low energy availability – Dr Nicky Keay

The state of play on relative energy deficiency in sport (REDs): Psychological aspects

17 March 2024

Abstract

This article explores the current state of play regarding relative energy deficiency in sport (REDs), highlighting the recent updates from the International Olympic Committee (IOC) consensus statement September 2023. Psychological factors and mental health are recognised as having a reciprocal relationship in both the aetiology and outcome of chronic low energy availability leading to REDs. This has important implications in terms of prevention and management of individuals experiencing REDs. Unintentional or intentional unbalanced behaviours around exercise and nutrition leads to a situation of low energy availability. Low energy availability is not synonymous with REDs. Rather cumulative, sustained low energy availability, particularly low carbohydrate availability, leads to the clinical syndrome of REDs comprising a constellation of adverse consequences on all aspects of health and performance. This situation can potentially arise in both biological sexes, all ages and level of exerciser. This is of particular concern for the young aspiring athlete or dancer, where behaviours are being established and in terms of long-term consequences on mental and physical health. The mechanism of sustained low energy availability leading to these negative health outcomes is through the adaptive down regulation of the endocrine networks. Therefore, raising awareness of the risk of REDs and implementing effective prevention and identification strategies is a high priority.

Introduction

Relative energy deficiency in sport (REDs) was first described in the International Olympic Committee (IOC) consensus statement published in the British Journal of Sports and Exercise Medicine (BJSM) 2014 (Mountjoy, 2014). Since then, there have been updates published in 2018 (Mountjoy, 2018) and most recently in September 2023 (Mountjoy, 2023).

Seminal studies of female collegiate runners in 1980s found that those athletes with higher weekly training load, but same food intake as those with lower training load, experienced menstrual disruption, including secondary amenorrhoea and poor bone health (Drinkwater, 1984). This led to the description of the female athlete triad, which comprises a clinical spectrum of eating patterns, menstrual function and bone health. This ranges from optimal fuelling, menstrual function and bone health; to eating disorders, amenorrhoea and osteoporosis.

However, with further evidence emerging it became apparent that the impact of under fuelling is not confined to menstrual and bone health. Rather that the consequences of under fuelling are multisystem and can include male athletes. This led to the initial description of REDs in 2014 as a syndrome comprised of the potential adverse effects on many systems in the body with both physical and mental health implications. Crucially, unlike the female athlete trad, REDs also included the potential negative sequalae on athletic performance. Ultimately the goal for all athletes is to perform to their best, so REDs is not something of interest just in academic or clinical circles. REDs is highly relevant to both biological sexes and all levels and ages of exerciser.

What is Energy Availability?

The underlying aetiology of REDs is low energy availability. The life history theory describes how biological processes compete for energy resources (Shirley, 2022). Energy requirement for movement is prioritised from an evolutionary point of view in order to take evasion action from predators. The residual energy from food intake is described as energy availability. This is roughly equivalent to resting metabolic rate for the individual. Simply lying in bed all day, staying alive, is high energy demand for humans as homeotherms. The numerical value of energy availability is expressed in Kcals/Kg of fat free mass. The energy availability requirement for health will vary between individuals depending on sex, age and body composition. Although energy availability is a very useful concept, in practice is it not actually measured outside of the research setting. Rather objective surrogates indicating energy availability can be measured such as triiodothyronine (T3) which is used as a primary indicator of low energy availability as outlined in the update REDs clinical assessment tool described in further detail below (Stellingwerff, 2023 ).

An important highlight from the updated consensus statement on REDs is that it is specifically low carbohydrate availability that is most detrimental, especially for reproductive hormone networks. Comparing isocaloric intake, where there is a low proportion of energy from carbohydrate, this has the most marked negative consequence on both hormone health and performance. The mechanism of sustained low carbohydrate availability appears to involve the hormone leptin, an adipokine, secreted by adipose tissue. Low levels of leptin cause suppression of the reproductive axis via the hypothalamus-pituitary axis (Keay, 2022).

Aetiology of Low Energy Availability

Low energy availability is a situation where, once energy demand from movement has been met, the residual energy available is insufficient to support the functioning of other biological life process.

