Does Relative Energy Deficiency in Sport (REDs) Syndrome Exist?

Relative energy deficiency in sport (REDs) is a widely adopted model, originally proposed by an International Olympic Committee (IOC) expert panel in 2014 and recently updated in an IOC 2023 consensus statement. The model describes how low energy availability (LEA) causes a wide range of deleterious health and performance outcomes in athletes. With increasing frequency, sports practitioners are diagnosing athletes with "REDs," or "REDs syndrome," based largely upon symptom presentation. The purpose of this review is not to "debunk" REDs but to challenge dogmas and encourage rigorous scientific processes. We critically discuss the REDs concept and existing empirical evidence available to support the model. The consensus (IOC 2023) is that energy availability, which is at the core of REDs syndrome, is impossible to measure accurately enough in the field, and therefore, the only way to diagnose an athlete with REDs appears to be by studying symptom presentation and risk factors. However, the symptoms are rather generic, and the causes likely multifactorial. Here we discuss that (1) it is very difficult to isolate the effects of LEA from other potential causes of the same symptoms (in the laboratory but even more so in the field); (2) the model is grounded in the idea that one factor causes symptoms rather than a combination of factors adding up to the etiology. For example, the model does not allow for high allostatic load (psychophysiological "wear and tear") to explain the symptoms; (3) the REDs diagnosis is by definition biased because one is trying to prove that the correct diagnosis is REDs, by excluding other potential causes (referred to as differential diagnosis, although a differential diagnosis is supposed to find the cause, not demonstrate that it is a pre-determined cause); (4) observational/cross-sectional studies have typically been short duration (< 7 days) and do not address the long term "problematic LEA," as described in the IOC 2023 consensus statement; and (5) the evidence is not as convincing as it is sometimes believed to be (i.e., many practitioners believe REDs is well established). Very few studies can demonstrate causality between LEA and symptoms, most studies demonstrate associations and there is a worrying number of (narrative) reviews on the topic, relative to original research. Here we suggest that the athlete is best served by an unbiased approach that places health at the center, leaving open all possible explanations for the presented symptoms. Practitioners could use a checklist that addresses eight categories of potential causes and involve the relevant experts if and when needed. The Athlete Health and Readiness Checklist (AHaRC) we introduce here simply consists of tools that have already been developed by various expert/consensus statements to monitor and troubleshoot aspects of athlete health and performance issues. Isolating the purported effects of LEA from the myriad of other potential causes of REDs symptoms is experimentally challenging. This renders the REDs model somewhat immune to falsification and we may never definitively answer the question, "does REDs syndrome exist?" From a practical point of view, it is not necessary to isolate LEA as a cause because all potential areas of health and performance improvement should be identified and tackled.

Energy expenditure, intake and availability in female soccer players via doubly labelled water: Are we misrepresenting low energy availability?

Female soccer players have been identified as presenting with low energy availability (LEA), though the prevalence of LEA may be overestimated given inaccuracies associated with self-reporting dietary intakes. Accordingly, we aimed to quantify total daily energy expenditure (TDEE) via the doubly labelled water (DLW) method, energy intake (EI) and energy availability (EA). Adolescent female soccer players (n = 45; 16 ± 1 years) completed a 9-10 day 'training camp' representing their national team. Absolute and relative TDEE was 2683 ± 324 and 60 ± 7 kcal kg-1 fat free mass (FFM), respectively. Mean daily EI was lower (P < 0.01) when players self-reported using the remote food photography method (RFPM) (2047 ± 383 kcal day-1) over a 3-day period versus DLW derived EI estimates accounting for body mass (BM) changes (2545 ± 518 kcal day-1) over 7-8 days, representing a mean daily Δ of 499 ± 526 kcal day-1 and 22% error when using the RFPM. Estimated EA was different (P < 0.01) between methods (DLW: 48 ± 14 kcal kg-1 FFM, range: 22-82; RFPM: 37 ± 8 kcal kg-1 FFM, range: 22-54), such that prevalence of LEA (<30 kcal kg-1 FFM) was lower in DLW compared with RFPM (5% vs. 15%, respectively). Data demonstrate the potential to significantly underestimate EI when using self-report methods. This approach can therefore cause a misrepresentation and an over-prevalence of LEA, which is the underlying aetiology of 'relative energy deficiency in sport' (REDs). HIGHLIGHTS: What is the central question of this study? Do self-reported dietary intakes (via remote food photography method, RFPM) overestimate low energy availability (LEA) prevalence in female soccer players compared with energy intake evaluation from the doubly labelled water (DLW) method? What is the main finding and its importance? Estimated energy availability is greater with the DLW method compared with RFPM, such that the prevalence of LEA is greater when self-reporting dietary intakes. Accordingly, data demonstrate the potential to misrepresent the prevalence of LEA, an underlying factor in the aetiology of 'relative energy deficiency in sport' (REDs).

