Effects of reduced energy availability on bone metabolism in women and men

BACKGROUND

The short-term effects of low energy availability (EA) on bone metabolism in physically active women and men are currently unknown.

PURPOSE

We evaluated the effects of low EA on bone turnover markers (BTMs) in a cohort of women and a cohort of men, and compared effects between sexes.

METHODS

These studies were performed using a randomised, counterbalanced, crossover design. Eleven eumenorrheic women and eleven men completed two 5-day protocols of controlled (CON; 45kcal·kgLBM^-1·d^-1) and restricted (RES; 15kcal·kgLBM^-1·d^-1) EAs. Participants ran daily on a treadmill at 70% of their peak aerobic capacity (VO₂ peak) resulting in an exercise energy expenditure of 15kcal·kgLBM^-1·d^-1 and consumed diets providing 60 and 30kcal·kgLBM^-1·d^-1. Blood was analysed for BTMs [β-carboxyl-terminal cross-linked telopeptide of type I collagen (β-CTX) and amino-terminal propeptide of type 1 procollagen (P1NP)], markers of calcium metabolism [parathyroid hormone (PTH), albumin-adjusted calcium (ACa), magnesium (Mg) and phosphate (PO₄)] and regulatory hormones [sclerostin, insulin-like growth factor 1 (IGF-1), triiodothyronine (T₃), insulin, leptin, glucagon-like-peptide-2 (GLP-2)].

RESULTS

In women, β-CTX AUC was significantly higher (P=0.03) and P1NP AUC was significantly lower (P=0.01) in RES compared to CON. In men, neither β-CTX (P=0.46) nor P1NP (P=0.12) AUCs were significantly different between CON and RES. There were no significant differences between sexes for any BTM AUCs (all P values>0.05). Insulin and leptin AUCs were significantly lower following RES in women only (for both P=0.01). There were no differences in any AUCs of regulatory hormones or markers of calcium metabolism between men and women following RES (all P values>0.05).

CONCLUSIONS

When comparing within groups, five days of low EA (15kcal·kgLBM^-1·d^-1) decreased bone formation and increased bone resorption in women, but not in men, and no sex specific differences were detected.

Low energy availability, menstrual dysfunction, and impaired bone health: A survey of elite para athletes

INTRODUCTION

The Female Athlete Triad (Triad) is a syndrome describing three interrelated conditions: low energy availability (LEA), menstrual dysfunction, and low bone mineral density (BMD). Relative Energy Deficiency in Sport (RED-S) expands the Triad to include multiple physiologic consequences of LEA in both sexes. The purpose of this study is to determine the prevalence of factors associated with the Triad/RED-S in an elite para athlete population.

METHODS

Athletes were U.S. elite para athletes training to qualify for the 2016 or the 2018 Paralympic Games. Participants completed an online questionnaire characterizing nutrition, menstrual status (in females), bone health, and awareness of the Triad/RED-S.

RESULTS

The athletes were 260 elite para athletes (150 male, 110 female). While few reported prior eating disorder (3.1%), 32.4% had elevated Eating Disorder Examination Questionnaire (EDE-Q) pathologic behavior subscale scores. Most athletes (95 male, 65 female) were attempting to change their body composition or weight to improve performance. Forty-four percent of premenopausal females had oligomenorrhea/amenorrhea. Bone stress injury was reported in 9.2% of athletes; of these, 54.5% (n = 12) had low BMD. Less than 10% of athletes reported awareness of the Triad/RED-S.

CONCLUSIONS

Factors associated with the Triad/RED-S are present in an elite para athlete population, regardless of sex or sport type. Awareness of the Triad/RED-S in para athletes is low. The consequences of LEA in para athlete populations are poorly understood. However, the high prevalence of factors observed suggests value in advancing screening tools and education efforts to optimize health in this population.

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.

Mapping the complexities of Relative Energy Deficiency in Sport (REDs): development of a physiological model by a subgroup of the International Olympic Committee (IOC) Consensus on REDs

The 2023 International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) notes that exposure to low energy availability (LEA) exists on a continuum between adaptable and problematic LEA, with a range of potential effects on both health and performance. However, there is variability in the outcomes of LEA exposure between and among individuals as well as the specific manifestations of REDs. We outline a framework for a 'systems biology' examination of the effect of LEA on individual body systems, with the eventual goal of creating an integrated map of body system interactions. We provide a template that systematically identifies characteristics of LEA exposure (eg, magnitude, duration, origin) and a variety of moderating factors (eg, medical history, diet and training characteristics) that could exacerbate or attenuate the type and severity of impairments to health and performance faced by an individual athlete. The REDs Physiological Model may assist the diagnosis of underlying causes of problems associated with LEA, with a personalised and nuanced treatment plan promoting compliance and treatment efficacy. It could also be used in the strategic prevention of REDs by drawing attention to scenarios of LEA in which impairments of health and performance are most likely, based on knowledge of the characteristics of the LEA exposure or moderating factors that may increase the risk of harmful outcomes. We challenge researchers and practitioners to create a unifying and dynamic physiological model for each body system that can be continuously updated and mapped as knowledge is gained.