Low energy availability could arise unintentionally or intentionally (Keay, 2019). Unintentional low energy availability is where an exerciser does not appreciate the energy demands of exercise and other activities with an energy demand. For example, many athletes will not consider the energy required to “commute” to a training session on foot or bike. Unintentional low energy availability could be due to practical issues: for example, a long cycle ride over several hours will require the cyclist to take nutritional sources in the pockets of clothing and/or plan ahead suitable stops where it is possible to obtain nutrition. Similarly, going on a training camp, especially at altitude, will greatly increase energy demand from exercise and needs to factored in. Finances could also be a limiting factor.

On the other hand, intentional low energy availability is where an exerciser intentionally restricts nutrition intake in the belief that this might confer a performance advantage in terms of body weight, composition or shape. This is particularly associated with any exercise against gravity such as running, road cycling, climbing; weight category sports like martial arts and aesthetic forms of sport (diving, gymnastics) and dance.

For individuals with intentional low energy availability, psychology and mental health can have a reciprocal interaction (Pensgaard, 2023). Those exercisers with personality characteristics such as self-motivation, perfectionism can be very laudable traits in terms of dedication to exercise training to achieve success. However, when these characterises impact and support rigid behaviours around training and nutrition, this can become problematic. This is shown in Figure 1 “Psychological factors in REDs”. Those who are able to adapt to external pressures and have a flexible approach to training and nutrition are more likely to experience positive outcomes. Whereas those who have a more rigid approach, which might include disordered eating and or an eating disorder and/or exercise dependence are more likely to experience negative outcomes. This reinforces self-doubt and culminates in a vicious circle of perpetuating rigid behaviours and negative outcomes in terms of both physical and mental health.

Evidence for this interaction between psychological factors and risk of REDs was found in our study of dancers, referenced in the updated IOC consensus statement. A significant relationship was found between psychological factors such as anxiety around body shape/weight and missing training. These psychological factors in turn had significant associations between physical manifestations of low energy availability (low body weight) and physiological outcomes (menstrual irregularity) (Keay, 2020). Similarly, in more of our published research papers referenced in the IOC consensus statement focusing on male athletes, an significant association was found between cognitive nutritional restraint and negative physiological and performance outcomes (Jorov, 2021).

This reciprocal interaction between internal and external factors is a systems biology approach, highlighted in the recent updated IOC consensus statement. From a physiological point of view the brain is a high energy demand organ, requiring a good supply of glucose. So low carbohydrate availability will restrict this cerebral supply, which can impair cognitive function and ultimately good decision making. It is interesting to reflect that the neuroendocrine gatekeeper, the hypothalamus keeps a watching brief on internal and external factors, not distinguishing between the source of stressors when putting in motion an adaptive response (Keay, 2022).

Consequences of Low Energy Availabiity

Low energy availability is not synonymous with REDs. Indeed, short term low energy availability might initially bring some good performances. Low energy availability becomes problematic depending on the time scale, which in turn determines the degree of adaptive response, described in the clinical physiological model of REDs (Burke, 2023). The first system to adapt to low energy availability is bone: bone turnover moves in favour of resorption over formation. This is why bone stress responses, specifically bone stress fractures, can be an early warning sign of REDs and designated a primary indicator in the updated IOC consensus statement. There will follow sequential down regulation of metabolic rate mediated via the thyroid axis, followed by the reproductive axis. In women primary amenorrhoea or sustained functional hypothalamic amenorrhoea (FHA) of 6 months or more duration is a severe primary indicator of REDs. In men, low rage testosterone is a severe primary indicator. Ultimately body composition will be adversely affected, with the only endocrine system to be up regulated being that of the hypothalamic-pituitary-adrenal axis (Keay, 2019).

Health

Cumulative low energy availability causes the syndrome of REDs, which produces progressive adverse effects on all aspects of health: physical, mental and social, described in the REDs conceptual model. Poor sleep will compound these negative health effects (Keay, 2022).

