Body Composition, Energy Availability, Training, and Menstrual Status in Female Runners

Dietary habits and knee and shoulder injury incidence in adolescent male and female handball players: the Swedish Handball Cohort

Objectives

To assess the association between (1) dietary habits and knee/shoulder injury incidence in male and female adolescent handball players and (2) menstrual dysfunction and injury incidence in females.

Methods

This study is based on seasons 2020-2022 of the Swedish Handball Cohort including 1144 participants (1703 player seasons) free from a substantial knee and shoulder injury. Participants self-reported meal frequency, meal timing, nutritional intake and menstrual function (season 2022/2023) at baseline. Weekly follow-ups throughout the season assessed training and matches, and substantial knee/shoulder injuries. Cox regression analyses estimated a hazard rate ratio (HRR) with the first event of a knee/shoulder injury (combined), with minutes of handball training and matches as the timescale.

Results

In females, adjusted analyses generated an HRR for knee/shoulder injuries of 1.46 (95% CI 1.08, 1.98) for moderate-high nutritional quality compared with low quality and an HRR of 1.38 (95% CI 1.02, 1.86) for ≥2 unfavourable dietary habits compared with 1 unfavourable dietary habit. For poor meal timing, adjusted analyses generated an HRR of 1.20 (95% CI 0.90, 1.61) compared with adequate timing in females. In males, adjusted analyses generated an HRR of 1.23 (95% CI 0.69, 2.17) for low meal frequency and an HRR of 0.83 (95% CI 0.60, 1.15) for poor meal timing.

Conclusions

In adolescent female handball players, moderate-high nutritional quality and ≥2 unfavourable dietary habits are associated with higher knee/shoulder injury incidence; whereas, no or unprecise associations were found for other dietary habits in females and males and for menstrual dysfunction in females.

Diet, risk of disordered eating and running-related injury in adult distance runners: A systematic review and meta-analysis of prospective cohort studies

OBJECTIVES

To determine whether diet and disordered eating risk contribute to running-related injury risk in adult (≥18 years) distance runners.

DESIGN

Systematic review and meta-analysis.

METHODS

Random effects meta-analyses of prospective cohort studies compared dietary intake and disordered eating risk in distance runners with and without running-related injury. Quality of evidence was assessed using an adapted Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Fifteen studies (n = 5942 runners, 2364 female) were included, with nine studies in the meta-analyses. Sex differences were observed for total energy and total fat intake (both p = 0.01). Moderate certainty evidence indicated injured female runners had lower energy and fat intake than uninjured runners (mean difference [95 % confidence interval] = -449 kcal/day [-696, -202] and -20 g/day [-31, -9], respectively, both p < 0.001). Moderate certainty evidence suggested injured runners (combined sexes) had lower dietary fibre intake compared to uninjured runners (-3 g/day [-5, -0], p = 0.04). Other dietary factors (protein, carbohydrate, calcium, alcohol intake and disordered eating risk) did not influence injury risk (low-moderate certainty evidence).

CONCLUSIONS

Moderate certainty evidence indicates female distance runners with lower energy and total fat intakes are at increased risk of running-related injury, as are runners (combined sexes) with lower dietary fibre intake. Future research should include long duration, high quality prospective cohort studies in male and female runners with clearly defined athletic abilities, consistent injury definition, and standardised statistical analyses.

REVIEW REGISTRATION

PROSPERO # CRD42022323627.

Risk of Low Energy Availability, Disordered Eating, and Menstrual Dysfunction in Female Collegiate Runners

CONTEXT

Collegiate female distance runners may be at risk for low energy availability (LEA) due to increased exercise energy expenditure with or without decreased energy intake. Furthermore, this population has an increased risk of disordered eating (DE), which can lead to LEA and negative health consequences, such as menstrual dysfunction (MD).

OBJECTIVE

To (1) investigate risk of LEA, DE, and MD; (2) compare DE, training volume, and weight dissatisfaction between female collegiate runners at risk and those not at risk for LEA; and (3) compare the risk for LEA between National Collegiate Athletic Association Division I, II, and III female collegiate runners.

DESIGN

Cross-sectional study.

SETTING

Free-living conditions.

PATIENTS OR OTHER PARTICIPANTS

A total of 287 female runners who competed on a National Collegiate Athletic Association Division I, II, or III cross-country team, track team, or both.