A broken link: Knowledge of carbohydrate requirements do not predict carbohydrate intake around competition in endurance athletes.

Endurance athletes fail to meet carbohydrate (CHO) guidelines for competition, which may be due to limited knowledge. However, the relationship between knowledge and practice in this population is unknown. To investigate this, we assessed the dietary intake in 50 athletes (37 females) who completed endurance events ≥2.5 h in duration and compared CHO intake against the carbohydrates for endurance athletes in competition questionnaire validated nutrition knowledge questionnaire, with specific questions related to CHO loading, pre-competition meal and during-competition intake. CHO-loading guidelines (10-12 g · kg-1 · day-1) were met in practice by n = 5 (10%), but there was no relationship between identified requirements (range 0-12 g · kg-1 · day-1) and actual intake (rs = 0.133, p = 0.358), with the n = 18 (36%) who correctly identified requirements, ingesting 6.1 ± 1.9 g · kg-1 · day-1. CHO intake for pre-competition meal guidelines (1-4 g · kg-1) was met in practice by n = 40 (80%), but there was no relationship between identified requirements (range 0 to >4 g · kg-1) and actual intake (rs = 0.101, p = 0.487), with n = 19 (38%) who correctly identified guidelines requirements, ingesting 1.4 ± 0.6 g · kg-1. CHO intake during-competition guidelines (60-90 g · h-1) was met in practice by n = 18 (36%), but there was no relationship between the amounts of CHO required (range 30 to >90 g/h) and actual intake (rs = 0.028, p = 0.849), with n = 32 (64%) who correctly identified guidelines requirements, ingesting 56 ± 20 g · h-1. Results show no relationship between the knowledge of CHO recommendations and practice, suggesting that theoretical knowledge does not guarantee the achievement of best practice and other important factors may ultimately determine practice.

Energetics of a World-Tour Female Road Cyclist During a Multistage Race (Tour de France Femmes).

Despite the increased popularity of female elite road cycling, research to inform the fueling requirements of these endurance athletes is lacking. In this case study, we report for the first time the energetics of a female world-tour cyclist competing in the 2023 Tour de France Femmes, an 8-day race of the Union Cycliste Internationale. The 29-year-old athlete presented with oligomenorrhea and low T3 before the race. Total daily energy expenditure assessed with the doubly labeled water technique was 7,572 kcal/day (∼4.3 physical activity levels), among the highest reported in the literature to date for a female. Crank-based mean maximal power was consistent with female world-tour cyclists (5 min, mean 342 W, 4.8 W/kg; 20 min 289 W, 4.1 W/kg). The average daily energy intake measured with the remote food photography method (Stage Days 1-7) was 5,246 kcal and carbohydrate intake was 13.7 g/kg (range 9.7-15.9 g/kg), and 84 g/hr during stages, and an average fat intake of 15% of daily energy intake. An estimated 2,326 kcal/day energy deficit was evidenced in a 2.2 kg decrease in body mass. Notwithstanding the high carbohydrate intake, the athlete was unable to match the energy requirements of the competition. Despite signs of energy deficiency preexisting (oligomenorrhea and low T3), and other further developing during the race (weight loss), performance was in line with that of other world-tour cyclists and a best personal performance was recorded for the last stage. This case study emphasizes the need for further research to inform energy requirements for female athletes' optimal 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.