Best practice recommendations for body composition considerations in sport to reduce health and performance risks: a critical review, original survey and expert opinion by a subgroup of the IOC consensus on Relative Energy Deficiency in Sport (REDs)

BACKGROUND

The assessment of body composition (BC) in sport raises concern for athlete health, especially where an overfocus on being lighter or leaner increases the risk of Relative Energy Deficiency in Sport (REDs) and disordered eating.

METHODS

We undertook a critical review of the effect of BC on performance (29 longitudinal, prospective or intervention studies) and explored current practice related to BC considerations via a follow-up to a 2013 internationally distributed survey.

RESULTS

The review found that a higher level of body fat was negatively associated with endurance performance, while a gain in muscle mass resulted in performance benefits across sports. BC did not contribute to early talent identification, and no unique cut-off to signify a performance advantage for BC was identified. BC appears to be one of an array of variables impacting performance, and its influence should not be overstated. The survey (125 practitioners, 61 sports and 26 countries) showed subtle changes in BC considerations over time, such as an increased role for sport dietitian/nutrition practitioners as BC measurers (2013: 54%, 2022: 78%); less emphasis on reporting of body fat percentage (2013: 68%, 2022: 46%) and reduced frequency of BC assessment if ≥every fourth week (2013: 18%, 2022: 5%). Respondents remained concerned about a problematic focus on BC (2013: 69%, 2022: 78%). To address these findings, we provide detailed recommendations for BC considerations, including an overview of preferable BC methodology.

CONCLUSIONS

The 'best practice' guidelines stress the importance of a multidisciplinary athlete health and performance team, and the treatment of BC data as confidential medical information. The guidelines provide a health focus around BC, aiming to reduce the associated burden of disordered eating, problematic low energy availability and REDs.

Intersection of mental health issues and Relative Energy Deficiency in Sport (REDs): a narrative review by a subgroup of the IOC consensus on REDs

Overall athlete health is a stated priority by the International Olympic Committee (IOC), yet it can be difficult for athletes to safely balance nutritional needs, training load, recovery, social interactions, expectations and other demands. The effect of energy intake and, especially, low energy availability (LEA) on athlete mental health, is understudied. In this narrative review, we examine research that has included psychological factors and mental health variables when investigating the effect of LEA, dieting/restrictive eating and Relative Energy Deficiency in Sport (REDs), since the 2018 IOC consensus statement on REDs. Based on currently available data, early psychological indicators associated with problematic LEA are mood changes, fatigue and psychological conflict. More severe mental health outcomes associated with REDs are reduced well-being, elevated anxiety, depressive symptoms and eating disorders. We propose a psychological model that helps structure how possible risk factors (eg, body dissatisfaction, environmental demands or increased training load) and moderating (eg, gender, sport) and/or potential mediating (eg, social climate, self-esteem) factors are associated with LEA and ultimately REDs. The current scientific literature underscores the importance of including mental health factors when screening for REDs and for developing a clinical approach to address the psychological sequelae of REDs once diagnosed. An interdisciplinary perspective is recommended. Lastly, and importantly, the athlete perspective urges clinicians to not underestimate the drive for success and denial of health consequences that athletes demonstrate when pursuing their sport goals.

Boston Marathon athlete performance outcomes and intra-event medical encounter risk associated with low energy availability indicators

OBJECTIVE

To determine the association between survey-based self-reported problematic low energy availability indicators (LEA-I) and race performance and intra-event medical encounters during the Boston Marathon.

METHODS

1030 runners who were registered for the 2022 Boston Marathon completed an electronic survey (1-4 weeks pre-race) assessing LEA-I, training and medical history. De-identified survey data were linked to event wearable timing chips and medical encounter records. LEA-I was defined as: an elevated Eating Disorder Examination Questionnaire score, elevated Low Energy Availability (LEA) in Females Questionnaire score, LEA in Males Questionnaire with a focus on gonadal dysfunction score and/or self-report of diagnosed eating disorder/disordered eating.

RESULTS

The prevalence of LEA-I was 232/546 (42.5%) in females and 85/484 (17.6%) in males. Athletes without LEA-I (non-LEA-I) achieved significantly better race times versus those with LEA-I (accounting for demographic and anthropomorphic data, training history and marathon experience), along with better division finishing place (DFP) mean outcomes (women's DFP: 948.9±57.6 versus 1377.4±82.9, p<0.001; men's DFP: 794.6±41.0 versus 1262.4±103.3, p<0.001). Compared with non-LEA-I athletes, LEA-I athletes had 1.99-fold (95% CI: 1.15 to 3.43) increased relative risk (RR) of an intra-event medical encounter of any severity level, and a 2.86-fold increased RR (95% CI:1.31 to 6.24) of a major medical encounter.