MAIN OUTCOME MEASURE(S)

Participants completed a 45-item questionnaire that included the Low Energy Availability in Females Questionnaire (LEAF-Q) and the Disordered Eating Screen for Athletes (DESA-6).

RESULTS

We observed that 54.4% (n = 156) of runners were at risk for LEA (LEAF-Q score ≥ 8), 40.8% (n = 117) were at risk for DE (DESA-6 score ≥ 3), and 56.5% (n = 162) reported MD (LEAF-Q menstrual function subsection score ≥ 4). Athletes at risk for LEA had higher DESA-6 scores than athletes not at risk for LEA (P < .001). Athletes at risk for LEA had greater weight dissatisfaction than those not at risk for LEA ( = 15.92, P = .001). Higher weekly training volume was not associated with risk for LEA ( = 4.20, P = .11).

CONCLUSIONS

A substantial percentage of collegiate female runners were found to be at risk for LEA and DE and to report MD. These findings demonstrate that the risks for DE, MD, and weight dissatisfaction are associated with risk for LEA.

The race within a race: Together on the marathon starting line but miles apart in the experience

Every four years the world's best athletes come together to compete in the Olympic games, electrifying audiences with incredible feats of speed, strength, endurance and skill as personal best performances and new records are set. However, the exceptional talent that underpin such performances is incomprehensible to most casual observers who often cannot appreciate how unique these athletes are. In this regard, endurance running, specifically the marathon, a 42.195 km foot race, provides one of the few occasions in sport outside of Olympic, world and national competitions, that permits sport scientists and fans alike to directly compare differences in the physiology between recreational and elite competitors. While these individuals may all cover the same distance, on the same course, on the same day - their experience and the physiological and psychological demands placed upon them are vastly different. There is, in effect, a "race within a race". In the current review we highlight the superior physiology of the elite endurance athlete, emphasizing the gap between elite competitors and well-trained, but less genetically endowed athletes. We draw attention to a range of inconsistencies in how current sports science practices are understood, implemented, and communicated in terms of the elite and not-so-elite endurance athlete.

Beyond Menstrual Dysfunction: Does Altered Endocrine Function Caused by Problematic Low Energy Availability Impair Health and Sports Performance in Female Athletes?

Low energy availability, particularly when problematic (i.e., prolonged and/or severe), has numerous negative consequences for health and sports performance as characterized in relative energy deficiency in sport. These consequences may be driven by disturbances in endocrine function, although scientific evidence clearly linking endocrine dysfunction to decreased sports performance and blunted or diminished training adaptations is limited. We describe how low energy availability-induced changes in sex hormones manifest as menstrual dysfunction and accompanying hormonal dysfunction in other endocrine axes that lead to adverse health outcomes, including negative bone health, impaired metabolic activity, undesired outcomes for body composition, altered immune response, problematic cardiovascular outcomes, iron deficiency, as well as impaired endurance performance and force production, all of which ultimately may influence athlete health and performance. Where identifiable menstrual dysfunction indicates hypothalamic-pituitary-ovarian axis dysfunction, concomitant disturbances in other hormonal axes and their impact on the athlete's health and sports performance must be recognized as well. Given that the margin between podium positions and "losing" in competitive sports can be very small, several important questions regarding low energy availability, endocrinology, and the mechanisms behind impaired training adaptations and sports performance have yet to be explored.

Running Event, Age, and Competitive Level as Predictors of Dual-Energy X-Ray Absorptiometry-Derived Body Composition and Bone Health Markers in Female Runners