Under-Fuelling for the Work Required? Assessment of Dietary Practices and Physical Loading of Adolescent Female Soccer Players during an Intensive International Training and Game Schedule.

Previous studies demonstrate that "under-fuelling" (i.e., reduced carbohydrate (CHO) and energy intake (EI) in relation to recommended guidelines) is prevalent within adult female soccer players, the consequence of which may have acute performance and chronic health implications. However, the dietary practices of adolescent female soccer players, a population who may be particularly at risk for the negative aspects of low energy availability (LEA), are not well documented. Accordingly, we aimed to quantify EI and CHO intake, physical loading and estimated energy availability (EA) in elite national team adolescent female soccer players (n = twenty-three; age, 17.9 ± 0.5 years) during a 10-day training and game schedule comprising two match days on day six (MDa) and nine (MDb). The players self-reported their EI via the remote food photography method, whilst the physical loading and associated exercise energy expenditure were assessed via GPS technology. The relative CHO intake was significantly greater (all p < 0.05) on the day before the first match (MD-1a) (4.1 ± 0.8 g·kg-1), on the day before the second match (MD-1b) (4.3 ± 1.1 g·kg-1), MDa (4.8 ± 1.2 g·kg-1) and MDb (4.8 ± 1.4 g·kg-1) in comparison to most other days (<4 g·kg-1). The mean daily measured EA over the 10-day period was 34 ± 12 kcal·kg FFM-1·day-1 (with six players, i.e., 34%, presenting LEA), though, when adjusting the energy intake for potential under-reporting, these values changed substantially (44 ± 14 kcal·kg FFM-1·day-1, only one player was classed as presenting LEA). Such data suggest that the prevalence of LEA amongst female team sport athletes may be over-estimated. Nonetheless, players are still likely under-fuelling for the work required in relation to the daily CHO recommendations (i.e., >6 g·kg-1) for intensive training and game schedules. These data provide further evidence for the requirement to create and deliver targeted player and stakeholder education and behaviour change interventions (especially for younger athletes) that aim to promote increased daily CHO intake in female soccer players.

Mind the gap: limited knowledge of carbohydrate guidelines for competition in an international cohort of endurance athletes.

Despite the well-documented role of carbohydrate (CHO) in promoting endurance exercise performance, endurance athletes typically fail to meet current recommendations in competition. Adequate nutrition knowledge is key to drive athletes' behaviour, but the current level of knowledge in this population is not known. The present study assessed knowledge of CHO for competition in an international cohort of endurance athletes using the Carbohydrates for Endurance Athletes in Competition Questionnaire (CEAC-Q). The CEAC-Q was completed by 1016 individuals (45 % female), from the United Kingdom (40 %), Australia/New Zealand (22 %), the United States of America/Canada (18 %) and other countries (21 %). Total CEAC-Q scores were 50 ± 20 % (mean ± sd), with no differences in scores between the five subsections (10 ± 5 points, P < 0⋅001). Based on typical knowledge and frequency of correct answers, we defined questions with low (0-39 %), moderate (40-69 %) and high (70-100 %) knowledge at a population level. Knowledge deficiencies were identified in questions related to CHO metabolism (Low: 2 out of 5 questions (2/5), Moderate: 3/5), CHO-loading (Low: 2/5, Moderate: 1/5), pre-event CHO (Low: 2/5, Moderate: 2/5), CHO during exercise (Moderate: 4/5) and CHO for recovery (Low: 3/5, Moderate: 1/5). Current CHO amounts recommendations were identified correctly for CHO-loading, pre-competition meal, during competition >2⋅5 h) and post-competition recovery by 28% (Low), 45 % (Moderate), 48 % (Moderate), and 29 % (Low), respectively. Our findings indicate that endurance athletes typically have limited knowledge of carbohydrate guidelines for competition, and we identify specific knowledge gaps that can guide targeted nutrition education to improve knowledge as an initial step towards optimal dietary practice.

