elucidated, in the pathophysiology and management of REDs. In the near future, novel therapies leveraging our emerging understanding of molecules and physiological axes underlying energy availability or lack thereof may restore LEA-related abnormalities, thus preventing and/or treating REDs-related health complications, such as stress fractures, and improving performance.

Association between Low Energy Availability (LEA) and Impaired Sleep Quality in Young Rugby Players.

Low energy availability (LEA) has been associated with several physiological consequences, but its impact on sleep has not been sufficiently investigated, especially in the context of young athletes. This study examined the potential association between energy availability (EA) status and objective sleep quality in 42 male rugby players (mean age: 16.2 ± 0.8 years) during a 7-day follow-up with fixed sleep schedules in the midst of an intensive training phase. Participants' energy intake was weighed and recorded. Exercise expenditure was estimated using accelerometry. Portable polysomnography devices captured sleep on the last night of the follow-up. Mean EA was 29.3 ± 9.14 kcal·kg FFM-1·day-1, with 47.6% of athletes presenting LEA, 35.7% Reduced Energy Availability (REA), and 16.7% Optimal Energy Availability (OEA). Lower sleep efficiency (SE) and N3 stage proportion, along with higher wake after sleep onset (WASO), were found in participants with LEA compared to those with OEA (p = 0.04, p = 0.03 and p = 0.005, respectively, with large effect sizes). Segmented regression models of the EA-sleep outcomes (SE, sleep onset latency [SOL]), WASO and N3) relationships displayed two separate linear regions and produced a best fit with a breakpoint between 21-33 kcal·kg FFM-1·day-1. Below these thresholds, sleep quality declines considerably. It is imperative for athletic administrators, nutritionists, and coaches to conscientiously consider the potential impact of LEA on young athletes' sleep, especially during periods of heavy training.

Risk Factors for Running-Related Injury in High School and Collegiate Cross-country Runners: A Systematic Review.

OBJECTIVE: To summarize and describe risk factors for running-related injuries (RRIs) among high school and collegiate cross-country runners. DESIGN: Descriptive systematic review. LITERATURE SEARCH: Four databases (Scopus, SPORTDiscus, CINAHL, Cochrane) were searched from inception to August 2023. STUDY SELECTION CRITERIA: Studies assessing RRI risk factors in high school or collegiate runners using a prospective design with at least 1 season of follow-up were included. DATA SYNTHESIS: Results across each study for a given risk factor were summarized and described. The NOS and GRADE frameworks were used to evaluate quality of each study and certainty of evidence for each risk factor. RESULTS: Twenty-four studies were included. Overall, study quality and certainty of evidence were low to moderate. Females or runners with prior RRI or increased RED-S (relative energy deficiency in sport) risk factors were most at risk for RRI, as were runners with a quadriceps angle of >20° and lower step rates. Runners with weaker thigh muscle groups had increased risk of anterior knee pain. Certainty of evidence regarding training, sleep, and specialization was low, but suggests that changes in training volume, poorer sleep, and increased specialization may increase RRI risk. CONCLUSION: The strongest predictors of RRI in high school and collegiate cross-country runners were sex and RRI history, which are nonmodifiable. There was moderate certainty that increased RED-S risk factors increased RRI risk, particularly bone stress injuries. There was limited evidence that changes in training and sleep quality influenced RRI risk, but these are modifiable factors that should be studied further in this population. J Orthop Sports Phys Ther 2024;54(2):1-13. Epub 16 November 2023. doi:10.2519/jospt.2023.11550.

Hormonal contraception for female athletes presents special needs and concerns.

PURPOSE: Oral contraceptives (OCs) are commonly used by female athletes raising concerns regarding the possible adverse effects of OCs on physical performance, musculoskeletal injuries, and bone density. We aimed to review all current studies on the physiological effects of OCs in physically active women. MATERIALS AND METHODS: A review of literature in electronic search in PubMed and Google Scholar databases from December 2002 to December 2022 using relevant keywords. The reference lists of the articles found eligible were also reviewed. RESULTS: Out of 344 articles in the initial database, 54 clinical studies were eligible for inclusion in our literature review. OCs are used by about two-thirds of female athletes. Current research suggests that OCs' effects on endurance performance and muscle strength are mostly reassuring. OCs do not seem to have a major negative impact on bone health or sports injuries. In fact, new data suggests that they may even significantly reduce the risk of anterior cruciate ligament (ACL) injury. CONCLUSIONS: OCs can be safely used by young female athletes, who may also benefit from better menstrual cycle control. OCs offer newly realised protection from ACL injuries. The use of OCs must be carefully individualised according to their preferences, expectations, and experience.