ABSTRACT

Wilson, LJ and Curtis, C. Running event, age, and competitive level as predictors of dual-energy X-ray absorptiometry-derived body composition and bone health markers in female runners. J Strength Cond Res 38(7): e366-e372, 2024-The aim of this study was to assess the impact of running discipline, competitive level (COMP), and age on body composition measures in female athletes. A total of n = 51 female runners (age: 30.9 ± 5.7 years, stature: 166.7 ± 5.7 cm, and body mass (BM): 57.1 ± 8.2 kg) completed a full-body dual-energy x-ray absorptiometry (DXA) scan in a cross-sectional design. One-way ANOVA or Kruskal-Wallis was used to identify differences in DXA measures and independent variables. Stepwise regression determined the contribution of independent variables on DXA measures. Body fat percentage (BF%) and fat mass (FM) differed based on COMP (BF%: H (2) = 17.451; FM: H (2) = 17.406, both p ≤ 0.0001). Competitive level modestly predicted BF% and FM (BF%: R2adj = 0.316, F (1,50) = 22.660; FM: R2adj = 0.300, F (1,50) = 21.029, both p ≤ 0.0001). Bone mineral density (BMD) and BMD Z-score (BMD Z ) did not differ between age, running discipline, or COMP (age: BMD: F (2,50) = 2.825, BMD Z : F (2,50) = 2.215; running discipline: BMD: F (3,50) = 1.145, BMD Z : F (3,50) = 1.474; COMP: BMD: F (2,50) = 0.074, BMD Z : F (2,50) = 1.297, all p ≤ 0.05). Age and running discipline modestly predicted BMD and BMD Z (BMD: R2adj = 0.179, F (1,50) = 5.264; BMD Z : R2adj = 0.173, F (1,50) = 4.545, both p ≤ 0.05). These findings indicate COMP may be a predictor of BF% and FM. Age and running discipline appear predictors of bone health markers. Such findings may enable medical and sport science practitioners to tailor interventions relating to realization of training adaptations, performance, and health.

Direct and indirect impact of low energy availability on sports performance

Low energy availability (LEA) occurs inadvertently and purposefully in many athletes across numerous sports; and well planned, supervised periods with moderate LEA can improve body composition and power to weight ratio possibly enhancing performance in some sports. LEA however has the potential to have negative effects on a multitude of physiological and psychological systems in female and male athletes. Systems such as the endocrine, cardiovascular, metabolism, reproductive, immune, mental perception, and motivation as well as behaviors can all be impacted by severe (serious and/or prolonged or chronic) LEA. Such widely diverse effects can influence the health status, training adaptation, and performance outcomes of athletes leading to both direct changes (e.g., decreased strength and endurance) as well as indirect changes (e.g., reduced training response, increased risk of injury) in performance. To date, performance implications have not been well examined relative to LEA. Therefore, the intent of this narrative review is to characterize the effects of short-, medium-, and long-term exposure to LEA on direct and indirect sports performance outcomes. In doing so we have focused both on laboratory settings as well as descriptive athletic case-study-type experiential evidence.

Effects of a training intervention tailored to the menstrual cycle on endurance performance and hemodynamics

BACKGROUND

This study aimed to compare the effects of block periodized training and training adapted to the menstrual cycle (MC) phases on endurance performance, cardiovascular parameters, recovery, and MC-related symptoms in active females.

METHODS

Fourteen naturally menstruating, moderately trained females (age: 24±3 years; BMI: 22.3±2.7) were randomized into an intervention (INT) and a control (CON) group. Throughout an 8-week intervention period, both groups participated in a polarized training program. In the INT, the training sessions were adapted to the MC with higher training loads within the mid and late follicular phase. Before and after the intervention maximal oxygen consumption (VO2max), velocity and heart rate at ventilatory thresholds one and two (vVT1, vVT2, hrVT1, hrVT2), systolic and diastolic blood pressure (sBP, dBP), root mean square of successive RR interval differences (RMSSD), standard deviation of NN intervals (SDNN), pulse wave velocity (PWV), and the premenstrual assessment form (PAF) were assessed.

RESULTS

There were no significant time × group interaction effects in all physiological parameters (VO2max: P=0.890; vVT1: P=1.000; hrVT1: P=0.464; vVT2: P=0.356; hrVT2: P=0.762 sBP: P=0.948; dBP: P=0.203; RMSSD: P=0.257; SDNN: P=0.241; PWV: P=0.818), or psychological parameters (PAF: P=0.745).

CONCLUSIONS

Tailoring a polarized training program to the MC did not augment training responses compared to a regular training program in active females. However, a substantial portion of the training intervention in the CON was coincidentally matched to the MC.

The Prevalence of Menstrual Cycle Disorders and Menstrual Cycle-Related Symptoms in Female Athletes: A Systematic Literature Review

BACKGROUND

Menstrual cycle (MC) disorders and MC-related symptoms can have debilitating effects on the health and performance of female athletes. As the participation of women in sports continues to increase, understanding the prevalence of a range of MC disorders and MC-related symptoms may guide preventive strategies to protect the health and optimise the performance of female athletes.

