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

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.

Sam

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.

References 

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, BMJ Open in Sport and Exercise Medicine 2018

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

Fuelling for Cycling Performance Science4Performance

Pitfalls of Conducting and Interpreting Estimates of Energy Availability in Free-Living Athletes International Journal of Sport Nutrition and Exercise Metabolism 2018

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

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

Low Energy Availability Is Difficult to Assess but Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes International Journal of Sport Nutrition and Exercise Metabolism 2018

Treating exercise-associated low testosterone and its related symptoms The Physician and Sports Medicine 2018

Male Cyclists: bones, body composition, nutrition, performance Keay, BJSM 2018

Cyclists: Make No Bones About It Keay, BJSM 2018

Male Athletes: the Bare Bones of Cyclists

Cyclists: How to Support Bone Health?

Synergistic interactions of steroid hormones Keay BJSM 2018

Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis Sports Medicine 2018

 

Healthy Hormones

Is your training in tune with your hormones and nutrition to optimise your athletic performance?

Hormones are internal chemical messengers regulating all aspects of your health and athletic performance. Discussed at recent BASEM conference “Health Hormones and Human Performance”

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Bone health can be at risk if hormone status not optimal

How? To enable your hormones to do the best job they can for your health and sport performance, you need to find a balance between what, how much and when you train, eat and sleep. In the diagram below, this represents staying on the healthy green plateau. Too much, or too little of any of these choices can lead to imbalances and tipping off the green plateau into the red, less healthy peripheries.

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Integrated periodisation of training, nutrition and recovery for optimal health and performance (Keay, BJSM 2017)

What? Imbalances between training load, nutrition and recovery can cause problems in the Endocrine system: the whole network of hormone interactions throughout your body. The bottom line is that if insufficient energy is provided through nutrition to cover both your training demands and the “housekeeping” activities within the body to keep you alive, then your body goes into energy saving mode. This situation is called relative energy deficiency in sports (RED-S) and has the potential to adversely impact one or more of the important systems in your body vital for optimal health and performance.

RED-S has evolved from the female athlete triad described in 1980s by Barbara Drinkwater in NEJM, where although female runners were consuming same dietary intake, those with higher training load were more likely to have menstrual dysfunction and low bone mineral density. Since this original description it has become obvious that the reproductive axis is just one of several hormone networks to be impacted by low energy availability and that RED-S also impacts the other half of the population: men.

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Potential Multisystem effects of RED-S (IOC statement BJSM 2014)

Why? Suboptimal levels of energy availability to support health and performance can arise unintentionally, for example with increased training loads and/or times of growth and development in young athletes. Intentionally restrictive eating patterns can also be the cause of RED-S, particularly in sports/dance where low body weight confers a performance or aesthetic advantage. It is an indisputable fact that in order cycle up a mountain you need to overcome gravity and produce high watts/kg. Equally it is pretty impossible to do pointe work, let alone 32 fouttées en tournant en pointe unless you are a lightweight dancer. However if this at the expense of disrupting your hormones, then the advantage of being low body weight will be lost.

How to know? How to know if you, a teammate or a fellow athlete is at risk of RED-S? If you are a female athlete then your hormones are in balance if you are having regular periods (this does not include withdrawal bleeds as result of being on the oral contraceptive pill). Any woman of reproductive age from 16 years to the menopause should have regular periods (unless pregnant). Regular menstruation acts as the barometer of healthy hormones in women. If this is not the case, whether you are an athlete or not, you need to get this checked out medically to exclude underlying medical conditions. Having excluded these, then you need to review the integrated periodisation of training, nutrition and recovery. In male athletes there is not such an obvious sign that your hormones are at healthy levels. However recurrent injury/illness/fatigue can be warning signs. The diagram below shows all the potential adverse effects of RED-S on performance. Be aware that you do not have to have all, or indeed be aware of any of these effects if you develop RED-S.

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Potential Performance effects of RED-S (IOC statement BJSM 2014)

So What? If you are an athlete/dancer, you may be thinking that none of this applies to you. You are feeling and performing fine. Maybe you have not yet experienced any of the detrimental effects of RED-S. However, you will never know how good an athlete you could be and whether you truly are performing to your full potential unless you put yourself in the best position in terms of your hormones to achieve this goal.

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Suboptimal performance as result of RED-S (Keay, BJSM 2017)

Key Points

• Insufficient nutrition intake (quantity and quality), whether intentional or not, results in RED-S and multiple hormonal disruptions

• RED-S has detrimental health and athletic performance consequences in both the short and the long term

• Some consequences of RED-S are irreversible for example poor bone health, unless intervention is swift

Check points

• Are you suffering with frequent injuries/fatigue/illness over last 3 months or more?

• Female athletes: if 16 years or older have your periods not started? Have you missed more than 3 consecutive periods?

If yes to any of above, seek medical advice from someone with experience Sports Endocrinology. Now! The longer you leave the situation the harder it will be to rectify. Initially underlying Endocrine conditions per se have to be ruled out. RED-S is a functional dysfunction of the Endocrine system, so a diagnosis of exclusion. Having established RED-S as the diagnosis, monitoring Endocrine markers can be very helpful as these are examples of objective metrics in monitoring energy availability and therefore response to optimising integrated periodisation of nutrition, training and recovery.