Performance

Although there may be some initial good performances, chronic low energy availability will result in adverse performance consequences of REDs, described in the REDs performance conceptual model. In our referenced papers in the consensus statement, we found that in male athletes, short term low energy availability impacted performance (Jurov, 2022). In another of our referenced studies we showed that male cyclists in sustained low energy availability over 6 months, not only experienced bone loss commensurate to astronauts in space, but these cyclists also underperformed compared to their energy replete fellow cyclists (Keay, 2019). On a positive note, explaining to athletes and dancers that improving energy availability will improve their performance, can help in overcoming problematic behaviours.

Identification of those at risk

In view of the potential adverse health and performance effects of REDs, it is a priority to raise awareness of this risk to affect prevention. To this end the British Association of Sports and Exercise Medicine (BASEM) has a website health4performance.co.uk dedicated to providing reliable information on REDs for athletes, parents, coaches and health care professionals together with BASEM endorsed online courses. Targeting and identifying those at increased risk is very important. Young athletes and dancers can be most severely affected as down regulation of hormone function due to low energy availability can cause delay in growth and development. In particular, delayed puberty and menarche dampens the accrual of peak bone mass, with implications for bone health (Keay, 2000). Furthermore, there is evidence that these adverse effects on bone health might not be fully reversible (Keay, 1997)

From a psychological point of view, the young aspiring athlete and dancer is also at heightened risk. Explored and viewed by many dancers in “The Dark Side of Ballet Schools” Panorama (season 33, episode 28). Selection for specialised training will inevitably favour those who are self-motivated and dedicated. In a group of individuals sharing similar psychological traits this could act as a “breeding ground” for reinforcing these characteristics in ways that could lead to behaviours which are not conducive to positive outcomes. Rather reinforcing the negative interpretation of external and internal factors, leading to a vicious circle of reinforcing attitudes and behaviours leading to REDs, as described in Figure 1

Risk stratification

Early identification of those at risk of developing REDs is an important preventative strategy. Especially for young aspiring athletes and dancers where behaviours around eating and exercise are being developed and established. A step-by-step approach is provided in the updated version 2 of the Relative Energy Deficiency in sport Clinical Assessment Tool (REDsCat v2) to identify and risk stratify individuals (Stellingwerff, 2023 ). Initial, low cost, screening questionnaires can be helpful, particularly if tailored to a specific sport/activity or dance. For example: sports specific energy availability questionnaire (SEAQ) (Keay, 2018) and dance energy availability energy questionnaire (DEAQ) (Keay, 2020). This can be helpful in identifying those individuals where further investigation is clinically indicated. As REDs is a diagnosis of exclusion, targeted blood testing excludes medical conditions per se and provide objective quantification in the stratification of risk. Severe primary indicators of REDs are issues in the reproductive axis: long duration of amenorrhoea in females and low range testosterone in males.

From a combination of all these results the individual can be placed in an appropriate risk category. The updated REDs CAT v2 includes a finer grained approach with four categories from green, yellow, amber to red.

This assessment also provides the background on which to base the appropriate level of support. For all, management will be directed at restoring energy availability and include modification of training and nutritional intake. However, the details will vary according to the severity of REDs. Individuals with intentional REDs, especially when formally diagnosed with an eating disorder, will need most intensive input than a person with transient unintentional low energy availability.

Management

A nuanced approach is required for individual athletes, depending on their risk stratification and biopsychosocial factors. In all cases some degree of psychological support will be helpful. Involvement of the extended multidisciplinary team is ideal: medical doctor, dietician, coach and parent (where appropriate) with the athlete/dancer at the centre.

In order to restore energy availability this will require careful discussion around nutrition in terms of consistency of eating patterns and composition of food groups consumed. This starts with regular meals containing good portions of complex carbohydrate and protein. Studies show that inconsistent intake of carbohydrate (eg “backloading” eating to the evening) produces an unfavourable hormone profile. Fuelling around training is also a high priority for hormone health and driving positive adaptations to exercise. Pre training consumption of carbohydrate together with post training refuelling with both complex carbohydrate and protein within 20 minutes of stopping are important behaviours for favourable hormone response to exercise (Keay, 2022).