OBJECTIVE

To examine the prevalence of MC disorders and MC-related symptoms among female athletes who are not using hormonal contraceptives and evaluate the assessment methods used to identify MC disorders and MC-related symptoms.

METHODS

This systematic review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Six databases were searched until September 2022 for all original research that reported the prevalence of MC disorders and/or MC-related symptoms in athletes not using hormonal contraceptives, which included the definitions of the MC disorders examined, and the assessment methods used. MC disorders included amenorrhoea, anovulation, dysmenorrhoea, heavy menstrual bleeding (HMB), luteal phase deficiency (LPD), oligomenorrhoea, premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). MC-related symptoms included any affective and physical symptoms related to the MC that do not cause significant personal, interpersonal or functional impairment. The prevalence data across eligible studies were combined, and all studies were qualitatively synthesised to evaluate the assessment methods and tools used to identify MC disorders and MC-related symptoms. The methodological quality of studies was assessed using a modified Downs and Black checklist.

RESULTS

Sixty studies involving 6380 athletes were included. A wide range of prevalence was observed for all types of MC disorders, with a dearth of data on anovulation and LPD. Based on pooled data, dysmenorrhoea (32.3%; range 7.8-85.6%) was the most prevalent MC disorder. Studies reporting MC-related symptoms mostly examined the premenstrual and menstruation phases, where affective symptoms appeared more prevalent than physical symptoms. A larger proportion of athletes reported symptoms during the initial days of menstruation compared with the premenstrual phase. MC disorders and MC-related symptoms were retrospectively assessed using self-report methods in 90.0% of studies. Most studies (76.7%) in this review were graded as moderate quality.

DISCUSSION

MC disorders and MC-related symptoms are commonplace among female athletes, warranting further research examining their impact on performance and preventive/management strategies to optimise athlete health. To increase the quality of future studies, researchers should adopt standardised definitions of MC disorders and assessment methods such as a combination of calendar counting, urinary ovulation tests and a mid-luteal phase serum progesterone measurement when assessing menstrual function. Similarly, standardised diagnostic criteria should be used when examining MC disorders such as HMB, PMS and PMDD. Practically, implementing prospective cycle monitoring that includes ovulation testing, mid-luteal blood sampling (where feasible) and symptom logging throughout the MC could support athletes and practitioners to promptly identify and manage MC disorders and/or MC-related symptoms.

TRIAL REGISTRATION

This review has been registered in the PROSPERO database (CRD42021268757).

2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs)

Relative Energy Deficiency in Sport (REDs) was first introduced in 2014 by the International Olympic Committee's expert writing panel, identifying a syndrome of deleterious health and performance outcomes experienced by female and male athletes exposed to low energy availability (LEA; inadequate energy intake in relation to exercise energy expenditure). Since the 2018 REDs consensus, there have been >170 original research publications advancing the field of REDs science, including emerging data demonstrating the growing role of low carbohydrate availability, further evidence of the interplay between mental health and REDs and more data elucidating the impact of LEA in males. Our knowledge of REDs signs and symptoms has resulted in updated Health and Performance Conceptual Models and the development of a novel Physiological Model. This Physiological Model is designed to demonstrate the complexity of either problematic or adaptable LEA exposure, coupled with individual moderating factors, leading to changes in health and performance outcomes. Guidelines for safe and effective body composition assessment to help prevent REDs are also outlined. A new REDs Clinical Assessment Tool-Version 2 is introduced to facilitate the detection and clinical diagnosis of REDs based on accumulated severity and risk stratification, with associated training and competition recommendations. Prevention and treatment principles of REDs are presented to encourage best practices for sports organisations and clinicians. Finally, methodological best practices for REDs research are outlined to stimulate future high-quality research to address important knowledge gaps.