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Integrated periodisation of key training factors support healthy hormones to drive improvements in performance

What to do? Don’t ignore! Although you may think you are fine, if your hormones are not working for you, then you will never reach your full potential as an athlete/dancer. For female athletes having regular periods means your hormones are in healthy ranges and this is normal. Not starting and/or missing periods is not healthy, for any woman.

For both male and female athletes, if you are experiencing recurrent injury, fatigue or illness, you need to get this checked out. There may be a simple explanation such as viral infection, low vitamin D or iron. However it may be that the underlying reason is due to hormone issues.

If you are an athlete, coach, teacher or parent and concerned that you/an athlete in your care has not got the balance right to optimise health and athletic performance, then a 3 way discussion will help and support the decision to seek medical advice as appropriate.

References

Lifestyle Choices for optimising health: exercise, nutrition, sleep Keay, BJSM 2017

Optimal health: including female athletes! Part 1 BJSM 2017

Optimal health: including male athletes! Part 2 BJSM 2017

Optimal Health: Especially Young Athletes! Part 3 BASEM 2017

Optimal Health: For All Athletes! Part 4 BASEM 2017

Low Energy Availability is Difficult to Assess But Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes Sport Nutrition and exercise Metabolism 2017

Cumulative Endocrine Dysfunction in Relative Energy Deficiency in Sport (RED-S) BJSM 2018

Presentation at BASEM conference “Health, Hormones and Human Performance”

 

Health, Hormones and Human Performance Part 1

How hormones determine health and athletic performance

Endocrine and Metabolic aspects of Sports and Exercise Medicine are crucial determinants of health and human performance, from reluctant exerciser through to elite athlete and professional dancer. This is what I set out to demonstrate as the chair of the recent British Association of Sport and Medicine conference, with insightful presentations from my colleagues whom I had invited to share their research and practical applications of their work. The audience comprised of doctors with interest in sport and exercise medicine, representatives from the dance world, research scientists, nutritionists, physiotherapists, coaches and trainers. In short, all were members of multi-disciplinary teams supporting aspiring athletes. The importance of the conference was reflected in CDP awards from FSEM, BASES, Royal College of Physicians (RCP), REP-S and endorsement for international education from BJSM and National Institute of Dance Medicine and Science (NIDMS).

Exercise is a crucial lifestyle factor in determining health and disease. Yet we see an increasing polarisation in the amount of exercise taken across the general population. At one end of the spectrum, the increasing training loads of elite athletes and professional dancers push the levels of human performance to greater heights. On the other side of the spectrum, rising levels of inactivity, in large swathes of the population, increase the risk of poor health and developing disease states. Which fundamental biological processes and systems link these groups with apparently dichotomous levels of exercise? What determines the outcome of the underlying Endocrine and metabolic network interactions? How can an understanding of these factors help prevent sports injuries and lead to more effective rehabilitation? How can we employ Endocrine markers to predict and provide guidance towards beneficial outcomes for health and human performance?

If you weren’t able to come and participate in the discussion, these are some topics presented. My opening presentation (see video below) set the scene, outlining why having an optimally functioning Endocrine system is fundamental to health and performance. Conversely, functional disruption of Endocrine networks occurs with non integrated periodisation of the three key lifestyle factors of exercise/training, nutrition and recovery/sleep, which can lead to adverse effects on health and athletic performance.

In the case of an imbalance in training load and nutrition, this can manifest as the female athlete triad, which has now evolved into relative energy deficiency in sports (RED-S) in recognition of the fact that Endocrine feedback loops are disrupted across many hormonal axes, not just the reproductive axis. And, significantly, acknowledging the fact that males athletes can also be impacted by insufficient energy availability to meet both training and “housekeeping” energy requirements. Why and how RED-S can affect male athletes, in particular male competitive road cyclists, was discussed, highlighting the need for further research to investigate practical and effective strategies to optimise health and therefore ultimately performance in competition.

A degree of overlap and interplay exists between RED-S (imbalance in nutrition and training load), non functional over-reaching and over-training syndrome (imbalances in training load and recovery). Indeed research evidence was presented suggesting that RED-S increases the risk of developing over-training syndrome. In these situations of functional disruption of the Endocrine networks, underlying Endocrine conditions per se should be excluded. Case studies demonstrated this principle in the diagnosis of RED-S. This is particularly important in the investigation of amenorrhoea. All women of reproductive age, whether athletes or not, should have regular menstruation (apart from when pregnant!), as a barometer of healthy hormones. Indeed, since hormones are essential to drive positive adaptations to exercise, healthy hormones are key in attaining full athletic potential in any athlete/dancer, whether male or female. Evidence was presented from research studies for the role of validated Endocrine markers and clinical menstrual status in females as objective and quantifiable measures of energy availability and hence injury risk in both male and female athletes.