Physical performance during energy deficiency in humans: An evolutionary perspective.

Energy deficiency profoundly disrupts normal endocrinology, metabolism, and physiology, resulting in an orchestrated response for energy preservation. As such, despite energy deficit is typically thought as positive for weight-loss and treatment of cardiometabolic diseases during the current obesity pandemic, in the context of contemporary sports and exercise nutrition, chronic energy deficiency is associated to negative health and athletic performance consequences. However, the evidence of energy deficit negatively affecting physical capacity and sports performance is unclear. While severe energy deficiency can negatively affect physical capacity, humans can also improve aerobic fitness and strength while facing significant energy deficit. Many athletes, also, compete at an elite and world-class level despite showing clear signs of energy deficiency. Maintenance of high physical capacity despite the suppression of energetically demanding physiological traits seems paradoxical when an evolutionary viewpoint is not considered. Humans have evolved facing intermittent periods of food scarcity in their natural habitat and are able to thrive in it. In the current perspective it is argued that when facing limited energy availability, maintenance of locomotion and physical capacity are of high priority given that they are essential for food procurement for survival in the habitat where humans evolved. When energetic resources are limited, energy may be allocated to tasks essential for survival (e.g. locomotion) while minimising energy allocation to traits that are not (e.g. growth and reproduction). The current perspective provides a model of energy allocation during energy scarcity supported by observation of physiological and metabolic responses that are congruent with this paradigm.

Does eating less or exercising more to reduce energy availability produce distinct metabolic responses?

When less energy is available to consume, people often lose weight, which reduces their overall metabolic rate. Their cellular metabolic rate may also decrease (metabolic adaptation), possibly reflected in physiological and/or endocrinological changes. Reduced energy availability can result from calorie restriction or increased activity energy expenditure, raising the following question that our review explores: do the body's metabolic and physiological responses to this reduction differ or not depending on whether they are induced by dietary restriction or increased activity? First, human studies offer indirect, contentious evidence that the body metabolically adapts to reduced energy availability, both in response to either a calorie intake deficit or increased activity (exercise; without a concomitant increase in food intake). Considering individual aspects of the body's physiology as constituents of whole-body metabolic rate, similar responses to reduced energy availability are observed in terms of reproductive capacity, somatic maintenance and hormone levels. By contrast, tissue phenotypic responses differ, most evidently for skeletal tissue, which is preserved in response to exercise but not calorie restriction. Thus, while in many ways 'a calorie deficit is a calorie deficit', certain tissues respond differently depending on the energy deficit intervention. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

Protocol Standardization May Improve Precision Error of InBody 720 Body Composition Analysis.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a popular technique which can be used to track longitudinal changes in body composition. However, precision of the technique has been questioned, especially among athletic populations where small but meaningful changes are often observed. Guidelines exist which attempt to optimize precision of the technique but fail to account for potentially important variables. Standardization of dietary intake and physical activity in the 24 hr prior to assessment has been proposed as an approach to minimizing the error of impedance-derived estimates of body composition. METHODS: Eighteen recreational athletes, male (n = 10) and female (n = 8), underwent two consecutive BIA tests to quantify within-day error, and a third test (the day before or after) to quantify between-day error. All food and fluid intake plus physical activity from the 24 hr prior to the first BIA scan was replicated during the following 24 hr. Precision error was calculated as the root mean square standard deviation, percentage coefficient of variation, and least significant change. RESULTS: There were no significant differences in precision error of within- and between-day fat-free mass, fat mass, and total body water. Differences in precision error of fat-free mass and total body water, but not fat mass, were less than the smallest effect size of interest. CONCLUSION: The 24-hr standardization of dietary intake and physical activity may be an effective approach to minimizing precision error associated with BIA. However, further research to confirm the validity of this protocol compared to nonstandardized or randomized intake is warranted.

Human skeletal muscle methylome after low-carbohydrate energy-balanced exercise.