CONCLUSION

This is the largest study to link LEA-I to intra-event athletic performance and medical encounters. LEA-I were associated with worse race performance and increased risk of intra-event medical encounters, supporting the negative performance and medical risks associated with problematic LEA-I in marathon athletes.

Current Resting Metabolic Rate Prediction Equations Lack Sensitivity and Specificity to Indicate Relative Energy Deficiency in Sport: A Large Cohort Study in Elite Athletes

OBJECTIVES

Measured resting metabolic rate (RMR) was compared to predicted RMR equations (RMRratio) to see whether a low RMRratio relates to the Relative Energy Deficiency in Sport (REDs) Clinical Assessment Tool 2 (CAT2) severity/risk score.

METHODS

Female (n = 127) and male (n = 53) athletes (performance Tiers 3-5) were assigned green/yellow/orange/red light according to CAT2. RMR and submaximal exercise energy expenditure (via cycle ergometer) were assessed fasted on the same morning via indirect calorimetry. Low RMR was defined as RMRratio < 0.90, with 11 RMR prediction equations tested for sensitivity, specificity, and predictive validity against the CAT2.

RESULTS

RMRratio (Cunningham) was only lower in red versus green light (0.90 ± 0.07 vs. 0.99 ± 0.10; p = .023; but RMRratio was only low in 44% of red light athletes). The prevalence of low RMRratio ranged from 1% (Owen equation) to 68% (van Hooren equation) despite the overall prevalence of REDs being 46%. As a diagnostic (no REDs [green] vs. REDs [yellow + orange + red]), Cunningham equation reported sensitivity (true positives) of 0.77 at RMRratio of 1.00 and specificity (true negatives) of 1.00 at RMRratio of 0.70. Exercise energy expenditure was significantly lower in green versus orange (0.131 ± 0.013 vs. 0.142 ± 0.008 kcal·kg fat-free mass-1·min-1; p < .001) but was greater in red (0.127 ± 0.011) versus orange.

CONCLUSION

Interpretation of RMRratio is radically impacted by choice of prediction equation. Although there may be some utility in cross-sectionally detecting extreme REDs cases (red light) via RMRratio, more research with a focus on sport/phenotype-specific prediction equations and varying risk thresholds is required to strengthen the validity and reliability of RMR as a part of REDs diagnostics.

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.

Bringing reproductive, pelvic and breast health to light: insights from the Health of Elite Retired Australian female athletes survey (HER-Aus)

OBJECTIVES

To describe the reproductive, pelvic and breast health of retired elite Australian female athletes.

METHODS

Data were collected as part of a larger online cross-sectional survey that was cocreated with female athletes and disseminated to Australian retired elite (international-level and national-level) female athletes aged ≥18 years old and retired from elite competition ≥2 years.

RESULTS

199 retired female athletes (mean (SD) age 44 (10) years; retired for 16 (9) years; competed for 10 (5) years) across 31 different sports responded to the survey. 23% (46/199) experienced primary amenorrhoea, and 48% (95/197) reported ever experiencing secondary amenorrhoea. Of athletes with pregnancy difficulties (n=45), 42% reported menstrual cycle irregularity during their career. Of athletes who gave birth (n=98), 19% had difficulties conceiving, requiring fertility treatments. The majority of athletes reported current symptoms of urinary incontinence (70% (140/198)) and faecal incontinence (54% (106/197)). 18% (33/188) reported that they currently experience exercise-related breast pain; however, 87% (164/188) reported that breast pain never negatively impacts their current physical activity.

CONCLUSIONS

A high prevalence of reported menstrual irregularities, pelvic floor dysfunction and fertility issues highlights the need for early prevention and intervention measures to address long-term health and the unique challenges faced by female athletes during and after their sporting careers.

Reproductive Health Management of Female Adolescent Athletes With Relative-Energy Deficiency in Sport

The objective of this document is to guide the screening, diagnosis, and management of Relative Energy Deficiency in Sport (RED-S) in Adolescent/Young Adult (AYA) athletes to treat symptoms and reduce long-term sequelae with a focus on gynecologic aspects of the disorder. RED-S is a more comprehensive term for the condition previously known as the Female Athlete Triad. An overview of the clinical presentation, evaluation, and management of the reproductive health aspects of RED-S for female athletes is provided. For the purposes of this document, "female" refers to those designated female at birth, and "athlete" is defined as an individual who participates in regular physical activity. This document is intended for use by healthcare providers who care for female AYA athletes with RED-S.

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.