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Triumvirate of external factors impacting Endocrine system and hence performance

Alongside training metrics, if female athletes recorded menstrual pattern (as Gwen Jorgensen recently showed on her Training Peaks) and all athletes kept a biological passport of selected Endocrine markers; this could potentially identify at an early stage any imbalances in the triumvirate of training load, nutrition and recovery. Pre-empting development of RED-S or over-training syndrome, supports the maintenance of healthy hormones and hence optimal human performance.

Look out for presentations from speakers which will be uploaded on BASEM website shortly.

References

Video of presentation on the Endocrine and Metabolic Aspects of Sports and Exercise Medicine BASEM conference “Health, Hormones and Human Performance”

Study of hormones, body composition, bone mineral density and performance in competitive male road cyclists Investigation of effective and practical nutrition and off bike exercise interventions

Sports Endocrinology – what does it have to do with performance? Keay BJSM 2017

 

 

 

Cyclists: How to Support Bone Health?

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Supporting Bone Health

The wonderfully named “hip hop” study was conducted to investigate whether hopping would improve the strength of the hip bone in older males. You may be wondering how this is relevant to male cyclists in their twenties. Yet, in a recent pilot study, some male cyclists were found to have areas of the skeleton that were below average bone mineral mineral (BMD) for an 85 year old man. This finding of low BMD in cyclists was confirmed in a recent BBC programme where Dr Karen Hind at Leeds Beckett University presented the differences in BMD across sports. Keen-eyed cyclists amongst you will have recognised Ed Clancy from JLT Condor representing cyclists, though these findings will be relevant to all levels of competitive cyclists.

So maybe research with the same aims as the “hip hop” study is exactly what needs to be conducted amongst male cyclists to investigate practical and effective ways of supporting bone health and ultimately preventing injury and optimising performance. This is aim of forthcoming research in collaboration with Dr Hind.

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Microscopic structure of bone

In common with other sports, cycling is an excellent form of exercise, driving positive adaptations throughout the body, such as improved cardiovascular fitness, body composition, muscular strength and endurance together with beneficial psychological effects. However, unlike many other forms of exercise, cycling does not encourage beneficial adaptations to the full skeletal system. This is due to a lack of mechanical osteogenic (bone building) stimuli provided in cycling, particularly at the lumbar spine. In competitive road cycling, low body mass confers a performance advantage, so restrictive or inconsistent nutrition can lead to relative energy deficiency in sport (RED-S). The consequent Endocrine system dysfunction can compound the negative effects on bone health of a non-load-bearing sport.

In a study of masters cyclists, decreases in BMD at all sites were more marked than in sedentary individuals. Some cyclists went from being osteopenic to osteoporotic; a rare case where exercise has a negative impact on a system in the body. Does this matter? Like all athletes, cyclists are more concerned with current athletic performance than warnings about future issues, such as osteoporosis and fracture. Yet, out of athletes across all sports, cyclists should perhaps be the most concerned. In the case of runners, suboptimal bone heath and associated RED-S may well present as a stress fracture. In the case of cyclists by the nature of non-load bearing exercise, they can push for longer with suboptimal bone and nutritional status. The full extent of any bone health issues may only come to light as result of a bike crash. Looking at the time off from injury in elite cyclists, the majority are due to fracture, with vertebral fractures often requiring long duration of recovery compared to other sites.

Maybe maintenance of BMD for adult cyclists would be realistic goal. How can this be achieved?

Multidirectional, dynamic loading patterns have been shown to produce the most positive skeletal responses. This is seen in the different site specific effects of sports, where changes of direction or plane of movement provide maximal mechanical osteogenic stimulus. Jumping and hopping have been shown to be good for bone health in premenopausal women, where brief high impact exercises were found to be beneficial for the bone mineral density (BMD) of the femoral neck of the hip.

What about targeting the lumbar spine, which is the site most at risk in cyclists? In young children, a few mechanical loading cycles of two-footed jumping from a small step improved BMD at lumbar spine compared with those that did not perform this jumping exercise. However bone is at its most responsive in childhood and skeletal loading has a more long term effect on both microarchitecture and BMD than when performed as an adult. Nevertheless, even in adulthood bone is still a dynamic tissue, able to adapt to loading stresses. Resistance training seems to be the most effective way of providing mechanical osteogenic stimulus to the lumbar spine with an additional indirect osteogenic effect of muscle pulling on bone. For example rowers have site-specific increases in BMD at the lumbar spine. In a recent study, resistance training was found to improve BMD in male distance runners with similar levels of testosterone and bone markers. This concurs with recent pilot study of cyclists, where those performing current resistance training or with recent history of participating in other sports, such as rugby or rowing, fared better in terms of BMD. In other words, the improvement in BMD mediated via mechanical rather than Endocrine effects.

Nevertheless, any form of skeletal-loading exercise will not produce the expected beneficial osteogenic effect, if performed in suboptimal nutritional status. Sufficient quantity and quality of nutrition are required to prevent RED-S. Specific nutritional factors, such as vitamin D, calcium and polyphenols, are recognised to be important in bone health. Boron is also described as decreasing bone resorption by stabilising and extending the half-life of vitamin D and improving sex steroid availability. Whilst high intake of caffeine, which can accumulate if athletes take on board caffeine gels, has a negative impact on BMD. Optimal nutritional status will in turn support the Endocrine system to mediate advantageous adaptations to exercise exercise, including bone health.