In terms of pharmacological intervention, NICE guidelines have been updated 2022 in recommending body identical hormone replacement therapy (HRT) over the combined oral contraceptive pill (COCP) for bone protection in those with evidence of bone poor health due to functional hypothalamic amenorrhoea (FHA) as a consequence of REDs (BASEM, 2023). Poor bone health is defined as age matched Z score < -1 of the lumbar spine (trabecular bone particularly sensitive to low oestradiol) and/or 2 or more stress fractures at a site of concern (trabecular rich bone). For male athletes/dancers external testosterone is not appropriate as this supresses internal hormone production. Furthermore, testosterone is on the world anti-doping authority (WADA) banned list and it is not possible to obtain a therapeutic use exemption (TUE) as REDs is a functional condition, not a medical condition.

Prevention

Prevention is always the ultimate goal. In order to achieve this aim, a cultural shift in sport and dance is required. Emphasis on the fact that health is a prerequisite for performance. Pursuing a lighter body weight or leaner body composition will not automatically lead to improved performance. Each individual will have a personal tipping point. As we are all different, there is no such thing as a generic “ideal” weight/shape/body composition.

In practical terms, prevention can be considered as primary, secondary and tertiary (Torstveit, 2023). Primary prevention consists of providing and disseminating reliable educational resources. Secondary prevention includes early identification of those at risk of developing REDs, together with prompt and correct diagnosis. For example, regardless of whether an athlete or dancer, amenorrhoea in a woman of reproductive age (apart from physiological amenorrhoea of pregnancy) is never “normal”; whether blood tests are in range, or not. The tertiary level of prevention encompasses evidence-based treatments. As mentioned above, NICE guidelines are now in line with Endocrine Society and IOC in advising temporising HRT for bone protection in FHA. Not the COCP which masks underlying hormone dysfunction and is not bone protective. Similarly, thyroxine is not advised where there is downregulation of this axis as a consequence of REDs. This is not the same as the medical condition of a primary underactive thyroid indicated by raised thyroid stimulating hormone (TSH) (Keay, 2022).

Conclusion

Ultimately, we all have a role to play in supporting exercisers, athletes and dancers in avoiding “the REDs card” (Mountjoy, 2023). This involves the extended multidisciplinary team, starting with the individual exerciser, family, friends and coaches. Then bringing in health care professionals from medicine, dietetics and physiotherapy.

Imbalances in behaviours around exercise and nutrition can have potential negative consequences on all aspects of health and performance. On a positive note, exercise, supported with appropriate nutrition, is an excellent way to achieve and maintain optimal physical, mental and social health and support performance. This is applicable for all ages and levels of exercisers from the recreational to the amateur and elite athlete.

References

Burke LM, Ackerman KE, Heikura IAet al. 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 British Journal of Sports Medicine 2023;57:1098-1108.

Drinkwater B, Nilson K, Chesnut C. Bone Mineral Content of Amenorrheic and Eumenorrheic Athletes N Engl J Med 1984; 311:277-281 DOI: 10.1056/NEJM198408023110501

Jurov I, Keay N, Hadžić V et al. Relationship between energy availability, energy conservation and cognitive restraint with performance measures in male endurance athletes. J Int Soc Sports Nutr 2021;18:24. doi:10.1186/s12970-021-00419-3

Jurov I, Keay N, Spudić D et al. Inducing low energy availability in trained endurance male athletes results in poorer explosive power. Eur J Appl Physiol 2022;122:503–13. doi:10.1007/s00421-021-04857-4

Keay N Hormones, Health and Human Potential: A guide to understanding your hormones to optimise your health and performance 2022 Sequoia books

Keay N, Overseas A, Francis G. Indicators and correlates of low energy availability in male and female dancers BMJ Open Sport & Exercise Medicine 2020;6:e000906. doi: 10.1136/bmjsem-2020-000906

Keay N, Francis G. Infographic. Energy availability: concept, control and consequences in relative energy deficiency in sport (RED-S) British Journal of Sports Medicine 2019;53:1310-1311.