We aimed to investigate the human skeletal muscle (SkM) DNA methylome after exercise in low-carbohydrate (CHO) energy-balance (with high-fat) conditions compared with exercise in low-CHO energy-deficit (with low-fat) conditions. The objective was to identify novel epigenetically regulated genes and pathways associated with "train-low sleep-low" paradigms. The sleep-low conditions included nine males that cycled to deplete muscle glycogen while reaching a set energy expenditure. Postexercise, low-CHO meals (protein matched) completely replaced (using high fat) or only partially replaced (low fat) the energy expended. The following morning, resting baseline biopsies were taken and the participants then undertook 75 minutes of cycling exercise, with skeletal muscle biopsies collected 30 minutes and 3.5 hours postexercise. Discovery of genome-wide DNA methylation was undertaken using Illumina EPIC arrays, and targeted gene expression analysis was conducted by quantitative RT-PCR. At baseline, participants under energy balance (high fat) demonstrated a predominantly hypermethylated (60%) profile across the genome compared to energy-deficit low-fat conditions. However, postexercise performed in energy balance (with high fat) elicited a more prominent hypomethylation signature 30 minutes postexercise in gene regulatory regions important for transcription (CpG islands within promoter regions) compared with exercise in energy-deficit (with low-fat) conditions. Such hypomethylation was enriched within pathways related to IL6-JAK-STAT signaling, metabolic processes, p53/cell cycle, and oxidative/fatty acid metabolism. Hypomethylation within the promoter regions of the genes; histone deacetylase 2 (HDAC2), MECR, IGF2, and c13orf16 were associated with significant increases in gene expression in the postexercise period in energy balance compared with an energy deficit. Furthermore, HDAC11 was oppositely regulated at the gene expression level compared with family member HDAC2, where HDAC11 was hypomethylated yet increased in energy-deficit compared with energy-balance conditions. Overall, we identify some novel epigenetically regulated genes associated with train-low sleep-low paradigms.NEW & NOTEWORTHY We identify novel epigenetically regulated genes associated with train-low sleep-low paradigms. Exercise under low-carbohydrate (CHO) energy-balance (high-fat) conditions elicited a more prominent DNA hypomethylation signature 30 minutes postexercise compared with low-CHO energy-deficit (low-fat) conditions. This was enriched within IL6-JAK-STAT signaling, metabolic processes, p53, cell cycle, oxidative phosphorylation, and fatty acid metabolism. Histone deacetylase (HDAC) family members 2, 4, 10, and 11 demonstrated hypomethylation, with HDAC2 and HDAC11 possessing alternative regulation of gene expression in energy balance versus deficit conditions.

Impact of 24-Hr Diet and Physical Activity Control on Short-Term Precision Error of Dual-Energy X-Ray Absorptiometry Physique Assessment.

Dual-energy X-ray absorptiometry (DXA) is a popular technique used to quantify physique in athletic populations. Due to biological variation, DXA precision error (PE) may be higher than desired. Adherence to standardized presentation for testing has shown improvement in consecutive-day PE. However, the impact of short-term diet and physical activity standardization prior to testing has not been explored. This warrants investigation, given the process may reduce variance in total body water and muscle solute, both of which can have high daily flux amongst athletes. Twenty (n = 10 males, n = 10 females) recreationally active individuals (age: 30.7 ± 7.5 years; stature: 176.4 ± 9.1 cm; mass: 74.6 ± 14.3 kg) underwent three DXA scans; two consecutive scans on 1 day, and a third either the day before or after. In addition to adhering to standardized presentation for testing, subjects recorded all food/fluid intake plus activity undertaken in the 24 hr prior to the first DXA scan and replicated this the following 24 hr. International Society of Clinical Densitometry recommended techniques were used to calculate same- and consecutive-day PE. There was no significant difference in PE of whole-body fat mass (479 g vs. 626 g) and lean mass (634 g vs. 734 g) between same- and consecutive-day assessments. Same- and consecutive-day PE of whole-body fat mass and lean mass were less than the smallest effect size of interest. Inclusion of 24-hr standardization of diet and physical activity has the potential to reduce biological error further, but this needs to be verified with follow-up investigation.