How can cyclists optimise bone health and performance on the bike with consistent and targeted skeletal-loading exercise and nutritional strategies? Watch this space! A study is planned to investigate practical and effective strategies to achieve this. No on bike hip hop dance required.

In meantime there will be more discussion on “Health, Hormones and Human Performance” at the BASEM conference 22 March. All welcome, including athletes and coaches, alongside healthcare professional working with athletes.

References

Male Athletes: the Bare Bones of Cyclists

Cyclists: Make No Bones About It BJSM 2018

Which type of exercise gives you the strongest bones? BBC

Studies

Male Cyclists: Bones, Body composition, Nutrition, Performance BJSM 2018

Longitudinal Changes in Bone Mineral Density in Male Master Cyclists and Nonathletes The Journal of Strength & Conditioning Research 2011

A meta-analysis of brief high-impact exercises for enhancing bone health in premenopausal women  Osteoporosis International 2012

Jumping Improves Hip and Lumbar Spine Bone Mass in Prepubescent Children: A Randomized Controlled Trial JBMR 2001

Review Exercise and Sports Science Australia (ESSA) position statement on exercise prescription for the prevention and management of osteoporosis Journal of Science and Medicine in Sport 2016

Resistance training is associated with higher bone mineral density among young adult male distance runners independent of physiological factors The Journal of Strength & Conditioning Research 2018

Relative Energy Deficiency in Sports (RED-S) Practical considerations for endurance athletes

Nothing Boring About Boron Integrated Medicine 2015

Cumulative Endocrine Dysfunction in Relative Energy Deficiency in Sport (RED-S) BJSM 2018

Cyclists: Make No Bones About It

Competitive cyclists are potentially at risk of suboptimal bone health. Although cycling is excellent for cardiovascular fitness, this type of non skeletal loading exercise does not mechanically stimulate osteogenesis (bone formation). This situation of low mechanical osteogenic stimulus to build bone can be compounded by restrictive eating patterns and associated hormone dysfunction of relative energy deficiency in sports (RED-S).

In a recent pilot study 7/10 competitive cyclists (Cat 2 and above) had low age-matched bone mineral density (BMD) in the lumbar spine. This is comparable to another study where 15/28 male cyclists training over eight hours a week were found to have low BMD for their age and were therefore at risk of low trauma fracture. However, cyclists with a lower training volume (Cat 4) did not fair so badly in terms of BMD, due to higher body mass index (BMI) and fat mass. Although greater body mass mechanically loads the skeleton, the downside is that you need to generate more power to get up a hill.

Why is cycling unique compared to other sports where an important adaptation to training is to improve, not impair, bone health? What are the practical solutions to prevent this potential negative effect of cycle training?

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Site Specific Effects on Bone Mineral Density

The illustration shows how different sports exert site specific effects on the bone mineral density of the skeleton. In general terms, hip femoral neck BMD is more dependent on mechanical loading osteogenic stimuli, whereas lumbar spine BMD is more dependent on nutritional and Endocrine status.

What are the most effective mechanical osteogenic stimuli? Evidence from animal models demonstrates that bone responds to exercise that is dynamic, non-repetitive and unpredictable. Load and repetitions are not such important factors. This is shown in a study of track and field athletes, where sprinters were found to have higher BMD at load bearing sites of the skeleton than long distance runners due to a local loading effect rather than a systemic effect associated with repetitive loading nature of longer distance running. The other important consideration is that sprinters and rugby players tend to weigh more with higher lean mass than distance runners, providing higher skeletal loading forces. These differences in anthropometric and body composition metrics are also associated with different nutritional and Endocrine status.

In contrast to sports involving running, rowing creates a mechanical osteogenic stimulus that is directed through the lumbar spine, resulting in an associated increase in BMD at this site. This site specific effect of rowing can prevent bone loss at the lumbar that would be anticipated with rowers experiencing RED-S.

Swimming and cycling are similar in that both these types of exercise do not provide mechanical skeletal loading osteogenic stimulus. However the consequences on BMD, particularly at the lumbar spine, can be compounded in cycling by the performance advantage of low body mass and therefore potential of restrictive nutrition and consequent effect on Endocrine status: factors which impact bone health.

In the recent pilot study of competitive cyclists, although 7/10 had below average for age lumbar spine BMD, those with stronger bones had a previous history of other sports that improve BMD at this site: namely rugby and rowing, together with the cyclist doing concurrent and consistent weight training throughout the season. These findings were consistent with a study where male riders who had undertaken pre-season weight training had better BMD than riders who had not. Cumulative skeletal loading over a lifetime determines BMD. However, the skeletal system is dynamic and as with any training adaptation, any beneficial effects of skeletal loading exercise are reversible if not maintained throughout the lifespan.