Hormonal contraception can be safely prescribed to active women. The International Olympic Committee advocates a new and wider definition for the 'athlete triad', where low energy availability presents a special challenge for these athletes. New data suggests that the use of oral contraceptives may protect against ACL injury.

Differences in Knowledge of Female Athlete Triad and Relative Energy Deficiency in Sport in Female Cross-Country Athletes.

BACKGROUND: Female Athlete Triad (Triad) and Relative Energy Deficiency in Sport (REDs) describe potential health and performance consequences of low energy availability. OBJECTIVE: We surveyed female cross-country athletes to assess differences in educational impact scores (knowledge score * confidence score factor, EIS) of Triad and REDs. Associations between EIS and participant characteristics [e.g., mileage (current and peak), years of running experience, age, bone stress injury history, division level participation, academic area of study, Triad or REDs diagnoses, and Triad or REDs education] were explored. MATERIALS & METHODS: An evidence-based online survey was developed and administered via Qualtrics™ to female collegiate cross-country athletes (n = 275; age = 20 ± 1 yrs). RESULTS: There was a weak correlation between peak career mileage and EIS (r = 0.195; p = 0.010). EIS significantly differed in athletes with a related academic area of study vs. those without (21.91 ± 5.16, 16.11 ± 5.54, respectively). EIS significantly differed in athletes with Triad and REDs diagnoses (21.69 ± 5.85 and 22.58 ± 6.82, respectively) vs. those without (16.80 ± 6.54 and 17.20 ± 6.34, respectively). EIS was higher in those who had received Triad education vs. those who had not (21.03 ± 6.86, 18.12 ± 6.82, respectively). A significant interaction between peak career mileage and Triad diagnosis was found (p = 0.005). CONCLUSIONS: Significant education-based and diagnoses differences suggests that Triad diagnoses correlate with peak career mileage. These findings support education to improve not only treatment, but prevention, of Triad and REDs.

Clinical assessment, treatment, and referral trends for adolescent runners seeking care at an injured runners' clinic.

PURPOSE: Over a 10-year time frame, this study aimed to evaluate diagnosis, treatment, and referral trends for adolescent runners seeking care for running-related injuries (RRIs) at a clinic that specializes in running medicine. METHODS: This study was a retrospective chart review of 392 adolescent runners (2,326 encounters) who sought care for RRIs between the years 2011 and 2021. Descriptive statistics were used to summarize clinical assessments, referrals, assistive devices, and medications prescribed or administered overall and by injury type. Chi-square analyses were used to compare proportions of services rendered across the 10-year time frame. RESULTS: Patients most frequently received manual evaluations or special tests during clinic visits. Most visits resulted in at least one referral (91%), primarily for physical therapy or gait-training. Assistive devices and medications/supplements were offered at only 18% of patient visits. The majority of assessments (X2 = 69.7, p = 0.002), treatments (X2: 23.6-43.8, p: <  0.001-0.003), and referrals (X2 = 132, p <  0.001) were for shin injuries. Larger proportions of nutrition assessments (X2 = 40.7, p <  0.001), interventions (X2 = 26.8, p = 0.003), and referrals (X2 = 27.5, p = 0.002) were performed in or after the year 2015. CONCLUSION: Clinic visits for shin injuries required the most clinical resources per episode of care. There were observed shifts in clinical assessment and treatment approaches to include more expanded nutritional and physiologic considerations.

Prevalence of low energy availability in 25 New Zealand elite female rowers - A cross sectional study.