Normalising the conversation: a qualitative analysis of player and stakeholder perceptions of menstrual health support within elite female soccer.

PURPOSE: This qualitative study explores player and stakeholder perceptions of menstrual health support in elite female soccer. METHODS: Semi-structured interviews were conducted with 47 participants including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). RESULTS: Via thematic analysis, data demonstrate that elite female soccer players experience a range of physical and psychological symptoms primarily at the onset of and during menses (as also perceived by stakeholders), with most participants perceiving these symptoms to impact performance. Nonetheless, menstrual health support is perceived as minimal and although players have their menstrual status tracked, they report little understanding as to why or how this information is used. This confusion was also present among stakeholders, often as a result of uncertainty about the evidence supporting the need for menstrual health support. The perceived lack of support may also be reflective of a culture where conversations about the menstrual cycle are not normalised. Overall, this may result in failure to identify and treat menstrual irregularities despite non-coaching staff members perceiving them to be common amongst players. CONCLUSION: These data support the need for individualised support based on the lived experiences of individual players and support staff. Furthermore, our research identifies the need for organisational, stakeholder, and player centred education programmes (led by experts in female athlete health) that create an environment where players receive personalised menstrual health support.

Patterns of energy availability of free-living athletes display day-to-day variability that is not reflected in laboratory-based protocols: Insights from elite male road cyclists.

The physiological effects of low energy availability (EA) have been studied using a homogenous daily EA pattern in laboratory settings. However, whether this daily EA pattern represents those of free-living athletes and is therefore ecologically valid is unknown. To investigate this, we assessed daily exercise energy expenditure, energy intake and EA in 10 free-living elite male road cyclists (20 min Mean Maximal Power: 5.27 ± 0.25 W · kg-1) during 7 consecutive days of late pre-season training. Energy intake was measured using the remote-food photography method and exercise energy expenditure estimated from cycling crank-based power-metres. Seven-day mean ± SD energy intake and exercise energy expenditure was 57.9 ± 10.4 and 38.4 ± 8.6 kcal · kg FFM-1 · day-1, respectively. EA was 19.5 ± 9.1 kcal · kg FFM-1 · day-1. Within-participants correlation between daily energy intake and exercise energy expenditure was .62 (95% CI: .43 - .75; P < .001), and .60 (95% CI: .41 - .74; P < .001) between carbohydrate intake and exercise energy expenditure. However, energy intake only partially compensated for exercise energy expenditure, increasing 210 kcal · day-1 per 1000 kcal · day-1 increase in expenditure. EA patterns displayed marked day-to-day fluctuation (range: -22 to 76 kcal · kg FFM-1 · day-1). The validity of research using homogenous low EA patterns therefore requires further investigation.

Ten weeks of low-volume walking training improve cardiometabolic health and body composition in sedentary postmenopausal women with obesity without affecting markers of bone metabolism.

This study aimed to determine the effects of walking exercise to induce a mild energy deficit and to improve body composition and metabolic status in postmenopausal women (PMW) with obesity as means of minimizing endocrine disruption and maintaining bone health. Twenty-four PMW with obesity (age: 55.0 ± 3.7 y, BMI: 32.9 ± 4.2 kg/m2, percent body fat: 46.2 ± 3.6%) were randomly assigned into either exercise (n = 12) or control (n = 12) groups. Exercise group participated in a-10 week supervised progressive walking programme and control group maintained regular habits. Pre- and post-training assessments included body composition, bone mass, peak oxygen uptake (V˙O2peak), osteocalcin, bone alkaline phosphatase (BAP), type I collagen cross-linked C-telopeptide (CTX)glucose, glycated haemoglobin (HbA1c)), leptin and adiponectin. Results: Following the training program, body weight (2.6%; p < 0.001), fat mass (4.5%; p = 0.002), resting glucose (6.8%; p = 0.017), and HbA1c (3.7%; p = 0.047) decreased, while relative V˙O2peak (16%; p < 0.001) increased in the exercise group. Leptin, adiponectin, CTX, osteocalcin or BAP did not change in either group. In conclusion, small dose of aerobic exercise improves key markers of metabolic health in PMW with obesity without negatively affecting markers of bone metabolism.