Methodology for studying Relative Energy Deficiency in Sport (REDs): a narrative review by a subgroup of the International Olympic Committee (IOC) consensus on REDs

In the past decade, the study of relationships among nutrition, exercise and the effects on health and athletic performance, has substantially increased. The 2014 introduction of Relative Energy Deficiency in Sport (REDs) prompted sports scientists and clinicians to investigate these relationships in more populations and with more outcomes than had been previously pursued in mostly white, adolescent or young adult, female athletes. Much of the existing physiology and concepts, however, are either based on or extrapolated from limited studies, and the comparison of studies is hindered by the lack of standardised protocols. In this review, we have evaluated and outlined current best practice methodologies to study REDs in an attempt to guide future research.This includes an agreement on the definition of key terms, a summary of study designs with appropriate applications, descriptions of best practices for blood collection and assessment and a description of methods used to assess specific REDs sequelae, stratified as either Preferred, Used and Recommended or Potential Researchers can use the compiled information herein when planning studies to more consistently select the proper tools to investigate their domain of interest. Thus, the goal of this review is to standardise REDs research methods to strengthen future studies and improve REDs prevention, diagnosis and care.

Symptoms of eating disorders and low energy availability in recreational active female runners

Objectives

This retrospective, cross-sectional study aimed to investigate symptoms of eating disorders (EDs) and low energy availability (LEA) among recreational female runners.

Methods

Females (18-39 years) (n=89) participating in running group sessions organised by running clubs and companies were recruited via social media and completed an anonymous online survey compromising the Eating Disorder Examination Questionnaire (EDE-Q) and Low Energy Availability in Females Questionnaire (LEAF-Q). An EDE-Q global score ≥2.3 and a LEAF-Q total score ≥8 (in combination with an injury score≥2 and/or menstruation dysfunction score≥4) were used to categorise subjects as having symptoms of EDs and LEA, respectively.

Results

Among the subjects fulfilling the age criteria (n=85), 18% (n=15) had symptoms of EDs and 19% (n=16) had symptoms of LEA. Of those with symptoms of EDs, 13% (n=2) had concomitant symptoms of LEA. The higher the EDE-Q dietary restraint score, the higher the gastrointestinal problem score (r=0.23, p=0.04), otherwise no other associations were found between EDE-Q global or subscale scores and LEAF-Q scores.

Conclusion

Our results indicate that symptoms of EDs and LEA are frequent among adult females at all athletic levels, including the recreational level. Hence, to prevent the negative health consequences of EDs and LEA, preventative initiatives are also needed in recreational running communities.

Carbohydrate intake in young female cross-country skiers is lower than recommended and affects competition performance

Purpose

(1) To evaluate if energy availability (EA), macronutrient intake and body composition change over four training periods in young, highly trained, female cross-country skiers, and (2) to clarify if EA, macronutrient intake, body composition, and competition performance are associated with each other in this cohort.

Methods

During a one-year observational study, 25 female skiers completed 3-day food and training logs during four training periods: preparation, specific preparation, competition, and transition periods. A body composition measurement (bioimpedance analyzer) was performed at the end of the preparation, specific preparation, and competition periods. Competition performance was determined by International Ski Federation (FIS) points gathered from youth national championships.

Results

EA (36-40 kcal·kg FFM^-1·d^-1) and carbohydrate (CHO) intake (4.4-5.1 g·kg^-1·d^-1) remained similar, and at a suboptimal level, between training periods despite a decrease in exercise energy expenditure (p = 0.002) in the transition period. Higher EA (r = -0.47, p = 0.035) and CHO intake (r = -0.65, p = 0.002) as well as lower FM (r = 0.60, p = 0.006) and F% (r = 0.57, p = 0.011) were associated with lower (better) FIS-points. CHO intake was the best predictor of distance competition performance (R² = 0.46, p = 0.004).

Conclusions

Young female cross-country skiers had similar EA and CHO intake over four training periods. Both EA and CHO intake were at suboptimal levels for performance and recovery. CHO intake and body composition are important factors influencing competition performance in young female cross-country skiers.