Keay N, Rankin A. Infographic. Relative energy deficiency in sport: an infographic guide

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Keay N, Francis G, Hind K. Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists BMJ Open Sport & Exercise Medicine 2018;4:e000424. doi: 10.1136/bmjsem-2018-000424

Keay N, Francis G, Entwistleet al. Clinical evaluation of education relating to nutrition and skeletal loading in competitive male road cyclists at risk of relative energy deficiency in sports (RED-S): 6-month randomised controlled trial BMJ Open Sport & Exercise Medicine 2019;5:e000523. doi: 10.1136/bmjsem-2019-000523

Keay N. The modifiable factors affecting bone mineral accumulation in girls: the paradoxical effect of exercise on bone. Nutrition Bulletin 2000, 25: 219-222. https://doi.org/10.1046/j.1467-3010.2000.00051.x

Keay N, Fogelman I, Blake G. Bone mineral density in professional female dancers.

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Mountjoy M, Ackerman KE, Bailey Det al. 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) British Journal of Sports Medicine 2023;57:1073-1097.

Mountjoy M, Ackerman KE, Bailey Det al. Avoiding the ‘REDs Card’. We all have a role in the mitigation of REDs in athletes British Journal of Sports Medicine 2023;57:1063-1064.

Pensgaard AM, Sundgot-Borgen J, Edwards Cet al. Intersection of mental health issues and Relative Energy Deficiency in Sport (REDs): a narrative review by a subgroup of the IOC consensus on REDs British Journal of Sports Medicine 2023;57:1127-1135.

Stellingwerff T, Mountjoy M, McCluskey Wet al. 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 British Journal of Sports Medicine 2023;57:1109-1118.

International Olympic Committee relative energy deficiency in sport clinical assessment tool 2 (IOC REDs CAT2) British Journal of Sports Medicine 2023;57:1068-1072.

Shirley M, Longman D, Elliott-Sale K et al. A Life History Perspective on Athletes with Low Energy Availability. Sports Med 2022 52, 1223–1234. https://doi.org/10.1007/s40279-022-01643-w

Todd E, Elliot N, Keay N. Relative energy deficiency in sport (RED-S) British Journal of General Practice 2022; 72 (719): 295-297. DOI: https://doi.org/10.3399/bjgp22X719777

Torstveit M, Ackerman K, Constantini N et al. Primary, secondary and tertiary prevention of Relative Energy Deficiency in Sport (REDs): a narrative review by a subgroup of the IOC consensus on REDs Br J Sports Med 2023;57:1119–1126.

Low Energy Availability in Climbers

17 November 2018

Listen into a great discussion I had with Dr Nigel Callender an ex competitive climber and climbing coach about the “elephant in the room” in competitive climbing.

Discussion of Low Energy Availability and RED-S

As a gravitational sport, being a light-weight climber confers a performance advantage. However, being alert to low energy availability and the clinical consequences of RED-S on health and performance is important for climbers. With climbing being included the next Olympics, then hopefully this will raise awareness of being alert to athletes at risk of low energy availability and RED-S.

Insights from Dr Nigel Callender, sports scientist turned medical doctor (anaesthetics/critical care trainee) an active researcher, largely into the exercise physiology aspects of climbing and ex-competitor, having represented Ireland at international level and been British bouldering champion before shoulder injuries ended that. Sport climbing is included in the 2020 Tokyo summer games in its three competitive disciplines; bouldering, lead climbing and speed climbing. Each sub-discipline has a slightly different athlete profile and physiological demands, but all are obviously under the heading of gravity dependent sports. Current participation figures put yearly indoor climbing participation at around the one million mark in the UK and it is said to be one of the fastest growing sports worldwide. The sport is being recognised as a great way to improve overall health and fitness, with recent papers citing it as a useful rehab activity for many physical and mental health conditions and also as a health promotion tool.

Although climbing has been a formal competitive sport in some sense since the late 80’s, it still lacks much in the way of formal training and medical guidelines. Being a gravity dependent sport, strength to weight ratio is important, however Dr Callender and his colleagues are seeing a high incidence of restrictive eating patterns at all levels of the sport and a lack of awareness around the performance impairments and health risks associated with a significant or prolonged negative energy balance in some athletes.