Typically, the objective of off-bike strength and conditioning (S&C) is aimed at producing higher watts on the bike. Some strengthening exercises may, as by product, produce an osteogenic stimulus indirectly by muscle pulling on bone. Should off-bike work include specific mechanical axial skeletal loading exercises that are continued throughout the season? Skeletal loading exercises for cyclists would have to be effective and practical, not requiring access to gym and possible to fit into training schedule throughout the season. This will be investigated in an forthcoming study of competitive male cyclists.

In meantime there will be more discussion on “Health, Hormones and Human Performance” at the BASEM conference 22 March. All welcome, including athletes and coaches, alongside healthcare professional working with athletes.

References

Male Cyclists: bones, body composition, nutrition, performance

Cycling and bone health: a systematic review BMC Medicine 2012

Male Athletes: the Bare Bones of Cyclists

Comparisons of Bone Mineral Density Between Recreational and Trained Male Road Cyclists Clinical Journal of Sport Medicine 2016

Longitudinal Assessment of Bone Mineral Density and Body Composition in Competitive Cyclists Journal of Strength and Conditioning Research 2017

Kings and Queens of the Mountains Science4Perforamnce

Inhibition of osteopenia by low magnitude, high-frequency mechanical stimuli Drug Discovery Today 2001

Bone density and neuromuscular function in older competitive athletes depend on running distance Osteoporosis International 2012

Menstrual state and exercise as determinants of spinal trabecular bone density in female athletes BMJ 1990

Male Athletes: the Bare Bones of Cyclists

Resistance Training Is Associated With Higher Lumbar Spine and Hip Bone Mineral Density in Competitive Male Cyclists Journal of Strength and Conditioning Research 2018

A meta-analysis of brief high-impact exercises for enhancing bone health in premenopausal women  Osteoporosis International 2012

Jumping Improves Hip and Lumbar Spine Bone Mass in Prepubescent Children: A Randomized Controlled Trial JBMR 2001

Longitudinal Changes in Bone Mineral Density in Male Master Cyclists and Nonathletes The Journal of Strength & Conditioning Research 2011

 

 

Male Athletes: the Bare Bones of Cyclists

Chris Boardman is an Olympic gold medal winner and world record breaking cyclist. However, he explains in his biography that he retired in his early thirties with weak bones and low testosterone. At the time he was treated with medication aimed at improving his bone strength, but this severely impacted his performance on the bike.

What was the cause of this superlative male athlete’s unhealthy condition that ultimately lead to his retirement? Is this still an issue for male cyclists today? Is it limited to elite professional riders?

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Periodisation of key training factors support the Endocrine system to optimise performance

In 2014 the IOC published a description of relative energy deficiency in sports (RED-S), where nutrition intake is insufficient to cover training demands and the basic “housekeeping” activities of the body. This induces an energy-saving mode that impacts health and therefore athletic performance. The female athlete triad had been previously described as the combination of disordered eating, menstrual disruption and impaired bone health. RED-S goes beyond the female athlete triad to include a broader range of  impacts on systems other than just the bones and female hormone production. Significantly RED-S includes male athletes. Today, Chris Boardman would be diagnosed with RED-S.

Has this new information improved the identification and support of male athletes at risk of RED-S? In a recent pilot study, 5 out of 10 competitive amateur riders (Category 2 and above) were in the lowest age-matched percentile of body fat and 9 out 10 where in the lowest 6% relative to the population of similar age. Significantly, 7 out of 10 riders had below-average for age bone mineral density (BMD) in the lumbar spine, with two males having bone densities that would be low for an 85 year old.

Why is poor bone health a particular risk for competitive male cyclists? Depending on the type of exercise, beneficial adaptations include mechanical strengthening of specific parts of the skeletal system. For example, assuming good nutrition, runners tend to have strong hips, whereas rowers have more robust spines in terms of BMD and bone microarchitecture. Conversely the non-weight-bearing nature of cycling and the generally lower level of upper-body musculature reduce the mechanical loading forces though the spine: low osteogenic (bone building) stimuli. Although similar to swimming, in the sense that body weight is supported in the water, the major difference between these two forms of exercise is that in cycling, particularly for climbing, low body mass confers a performance advantage. This brings in the additional factor for bone health of potential inadequacies in nutrition and therefore consequences on hormone production.

An optimal balance of training, nutrition and recovery drives beneficial adaptations to exercise throughout the body. The body’s Endocrine system releases hormones that stimulate positive changes, such as the process of improving the efficiency of delivering and utilising oxygen and nutrients to exercising tissues, including the skeletal system. Any imbalances in periodisation between the three inputs of training, nutrition and recovery will compromise health and athletic performance.

Cyclists are at particular risk of insufficient fuelling. This may be an intentional attempt to maintain low body weight, which can lead to healthy eating becoming an unhealthy orthorexic pattern, where vital food groups for endurance sport, such as carbohydrates are excluded. There is also a practical element to fuelling adequately during long rides and refuelling afterwards. Consistency of nutrition throughout the day has been highlighted in a recent study of male endurance athletes where although an average 24 hour intake may be sufficient, if there are any significant deficits during this time, then this is reflected in increased adverse impact on catabolic Endocrine makers. In another study of male athletes if refuelling with carbohydrate and protein after training did not occur promptly, this lead to an increase in bone resorption over formation markers.