Dietary Intake, Serum Hormone Concentrations, Amenorrhea and Bone Mineral Density of Physique Athletes and Active Gym Enthusiasts

As the diet, hormones, amenorrhea, and bone mineral density (BMD) of physique athletes (PA) and gym enthusiasts (GE) are little-explored, we studied those in 69 females (50 PA, 19 GE) and 20 males (11 PA, 9 GE). Energy availability (EA, kcal·kgFFM−1·d−1 in DXA) in female and male PA was ~41.3 and ~37.2, and in GE ~39.4 and ~35.3, respectively. Low EA (LEA) was found in 10% and 26% of female PA and GE, respectively, and in 11% of male GE. In PA, daily protein intake (g/kg body mass) was ~2.9−3.0, whereas carbohydrate and fat intakes were ~3.6−4.3 and ~0.8−1.0, respectively. PA had higher protein and carbohydrate and lower fat intakes than GE (p < 0.05). Estradiol, testosterone, IGF-1, insulin, leptin, TSH, T4, T3, cortisol, or BMD did not differ between PA and GE. Serum IGF-1 and leptin were explained 6% and 7%, respectively, by EA. In non-users of hormonal contraceptives, amenorrhea was found only in PA (27%) and was associated with lower fat percentage, but not EA, BMD, or hormones. In conclusion, off-season dietary intakes, hormone levels, and BMD meet the recommendations in most of the PA and GE. Maintaining too-low body fat during the off-season may predispose to menstrual disturbances.

Energy Availability Over One Athletic Season: An Observational Study Among Athletes From Different Sports

During the athletic season, changes in body composition occur due to fluctuations in energy expenditure and energy intake. Literature regarding changes of energy availability (EA) is still scarce. The aim was to estimate EA of athletes from nonweight and weight-sensitive sports during the athletic season (i.e., preparatory and competitive phase). Eighty-eight athletes (19.1 ± 4.2 years, 21.8 ± 2.0 kg/m2, 27% females, self-reported eumenorrheic) from five sports (basketball [n = 29]; handball [n = 7]; volleyball [n = 9]; swimming [n = 18]; and triathlon [n = 25]) were included in this observational study. Energy intake and exercise energy expenditure were measured through doubly labeled water (over 7 days and considering neutral energy balance) and metabolic equivalents of tasks, respectively. Fat-free mass (FFM) was assessed through a four-compartment model. EA was calculated as EA = (energy intake - exercise energy expenditure)/FFM. Linear mixed models, adjusted for sex, were performed to assess EA for the impact of time by sport interaction. Among all sports, EA increased over the season: basketball, estimated mean (SE): 7.2 (1.5) kcal/kg FFM, p < .001; handball, 14.8 (2.9) kcal/kg FFM, p < .001; volleyball, 7.9 (2.8) kcal/kg FFM, p = .006; swimming, 8.7 (2.0) kcal/kg FFM, p < .001; and triathlon, 9.6 (2.0) kcal/kg FFM, p < .001. Eleven athletes (12.5%) had clinical low EA at the preparatory phase and none during the competitive phase. During both assessments, triathletes' EA was below optimal, being lower than basketballers (p < .001), volleyballers (p < .05), and swimmers (p < .001). Although EA increased in all sports, triathlon's EA was below optimal during both assessments. Risk of low EA might be seasonal and resolved throughout the season, with higher risk during the preparatory phase. However, in weight-sensitive sports, namely triathlon, low EA is still present.

Markers of Low Energy Availability in Overreached Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Overreaching is the transient reduction in performance that occurs following training overload and is driven by an imbalance between stress and recovery. Low energy availability (LEA) may drive underperformance by compounding training stress; however, this has yet to be investigated systematically.

OBJECTIVE

The aim of this study was to quantify changes in markers of LEA in athletes who demonstrated underperformance, and exercise performance in athletes with markers of LEA.

METHODS

Studies using a ≥ 2-week training block with maintained or increased training loads that measured exercise performance and markers of LEA were identified using a systematic search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Changes from pre- to post-training were analyzed for (1) markers of LEA in underperforming athletes and (2) performance in athletes with ≥ 2 markers of LEA.

RESULTS

From 56 identified studies, 14 separate groups of athletes demonstrated underperformance, with 50% also displaying ≥ 2 markers of LEA post-training. Eleven groups demonstrated ≥ 2 markers of LEA independent of underperformance and 37 had no performance reduction or ≥ 2 markers of LEA. In underperforming athletes, fat mass (d =  - 0.29, 95% confidence interval [CI] - 0.54 to - 0.04; p = 0.02), resting metabolic rate (d =  - 0.63, 95% CI - 1.22 to - 0.05; p = 0.03), and leptin (d =  - 0.72, 95% CI - 1.08 to - 0.35; p < 0.0001) were decreased, whereas body mass (d =  - 0.04, 95% CI - 0.21 to 0.14; p = 0.70), cortisol (d =  - 0.06, 95% CI - 0.35 to 0.23; p = 0.68), insulin (d =  - 0.12, 95% CI - 0.43 to 0.19; p = 0.46), and testosterone (d =  - 0.31, 95% CI - 0.69 to 0.08; p = 0.12) were unaltered. In athletes with ≥ 2 LEA markers, performance was unaffected (d = 0.09, 95% CI - 0.30 to 0.49; p = 0.6), and the high heterogeneity in performance outcomes (I² = 84.86%) could not be explained by the performance tests used or the length of the training block.