The Outdoor Athlete Podcast is a bit of a winter project that came about to establish a gold-standard resource, driven by credible experts in their relevant fields, as an attempt to provide high-quality and evidence-based information amongst the confusing advice that is now the internet. It’s free and always will be and it was inspired by the BJSM Podcasts though broadly aiming at ‘Outdoor Athletes’ e.g. Climbers, Fell/Trail runners, Mountain bikers and anyone happy to listen.

For more information on climbing in the UK, including competition climbing see http://www.thebmc.co.uk

Raising Awareness of RED-S in Male and Female Athletes and Dancers

11 October 2018

Health4Performance is a recently developed BASEM open access educational resource

This is a world premier: a resource developed for and by athletes/dancers, coaches/teachers, parents/friends and healthcare professionals to raise awareness of Relative Energy Deficiency in Sport (RED-S)

What?

Optimal health is required to attain full athletic potential. Low energy availability (LEA) can compromise health and therefore impair athletic performance as described in the RED-S clinical model.

Dietary energy intake needs to be sufficient to cover the energy demands of both exercise training and fundamental physiological function required to maintain health. Once the energy demands for training have been covered, the energy left for baseline “housekeeping” physiological function is referred to as energy availability (EA). EA is expressed relative to fat free mass (FFM) in KCal/Kg FFM. The exact value of EA to maintain health will vary between genders and individuals, roughly equivalent to resting metabolic rate of the individual athlete/dancer. LEA for an athlete or dancer will result in the body going into “energy saving mode” which has knock on effects for many interrelated body systems, including readjustment to lower the resting metabolic rate in the longer term. So although loss in body weight may be an initial sign, body weight can be steady in chronic LEA due to physiological energy conservation adaptations. Homeostasis through internal biological feedback loops in action.

The most obvious clinical sign of this state of LEA in women is cessation of menstruation (amenorrhea). LEA as a cause of amenorrhoea is an example of functional hypothalamic amenorrhoea (FHA). In other words, amenorrhoea arising as a result of an imbalance in training load and nutrition, rather than an underlying medical condition per se, which should be excluded before arriving at a diagnosis of FHA. All women of reproductive age, however much exercise is being undertaken, should have regular menstrual cycles, which is indicative of healthy hormones. This explains why LEA was first described as the underlying aetiology of the female athlete triad, as women in LEA display an obvious clinical sign of menstrual disruption. The female athlete triad is a clinical spectrum describing varying degrees of menstrual dysfunction, disordered nutrition and bone mineral density. However it became apparent that the clinical outcomes of LEA are not limited to females, nor female reproductive function and bone health in female exercisers. Hence the evolution of the clinical model of RED-S to describe the consequences of LEA on a broader range of body systems and including male athletes.

A situation of LEA in athletes and dancers can arise unintentionally or intentionally. In the diagram below the central column shows that an athlete where energy intake is sufficient to cover the demands from training and to cover basic physiological function. However in the column on the left, although training load has remained constant, nutritional intake has been reduced. This reduction of energy intake could be an intentional strategy to reduce body weight or change body composition in weight sensitive sports and dance. On the other hand in the column on the right, training load and hence energy demand to cover this has increased, but has not been matched by an increase in dietary intake. In both these situations, whether unintentional or intentional, the net results is LEA, insufficient to maintain health. This situation of LEA will also ultimately impact on athletic performance as optimal health is necessary to realise full athletic potential.

Although LEA is the underlying aetiology of RED-S, there are many methodological and financial issues measuring LEA accurately in “free living athletes“. In any case, the physiological response varies between individuals and depends on the magnitude, duration and timing of LEA. Therefore it is more informative to measure the functional responses of an individual to LEA, rather than the value calculated for EA. As such, Endocrine markers provide objective and quantifiable measures of physiological responses to EA. These markers also reflect the temporal dimension of LEA; whether acute or chronic. In short, as hormones exert network effects, Endocrine markers reflect the response of multiple systems in an individual to LEA. So by measuring these key markers, alongside taking a sport specific medical history, provides the information to build a detailed picture of EA for the individual, with dimensions of time and magnitude of LEA. This information empowers the athlete/dancer to modify the 3 key factors under their control of training load, nutrition and recovery to optimise their health and athletic performance.