OBJECTIVES: To quantify energy availability (EA) in elite female rowers, determine its association with bone mineral density (BMD), and examine the ability of the low energy availability in females-questionnaire (LEAF-Q) and brief eating disorder in athletes-questionnaire (BEDA-Q) to distinguish between low and normal EA. DESIGN: Observational cross-sectional study. METHODS: Twenty-five elite female rowers participated in the study. EA was calculated by means of a 4-day food intake diary and analysis of training load. Low energy availability (LEA) was defined as EA <30 kCal * kg-1 * FFM-1 * day-1. Dual-energy X-ray absorptiometry (DXA) was used to assess fat free mass (FFM) and BMD Z-scores. LEA risk was assessed using the LEAF-Q and BEDA-Q. RESULTS: The mean EA was 23.2 ±â€¯12.2 kCal * kg-1 * FFM-1 * day-1. Prevalence of LEA was 64 %. The mean BMD Z-score was 1.6 ±â€¯0.6 (range: 0.7 to 2.9). Athletes with LEA had a significantly higher BEDA-Q score than the group with normal EA (mean 0.30 ±â€¯0.17 vs. 0.09 ±â€¯0.11, P < 0.05), but LEAF-Q score was not different between groups (mean 10.4 ±â€¯4.6, 8.2 ±â€¯4.5, P = 0.29). CONCLUSION: Low energy availability is common amongst elite female rowers in New Zealand and is positively correlated with higher scores on the BEDA-Q. Bone mineral density was normal irrespective of EA status.

Considerations of Low Carbohydrate Availability (LCA) to Relative Energy Deficiency in Sport (RED-S) in Female Endurance Athletes: A Narrative Review.

The purpose of this narrative review is to identify health and performance consequences associated with LCA in female endurance athletes. The intake of carbohydrates (CHO) before, during, and after exercise has been demonstrated to support sport performance, especially endurance activities which rely extensively on CHO as a fuel source. However, low energy availability (LEA) and low carbohydrate availability (LCA) are common in female athletes. LEA occurs when energy intake is insufficient compared to exercise energy expenditure, and LEA-related conditions (e.g., Female Athlete Triad (Triad) and Relative Energy Deficiency in Sport (RED-S)) are associated with a myriad of health and performance consequences. The RED-S model highlights 10 health consequences and 10 performance consequences related to LEA. The independent effect of LCA on health and performance has been under-researched, despite current CHO intake being commonly insufficient in athletes. It is proposed that LCA may not only contribute to LEA but also have independent health and performance consequences in athletes. Furthermore, this review highlights current recommendations for CHO intake, as well as recent data on LCA prevalence and menstrual cycle considerations. A literature review was conducted on PubMed, Science Direct, and ResearchGate using relevant search terms (i.e., "low carbohydrate/energy availability", "female distance runners"). Twenty-one articles were identified and twelve met the inclusion criteria. The total number of articles included in this review is 12, with 7 studies illustrating that LCA was associated with direct negative health and/or performance implications for endurance-based athletes. Several studies included assessed male athletes only, and no studies included a female-only study design. Overall, the cumulative data show that female athletes remain underrepresented in sports science research and that current CHO intake recommendations and strategies may fail to consider female-specific adaptations and hormone responses, such as monthly fluctuations in estrogen and progesterone throughout the menstrual cycle. Current CHO guidelines for female athletes and exercising women need to be audited and explored further in the literature to support female athlete health and performance.

Review of the scientific rationale, development and validation of the International Olympic Committee Relative Energy Deficiency in Sport Clinical Assessment Tool: V.2 (IOC REDs CAT2)-by a subgroup of the IOC consensus on REDs.

Relative Energy Deficiency in Sport (REDs) has various different risk factors, numerous signs and symptoms and is heavily influenced by one's environment. Accordingly, there is no singular validated diagnostic test. This 2023 International Olympic Committee's REDs Clinical Assessment Tool-V.2 (IOC REDs CAT2) implements a three-step process of: (1) initial screening; (2) severity/risk stratification based on any identified REDs signs/symptoms (primary and secondary indicators) and (3) a physician-led final diagnosis and treatment plan developed with the athlete, coach and their entire health and performance team. The CAT2 also introduces a more clinically nuanced four-level traffic-light (green, yellow, orange and red) severity/risk stratification with associated sport participation guidelines. Various REDs primary and secondary indicators have been identified and 'weighted' in terms of scientific support, clinical severity/risk and methodological validity and usability, allowing for objective scoring of athletes based on the presence or absence of each indicator. Early draft versions of the CAT2 were developed with associated athlete-testing, feedback and refinement, followed by REDs expert validation via voting statements (ie, online questionnaire to assess agreement on each indicator). Physician and practitioner validity and usability assessments were also implemented. The aim of the IOC REDs CAT2 is to assist qualified clinical professionals in the early and accurate diagnosis of REDs, with an appropriate clinical severity and risk assessment, in order to protect athlete health and prevent prolonged and irreversible outcomes of REDs.