Recovery is an essential part of a training schedule, because the adaptations to exercise occur during rest. Sleep, in particular, is a major stimulus for growth hormone release, which drives positive adaptive changes in terms of body composition and bone turnover. Conversely, insufficient recovery time due to a packed schedule of training and work, places extra stresses on the Endocrine system. Getting to bed half an hour earlier than usual every day quickly adds up to an extra night’s sleep.

Does it matter if some areas of the skeleton are weaker than others? Yes, because this increases your risk of fracture, not just if you come off your bike, but also with relatively low force impacts. In the case of runners and triathletes, bone stress injuries are more likely to occur as an early warning sign of impaired bone health due to RED-S. Since low impact forces are absent in cycling, it may take a crash to reveal the strength of a rider’s bones. Studying the list of injuries in elite cyclists there are many fractures, with longer recovery time for vertebral fractures. So potentially cyclists can develop more severe bone health issues than other athletes, before becoming aware of the situation.

If you are a male cyclist, what can you do to prevent issues of bone health and risk of developing RED-S and suboptimal performance on the bike? Watch this space! A study is planned to investigate practical and effective strategies to optimise health and performance on the bike. In meantime there will be more discussion on “Health, Hormones and Human Performance” at the BASEM conference 22 March. All welcome, including athletes and coaches, alongside healthcare professional working with athletes.

References

Mechanisms for optimal health…for all athletes! BJSM 2017

Optimal health: including female athletes! Part 1 Bones BJSM 2017

Optimal health: including male athletes! Part 2 Relative Energy Deficiency in sports BJSM 2017

Lifestyle Choices for optimising health: exercise, nutrition, sleep BJSM 2017

Sports Endocrinology – what does it have to do with performance? BJSM 2017

Relative Energy Deficiency in Sports (RED-S) Practical considerations for endurance athletes

Within-day Energy Deficiency and Metabolic Perturbation in Male Endurance Athletes International Journal of Sport Nutrition and Exercise Metabolism 2018

The Effect of Postexercise Carbohydrate and Protein Ingestion on Bone Metabolism Translational Journal of the American College of Sports Medicine 2017

Sleep for health and sports performance BJSM 2017

 

 

 

Cumulative Endocrine Dysfunction in Relative Energy Deficiency in Sport (RED-S)

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Unfortunately I continue to see athletes, both male and female, whose health and athletic performance is hampered due to Relative Energy Deficiency in Sports (RED-S). There have been some high profile athletes who have been very open about how RED-S has affected them, alerting younger athletes to potential pitfalls.

Does this issue warrant highlighting? Yes! The athletes I see and those that speak out are only just the tip of the iceberg. In a study of exercising females, half were found to have subtle menstrual hormone disruption such as luteal phase deficit or anovulation. A third were amenorrhoeic, with no periods at all. All women of reproductive age, whether an athlete or not, should have regular periods, otherwise there are potential serious health and performance sequaelae. However studies in both the USA and Australia have revealed that the majority of young exercising women are not aware of the link between menstrual disruption and deleterious, potentially irreversible effects on bone health.

The impact of non-integrated periodisation of training, nutrition and recovery has evolved since the early description of the female athlete triad. The constellation of amenorrhoea, disordered eating and osteoporosis is now considered to be a clinical spectrum. In turn the female athlete triad is part of a much broader picture of RED-S, which includes adverse multi-system effects beyond bone health and is also seen in male athletes.

Although an athlete may appear healthy, what are the underlying Endocrine disruptions occurring in RED-S that ultimately will impede both optimal health and performance to full potential? In general, female exercisers are more susceptible to internal and external perturbations as the female Endocrine system is more finely balanced than in males. Nevertheless, in a study of male athletes, in the short time period after completing a training session, bone turnover was adversely affected, with an increase in markers of resorption relative to formation, if an athlete did not refuel rapidly with protein and carbohydrate. In the now classic research by Loucks, 5 days of manipulated energy restricted availability, via dietary intake and exercise output, caused disruption in LH pulsatility in previously eumenorrhoeic women. From this research and subsequent studies, not only is the reproductive axis disrupted with reduced energy availability, in addition hypothalamus-pituitary-thyroid (decreased T3) and adrenal axes (increased cortisol) and decreased IGF1 due to relative GH resistance are all disrupted. These interactive hormonal dysfunctions occur even before reduction in sex steroids. A recent study demonstrated that beyond the average energy availability over a 24 hour time window, within day energy deficits in terms of duration and magnitude are associated with a greater degree of disruption of Endocrine and metabolic markers, in particular decreased oestradiol and increased cortisol. So consistency of nutrition, not only during a training season but from day to day is vital.