Why?

Who is at risk of developing RED-S? Any athlete involved in sports or dance where being light weight confers a performance or aesthetic advantage. This is not restricted to elite athletes and dancers. Indeed the aspiring amateur or exerciser could be more at risk, without the benefit of a support team present at professional level. Young athletes are at particular risk during an already high energy demand state of growth and development. Therefore early identification of athletes and dancers at risk of LEA is key to prevention of development of the health and performance consequences outlined in the RED-S clinical model. Although there is a questionnaire available for screening for female athletes at risk of LEA, more research is emerging for effective and practical methods which are sport specific and include male athletes.

How?

Early medical input is important as RED-S is diagnosis of exclusion. In other words medical conditions per se need to be ruled out before arriving at a diagnosis of RED-S. Prompt medical review is often dependent on other healthcare professionals, fellow athletes/dancers, coaches/teachers and parents/friends all being aware and therefore alert to RED-S. With this in mind, the Health4Performance website has areas for all of those potentially involved, with tailored comments on What to look out for? What to do? Ultimately a team approach and collaboration between all these groups is important. Not only in identification of those at risk of LEA, but in an integrated support network for the athlete/dancer to return to optimal health and performance.

References

Heath4Performance BASEM Educational Resource

Video introduction to Health4Performance website

2018 UPDATE: Relative Energy Deficiency in Sport (RED-S) BJSM 2018

What is Dance Medicine? BJSM 2018

Identification and management of RED-S Podcast 2018

Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists Keay, Francis, Hind. BJM Open Sport and Exercise Medicine 2018

How to Identify Male Cyclists at Risk of RED-S? 2018

Pitfalls of Conducting and Interpreting Estimates of Energy Availability in Free-Living Athletes IJSNM 2018

Low Energy Availability Is Difficult to Assess but Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes IJSNM 2017

The LEAF questionnaire: a screening tool for the identification of female athletes at risk for the female athlete triad BJSM 2013

IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update BJSM 2018

How to Identify Male Cyclists at Risk of RED-S?

5 October 2018

Relative energy deficiency in sport (RED-S) is a clinical model that describes the potential adverse health and performance consequences of low energy availability (LEA) in male and female athletes. Identification of athletes at risk of LEA can potentially prevent these adverse clinical outcomes.

Athletes at risk of RED-S are those involved in sports where low body weight confers a performance or aesthetic advantage. In the case of competitive road cycling, being light weight results in favourable power to weight ratio to overcome gravity when cycling uphill. How can male cyclists at risk of LEA be effectively identified in a practical manner?

Energy availability (EA) is defined as the residual energy available from dietary intake, once energy expenditure from exercise training has been subtracted. This available energy is expressed as KCal/Kg fat free mass (FFM). A value of 45 KCal/Kg FFM is roughly equivalent to basal metabolic rate, in other words the energy required to sustain health. In order to quantify EA, accurate measurements of energy intake and expenditure, and FFM assessed from dual X ray absorptiometry (DXA), need to be undertaken. However this is not practical or feasible to undertake all these measurements outside the research setting. Furthermore, methodology for assessing energy intake and expenditure is laborious and fraught with inaccuracies and subjectivity in the case of diet diaries for “free living athletes“. Even if a value is calculated for EA, this is only valid for the time of measurement and does not give any insights into the temporal aspect of EA. Furthermore, an absolute EA threshold has not been established, below which clinical symptoms or performance effects of RED-S occur.

Self reported questionnaires have been shown to be surrogates of low EA in female athletes. However there are no such sport specific questionnaires, or any questionnaires for male athletes. Endocrine and metabolic markers have been proposed as quantitative surrogate measures of EA and shown to be linked to the RED-S clinical outcome of stress fractures in runners. In female athletes the clinical sign of regular menstruation demonstrates a functioning H-P ovarian axis, not suppressed by LEA. What about male athletes? Although hypothalamic suppression of the reproductive axis due to LEA can result in low testosterone, high training loads, in presence of adequate EA, can lead to the same negative effect on testosterone concentration.