CONCLUSION

Underperforming athletes may present with markers of LEA, but overreaching is also observed in the absence of LEA. The lack of a specific effect and high variability of outcomes with LEA on performance suggests that LEA is not obligatory for underperformance.

Risk of Low Energy Availability, Disordered Eating, Exercise Addiction, and Food Intolerances in Female Endurance Athletes

Relative energy deficiency in sport (RED-S) is a complex syndrome describing health and performance consequences of low energy availability (LEA) and is common among female endurance athletes. Various underlying causes of LEA have been reported, including disordered eating behavior (DE), but studies investigating the association with exercise addiction and food intolerances are lacking. Therefore, the aim of this cross-sectional study was to investigate the association between DE, exercise addiction and food intolerances in athletes at risk of LEA compared to those with low risk. Female endurance athletes, 18-35 years, training ≥5 times/week were recruited in Norway, Sweden, Ireland, and Germany. Participants completed an online-survey comprising the LEA in Females Questionnaire (LEAF-Q), Exercise Addiction Inventory (EAI), Eating Disorder Examination Questionnaire (EDE-Q), and questions regarding food intolerances. Of the 202 participants who met the inclusion criteria and completed the online survey, 65% were at risk of LEA, 23% were at risk of exercise addiction, and 21% had DE. Athletes at risk of LEA had higher EDE-Q and EAI scores compared to athletes with low risk. EAI score remained higher in athletes with risk of LEA after excluding athletes with DE. Athletes at risk of LEA did not report more food intolerances (17 vs. 10%, P = 0.198), but were more frequently reported by athletes with DE (28 vs. 11%, P = 0.004). In conclusion, these athletes had a high risk of LEA, exercise addiction, and DE. Exercise addiction should be considered as an additional risk factor in the prevention, early detection, and targeted treatment of RED-S among female endurance athletes.

A Life History Perspective on Athletes with Low Energy Availability

The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy-and responds to low energy availability-is an evolved trait. Energy is a finite resource that must be distributed throughout the body to simultaneously fuel all biological processes. When energy availability is low, insufficient energy may be available to equally support all processes. As energy used for one function cannot be used for others, energetic "trade-offs" will arise. Biological processes offering the greatest immediate survival value will be protected, even if this results in energy being diverted away from others, potentially leading to their downregulation. Athletes with low energy availability provide a useful model for anthropologists investigating the biological trade-offs that occur when energy is scarce, while the broader conceptual framework provided by life history theory may be useful to sport and exercise researchers who investigate the influence of low energy availability on athlete health and performance. The goals of this review are: (1) to describe the core tenets of life history theory; (2) consider trade-offs that might occur in athletes with low energy availability in the context of four broad biological areas: reproduction, somatic maintenance, growth, and immunity; and (3) use this evolutionary perspective to consider potential directions for future research.

Self-Reported Restrictive Eating, Eating Disorders, Menstrual Dysfunction, and Injuries in Athletes Competing at Different Levels and Sports

The purpose of this study was to investigate the prevalence of self-reported restrictive eating, current or past eating disorder, and menstrual dysfunction and their relationships with injuries. Furthermore, we aimed to compare these prevalences and associations between younger (aged 15–24) and older (aged 25–45) athletes, between elite and non-elite athletes, and between athletes competing in lean and non-lean sports. Data were collected using a web-based questionnaire. Participants were 846 female athletes representing 67 different sports. Results showed that 25%, 18%, and 32% of the athletes reported restrictive eating, eating disorders, and menstrual dysfunction, respectively. Higher rates of lean sport athletes compared with non-lean sport athletes reported these symptoms, while no differences were found between elite and non-elite athletes. Younger athletes reported higher rates of menstrual dysfunction and lower lifetime prevalence of eating disorders. Both restrictive eating (OR 1.41, 95% CI 1.02–1.94) and eating disorders (OR 1.89, 95% CI 1.31–2.73) were associated with injuries, while menstrual dysfunction was associated with more missed participation days compared with a regular menstrual cycle (OR 1.79, 95% CI 1.05–3.07). Our findings indicate that eating disorder symptoms and menstrual dysfunction are common problems in athletes that should be managed properly as they are linked to injuries and missed training/competition days.