Carbohydrate fear, skinfold targets and body image issues: a qualitative analysis of player and stakeholder perceptions of the nutrition culture within elite female soccer.

PURPOSE: This qualitative study explores player and stakeholder perceptions of the role of nutrition in supporting player development and performance in elite female soccer. METHODS: Semi-structured interviews (36 ± 18 mins in length) were conducted with 47 participants, including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). Via thematic analysis, data provided an insight into the nutrition culture within elite women's soccer. RESULTS AND CONCLUSIONS: Data demonstrate that considerable confusion and misconceptions exist amongst players and stakeholders regarding the theoretical underpinning and practical application of meeting energy requirements. As such, it is perceived that players 'under-fuel', which is likely caused by misunderstandings about the impact of carbohydrate intake on body composition, a fear of weight gain and the associated impacts upon body image. The 'carbohydrate fear' that is experienced by players is exacerbated by external pressures arising from social media, key stakeholders (e.g., coaches) and the skinfold culture surrounding measurement of body composition. Such cultural issues are amplified by the lack of full-time professionally accredited nutritionists overseeing the provision of nutrition support. Indeed, the infrastructure supporting the women's game (e.g. staffing resource, on-site food provision, player education programmes, etc.) was considered incomparable to the men's game.When taken together, our data provide a platform for which to develop organisational, stakeholder and player centred education and behaviour change interventions that strive to promote a positive performance nutrition culture within the women's game.

A Short-Term Low-Fiber Diet Reduces Body Mass in Healthy Young Men: Implications for Weight-Sensitive Sports.

Athletes from weight-sensitive sports are reported to consume low-fiber diets (LOW) to induce acute reductions in body mass (BM). However, evidence supporting their efficacy is anecdotal. Therefore, we aimed to determine the effect of a LOW on acute changes in BM. Nineteen healthy males (32 ± 10 years, 1.79 ± 0.07 m, 77.5 ± 8.1 kg) consumed their habitual diet (∼30 g fiber/day) for 7 consecutive days followed by 4 days of a LOW (<10 g fiber/day) that was matched for energy and macronutrient content. Participants also matched their daily exercise load during LOW to that completed during habitual diet (p = .669, average 257 ± 141 arbitrary units). BM was significantly reduced in LOW versus habitual diet after 4 days (Δ = 0.40 ± 0.77 kg or 0.49% ± 0.91%, p < .05, effect size [ES] [95% confidence interval] = -0.53 [-1.17, 0.12]) and on the morning of Day 5 (Δ = 0.58 ± 0.83 kg or 0.74% ± 0.99%, p < .01, ES = -0.69 [-1.34, -0.03]). LOW resulted in moderately higher hunger (Δ = 5 ± 9 mm, p = .015, ES = 0.55 [-0.09, 1.20]), a decline in stool frequency from 2 ± 0 to 1 ± 0 bowel movements per day (p = .012, ES = 0.64 [-0.02, 1.29]) and stool softness decrease (p = .005). Nonetheless, participants reported the diet to be tolerable (n = 18/19) and were willing to repeat it (n = 16/19). Data demonstrate for the first time that consumption of a short-term LOW induces reductions in BM.

Nutrition for female athletes: What we know, what we don't know, and why.

Men are often considered as the default sex for studies in sports nutrition. Indeed, most of the seminal work to date in sports nutrition has been exclusively conducted on male participants. The 2021 Olympic Games had 49% female participation, signalling [almost] parity between sportsmen and sportswomen at the most elite sporting level for the first time. The volume of sports nutrition research using women as participants has, however, not kept pace with this rise in participation and professionalism. Therefore, to highlight what we currently know and don't know about sports nutrition for female athletes we invited well-known and emerging researchers to contribute to this special edition on Nutrition for Female Athletes. Contributions cover three main themes: dietary and hydration requirements; low energy availability and making weight; and dietary supplements and gut health. In addition, this special addition explores why our understanding on this topic is limited and how we can further progress and promote this research area.