Male cyclists present a further level of complexity in assessing EA status. In contrast to runners, stress fracture will not be an early clinical warning sign of impaired bone health resulting from low EA. Furthermore cyclists are already at risk of poor bone health due to the non weight bearing nature of the sport. Nevertheless, traumatic fracture from bike falls is the main type of injury in cycling, with vertebral fracture requiring the longest time off the bike. Chris Boardman, a serial Olympic medal winner in cycling, retired in his early 30s with osteoporosis. In other words, in road cycling, the combined effect of the lack of osteogenic stimulus and LEA can produce clinically significant adverse effects on bone health.

What practical clinical tools are most effective at identifying competitive male cyclists at risk of the health and performance consequences of LEA outlined in the RED-S model? This was the question our recent study addressed. The lumbar spine is a skeletal site known to be most impacted by nutrition and endocrine factors and DXA is recognised as the “gold standard” of quantifying age matched Z score for bone mineral density (BMD) in the risk stratification of RED-S. What is the clinical measure indicative of this established and clinically significant sign of RED-S on lumbar spine BMD? Would it be testosterone concentration, as suggested in the study of runners? Another blood marker? Cycle training load? Off bike exercise, as suggested in some previous studies? Clinical assessment by interview?

Using a decision tree approach, the factor most indicative of impaired age matched (Z score) lumbar spine BMD was sport specific clinical assessment of EA. This assessment took the form of a newly developed sports specific energy availability questionnaire and interview (SEAQ-I). Reinforcing the concept that the most important skill in clinical medical practice is taking a detailed history. Questionnaire alone can lead to athletes giving “correct” answers on nutrition and training load. Clinical interview gave details on the temporal aspects of EA in the context of cycle training schedule: whether riders where experiencing acute intermittent LEA, as with multiple weekly fasted rides, or chronic sustained LEA with prolonged periods of suppressed body weight. Additionally the SEAQ-I provided insights on attitudes to training and nutrition practices.

Cyclists identified as having LEA from SEAQ-I, had significantly lower lumbar spine BMD than those riders assessed as having adequate EA. Furthermore, the lowest lumbar spine BMD was found amongst LEA cyclists who had not practised any load bearing sport prior to focusing on cycling. This finding is of particular concern, as if cycling from adolescence is not integrated with weight bearing exercise and adequate nutrition when peak bone mass (PBM) is being accumulated, then this risks impaired bone health moving into adulthood.

Further extension of the decision tree analysis demonstrated that in those cyclists with adequate EA assessed from SEAQ-I, vitamin D concentration was the factor indicative of lumbar spine BMD. Vitamin D is emerging as an important consideration for athletes, for bone health, muscle strength and immune function. Furthermore synergistic interactions with other steroid hormones, such as testosterone could be significant.

What about the effects of EA on cycling performance? For athletes, athletic performance is the top priority. In competitive road cycling the “gold standard” performance measure is functional threshold power (FTP) Watts/Kg, produced over 60 minutes. In the current study, 60 minute FTP Watts/Kg had a significant relationship to training load. However cyclists in chronic LEA were under performing, in other words not able to produce the power anticipated for a given training load. These chronic LEA cyclists also had significantly lower testosterone concentration. Periodised carbohydrate intake for low intensity sessions is a strategy for increasing training stimulus. However if this acute intermittent LEA is superimposed on a background of chronic LEA, then this can be counter productive in producing beneficial training adaptations. Increasing training load improves performance, but this training is only effective if fuelling is tailored accordingly.

Male athletes can be at risk of developing the health and performance consequences of LEA as described in the RED-S clinical model. The recent study of competitive male road cyclists shows that a sport specific questionnaire, combined with clinical interview (SEAQ-I) is an effective and practical method of identifying athletes at risk of LEA. The temporal dimension of LEA was correlated to quantifiable health and performance consequences of RED-S.