The Influence of Sport Nutrition Knowledge on Body Composition and Perceptions of Dietary Requirements in Collegiate Athletes

Sport nutrition knowledge has been shown to influence dietary habits of athletes. The purpose of the current study was to examine relationships between sport nutrition knowledge and body composition and examine potential predictors of body weight goals in collegiate athletes. Participants included National Collegiate Athletic Association Division III women (n = 42, height: 169.9 ± 6.9 cm; body mass: 67.1 ± 8.6 kg; fat-free mass: 51.3 ± 6.6 kg; body fat percent: 24.2 ± 5.3%) and men (n = 25, height: 180.8 ± 7.2 cm; body mass: 89.2 ± 20.5 kg; fat-free mass: 75.9 ± 12.2 kg; body fat percent: 13.5 ± 8.9%) athletes. Body composition was assessed via air displacement plethysmography. Athletes completed a validated questionnaire designed to assess sport nutrition knowledge and were asked questions about their perceived dietary energy and macronutrient requirements, as well as their body weight goal (i.e., lose, maintain, gain weight). Athletes answered 47.98 ± 11.29% of questions correctly on the nutrition questionnaire with no differences observed between sexes (men: 49.52 ± 11.76% vs. women: 47.03 ± 11.04%; p = 0.40). An inverse relationship between sport nutrition knowledge scores and body fat percentage (BF%) (r = −0.330; p = 0.008), and fat mass (r = −0.268; p = 0.032) was observed for all athletes. Fat mass (β = 0.224), BF% (β = 0.217), and body mass index (BMI) (β = 0.421) were all significant (p < 0.05) predictors of body weight goal in women. All athletes significantly (p < 0.001) underestimated daily energy (−1360 ± 610.2 kcal/day), carbohydrate (−301.6 ± 149.2 grams/day [g/day]), and fat (−41.4 ± 34.5 g/day) requirements. Division III collegiate athletes have a low level of sport nutrition knowledge, which was associated with a higher BF%. Women athletes with a higher body weight, BF% and BMI were more likely to select weight loss as a body weight goal. Athletes also significantly underestimated their energy and carbohydrate requirements based upon the demands of their sport, independent of sex.

Comparison of Energy Expenditure Observed between Scheduled Activities in Collegiate Team-Sport Female Athletes

Energy needs of female team-sport athletes are poorly understood with no evidence highlighting differences present between scheduled activities. The purpose of this study was to examine the difference in energy expenditure between NCAA Division II female basketball (BBALL) and lacrosse (LAX) athletes during different scheduled team activities. Female BBALL (n = 13; 19.8 ± 1.3 yrs; 173.9 ± 13.6 cm; 74.6 ± 9.1kg; 27.1 ± 3.2%fat) and LAX (n = 20; 20.4 ± 1.8yrs; 168.4 ± 6.6cm; 68.8 ± 8.9kg; 27.9 ± 3.1%fat) athletes were outfitted with heart rate and activity monitors during four consecutive days on five different occasions (20 days total) across an entire academic year to assess differences in total daily activity energy expenditure (TDEE), activity energy expenditure (AEE), and physical activity level (PAL). Data were categorized by type of scheduled daily activities: Practice, Game, Conditioning, or Off. Independent of day type, TDEE, AEE, and PAL levels were greater (p < 0.05) in BBALL athletes. For each sport, TDEE, AEE, and PAL were significantly different (p < 0.05) between classified activity days. BBALL and LAX athletes experienced higher values on game days for TDEE, AEE, and PAL, with the lowest values experienced on off days. In conclusion, calculated levels of TDEE, AEE, and PAL in female collegiate BBALL and LAX athletes were determined to be different, irrespective of the scheduled activity.