Low energy availability in female athletes: From the lab to the field.

Decades of laboratory research have shown impairments to several body systems after only 4-5 days of strictly controlled consistent low energy availability (LEA); where energy availability (EA) = Energy Intake (EI) - Exercise Energy Expenditure (EEE)/Fat-Free Mass. Meanwhile, cross-sectional reports exist on the interrelatedness of LEA, menstrual dysfunction and impaired bone health in females (the Female Athlete Triad). These findings have demonstrated that LEA is the key underpinning factor behind a broader set of health and performance outcomes, recently termed as Relative Energy Deficiency in Sport (RED-S). There is utmost importance of early screening and diagnosis of RED-S to avoid the development of severe negative health and performance outcomes. However, a significant gap exists between short-term laboratory studies and cross-sectional reports, or clinically field-based situations, of long-term/chronic LEA and no definitive, validated diagnostic tests for RED-S exist. This review aims to highlight methodological challenges related to the assessment of the components of EA equation in the field (e.g. challenges with EI and EEE measures). Due to the uncertainty of these parameters, we propose the use of more chronic "objective" markers of LEA (i.e. blood markers). However, we note that direct extrapolations of laboratory-based outcomes into the field are likely to be problematic due to potentially poor ecological validity and the extreme variability in most athlete's daily EI and EEE. Therefore, we provide a critical appraisal of the scientific literature, highlighting research gaps, and a potential set of leading objective RED-S markers while working in the field. HighlightsDirect application of short-term laboratory-based findings in the field is problematic.Calculation of energy availability (EA) in the field is methodologically challenging and prone to errors.The use of several biomarkers may allow the detection of early exposure to low EA in the female athlete.

The Psychological and Physiological Consequences of Low Energy Availability in a Male Combat Sport Athlete.

PURPOSE: This study aimed to evaluate the effects of low energy availability (EA) on health and performance indices associated with the Male Athlete Triad and Relative Energy Deficiency in Sport (RED-S) models. METHODS: Over an 8-wk period, a male combat sport athlete adhered to a phased body mass (BM) loss plan consisting of 7-wk energy intake (EI) equating to resting metabolic rate (RMR) (1700 kcal·d-1) (phase 1), 5 d of reduced EI (1200-300 kcal·d-1) before weigh-in (phase 2), and 1 wk of ad libitum EI postcompetition (phase 3). EA fluctuated day by day because of variations in exercise energy expenditure. Regular assessments of body composition, RMR, cardiac function, cardiorespiratory capacity, strength and power, psychological state and blood clinical chemistry for endocrine, bone turnover, hydration, electrolyte, renal, liver, and lipid profiles were performed. RESULTS: BM was reduced over the 8-wk period by 13.5% (72.5 to 62.7 kg). No consequences of Male Athlete Triad or RED-S were evident during phase 1, where mean daily EA equated to 20 kcal·kg·fat free mass (FFM)-1·d-1 (range, 7 to 31 kcal·kg FFM-1·d-1) and BM and fat mass (FM) losses were 6.5 and 4.4 kg, respectively. However, consequences did present in phase 2 when mean daily EA was consistently <10 kcal·kg FFM-1·d-1, as evidenced by alterations to endocrine hormones (e.g., testosterone <5 nmol.L-1) and reduced RMR (-257 kcal·d-1). CONCLUSION: Data demonstrate that 7 wk of daily fluctuations in EA equating to a mean value of 20 kcal·kg FFM-1·d-1 permits reductions of BM and FM without perturbations to physiological systems associated with the Male Athlete Triad and RED-S. By contrast, a subsequent period of five consecutive days of EA <10 kcal·kg FFM-1·d-1 induced consequences of Male Athlete Triad and RED-S.