Although energy availability is the crucial factor in the pathophysiology of RED-S, measuring this is not practical for all athletes in terms of accuracy and cost. Clinical menstrual status in female athletes and basic Endocrine markers are proposed as being more reliable and accessible. The Endocrine system is very sensitive to internal and external perturbations, as described above, and presages performance consequences of RED-S, such as injury. An important starting point is for all female athletes is to ask themselves: are my periods regular? This is also a vital question that coaches and parents need to consider for athletes in their care. If the answer is no, then this needs to be assessed, ideally by those with experience in Sports Endocrinology.

Why are these clinical and biochemical markers of Endocrine dysfunction important for athletes? Essentially there are significant health and performance implications for athletes. As outlined in the stories of female athletes, by the time career limiting stress fractures become obvious, typically in early twenties, the Endocrine system has been in disarray for a significant time. Long term, irreversible poor bone health and adverse body composition have been established.

In my opinion, emphasis should be placed on the positive outcome of integrating periodised training, nutrition and recovery to support a functional Endocrine system and therefore optimal health and ability to reach full athletic potential. For example for female athletes, competing in sports where low body mass confers a performance advantage, such as ballet, gymnastics and road cycling, finely tuned neuromuscular skills are essential to reach maximal potential and minimise injury risk. Yet these are the athletes most at risk of developing RED-S, with consequential adverse effects on menstrual cycles, endogenous oestrogen secretion and neuromuscular function.

Rather than reading headlines about the concerning health issues amongst athletes, more guidance for athletes and those working with them, on the warning signs and how to combat RED-S are needed so that athletes can reach their full potential and the headlines become about athlete achievements.

For more discussion on the Endocrine and Metabolic aspects of Sport and Exercise Medicine, all members of multi-disciplinary team working with athletes, including athletes and coaches are welcome to the BASEM Spring Conference

BAsem2018_SpringConf_BJSM

References

Relative Energy Deficiency in Sports (RED-S) Practical considerations for endurance athletes

British middle-distance runner Bobby Clay is struggling with osteoporosis but wants her experience to act as a lesson for fellow young athletes Athletics Weekly 2017

In a special AW report, former English Schools champion Jen Walsh reveals the devastation that the female athlete triad can wreak Athletics Weekly 2017

Optimal Health: Especially Young Athletes! Part 3 – Consequences of Relative Energy Deficiency in Sports BASEM 2017

Prevalence High prevalence of subtle and severe menstrual disturbances in exercising women: confirmation using daily hormone measures. Human Repro 2010

Energy deficiency, menstrual disturbances, and low bone mass: what do exercising Australian women know about the female athlete triad? Int J Sport Nutr Exerc Metab. 2012

Female adolescent athletes’ awareness of the connection between menstrual status and bone health J Pediatr Adolesc Gynecol. 2011

Optimal health: including female athletes! Part 1 Bones BJSM 2017

Optimal Health: For All Athletes! Part 4 – Mechanisms BASEM 2017

Optimal health: including male athletes! Part 2 Relative Energy Deficiency in sports BJSM 2017

Sports Endocrinology – what does it have to do with performance? BJSM 2017

The Effect of Postexercise Carbohydrate and Protein Ingestion on Bone Metabolism Translational Journal of the American College of Sports Medicine 2017

Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women JCEM 2003

Within-day energy deficiency and reproductive function in female endurance athletes Scandinavian Journal of Science and medicine in Sports 2017

Low Energy Availability is Difficult to Assess But Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes Sports Nutrition and Exercise Metabolism 2017

Body Composition for Health and Sports Performance

Reduced Neuromuscular Performance in Amenorrheic Elite Endurance Athletes Medicine & Science in Sports & Exercise 2017

Health and Performance during Lifespan: latest research

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Your lifespan depends on genetic and key lifestyle choices

Lifespan is dependent on a range of genetic factors combined with lifestyle choices. For example a recent study reported that an increase in one body mass index unit reduced lifespan by 7 months, whilst 1 year of education increased lifespan by 11 months. Physical activity was shown to be a particularly important lifestyle factor through its action on preventing age-related telomere shortening and thus reducing of cellular ageing by 9 years. Nevertheless, even though males and females have essentially identical genomes, genetic expression differs. This results in different disease susceptibilities and evolutionary selection pressures. More studies involving female participants are required!

Circadian clock

Much evidence is emerging about the importance of paying respect to our internal biological clocks when considering the timing of lifestyle factors such as eating, activity and sleep. For example intermittent fasting, especially during the night, and time restricted eating during the day enables metabolic flexibility. In other words, eating within a daylight time window will support favourable metabolism and body composition. No midnight snacks!

For athletes, even more care needs be given to timing of nutrition to support athletic performance. In the short term there is evidence that rapid refuelling after training with a combination of carbohydrate and protein favours a positive balance of bone turnover that supports bone health and prevents injury in the longer term. Periodised nutrition over a training season, integrated with exercise and recovery, is important in order to benefit from training adaptations and optimise athletic performance.

Protein intake in athletes and non athletes

Recovering from injury can be a frustrating time and some athletes may be tempted to reduce food intake to compensate for reduced training. However, recommendations are to maintain and even increase protein consumption to prevent a loss of lean mass and disruption of metabolic signalling. In the case of combined lifestyle interventions, such as nutrition and exercise aimed at reducing body weight, these should be directed at improving body composition. Adequate protein intake alongside exercise will maintain lean mass in order to minimise the risk of sarcopenia and associated bone loss which can occur during hypocaloric regimes. Good protein intake is important for bone health to support bone mineral density and reduce the risk of osteoporosis and fracture.

Adolescent Athlete

In the young athlete, integrated periodisation of training, nutrition and recovery is of particular importance, not only to support health and performance, but as an injury prevention strategy.  Sufficient sleep and nutrition to match training demands are key.

Differences between circadian phenotype and performance in athletes

For everyone, whether athlete or reluctant exerciser, balancing and timing key lifestyle choices of exercise, nutrition and sleep are key for optimising health and performance. However there are individual differences when it comes to the best time for athletes to perform, according to circadian phenotype/chronotype. In other words personal biological clocks which run on biological time. An individual’s performance can vary by as much as 26% depending on the time of day relative to one’s entrained waking time.

Later in Life

Ageing can be can be confused with loss of fitness and ability to perform activities of daily living. Although a degree of loss of fitness does occur with increasing age, this can be prevented to a certain degree and certainly delayed with physical activity. Exercise attenuates sarcopenia, which supports bone mineral density with the added benefit of improved proprioception, helping to reduce risk of falls and potential fracture; not to mention the psychological benefits of exercise.

 

For more discussion on Health Hormones and Human Performance come to British Association of Sport and Exercise Medicine Spring Conference 

BAsem2018_SpringConf_BJSM

References

Genome-wide meta-analysis associates HLA-DQA1/DRB1 and LPA and lifestyle factors with human longevity Nature Communications 2017

Physical activity and telomere length in U.S. men and women: An NHANES investigation Preventive Medicine 2017

The landscape of sex-differential transcriptome and its consequent selection in human adults BMC Biology 2017

Temporal considerations in Endocrine/Metabolic interactions Part 1 British Journal of Sport and Exercise Medicine, October 2017

Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting Obesity 2017

Temporal considerations in Endocrine/Metabolic interactions Part 2 British Journal of Sport and Exercise Medicine, October 2017

Time-restricted eating may yield moderate weight loss in obesity Endocrine Today 2017

The Effect of Postexercise Carbohydrate and Protein Ingestion on Bone Metabolism Translational Journal of the American College of Sports Medicine 2017

Periodized Nutrition for Athletes Sports Medicine 2017

Internal Biological Clocks and Sport Performance British Journal of Sport and Exercise Medicine, October 2017

Nutritional support for injuries requiring reduced activity Sports in Science Exchange 2017

Balance fat and muscle to keep bones healthy, study suggests NTU October 2017

Dietary Protein Intake above the Current RDA and Bone Health: A Systematic Review and Meta-Analysis Journal of the American College of Nutrition 2017

Too little sleep and an unhealthy diet could increase the risk of sustaining a new injury in adolescent elite athletes Scandinavian Journal of Medicine & Science in Sports

Sleep for health and sports performance British Journal of Sport and Exercise Medicine, 2017

The impact of circadian phenotype and time since awakening on diurnal performance in athletes Current Biology

Successful Ageing British Association of Sport and Exercise Medicine 2017

Focus on physical activity can help avoid unnecessary social care BMJ October 2017

Biochemical Pathways of Sarcopenia and Their Modulation by Physical Exercise: A Narrative Review Frontiers in Medicine 2017

 

Successful Ageing

As I am discovering, ageing is an inevitable process. However what can you do to keep as healthy as possible in order to get the most out of life?

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If you are a Masters athlete, you will know that moving into these age groups means it is advisable to change training emphasis in order to prevent injury and compete successfully. As discussed at the recent conference Royal Society of Medicine on Sports Injuries and Sports Orthopaedics, during the session on “The Ageing Athlete”, older athletes need a longer dynamic warm up with controlled mobilisation and muscle activation, together with strength and conditioning sessions to prevent injury. Moving into next age group every five years gives the opportunity to assess and modify training accordingly.

Childhood development has an impact on long term adult health. Essentially the most rapid changes and potential peaks attained during childhood and adolescence reflect optimal physical and cognitive functioning in later life. The evidence from population cohort studies was presented by Professor Diana Kuh, director of MRC Unit for Lifelong Health and Ageing, at the recent conference at the Royal Society of Medicine. Up to 66% of the decline in functional ability in ageing adults is related to childhood development. In the case of pubertal timing, Professor Kuh described that delay causes 20% reduction of volumetric trabecular bone accrual. In my 3 year longitudinal study of 87 pre and post pubertal girls, high levels of training delayed menarche and blunted attainment of peak bone mass (PBM). Conversely an optimal level of training did not delay menarche and improved bone mineral density compared to age marched sedentary controls. A similar long term effect is seen in older female athletes who have experienced amenorrhoea of more than 6 months duration. Even after retirement and resumption of menses pre-menopause, irreversible loss of bone mineral density (BMD) is seen. Professor Kuh argued for specific and personalised recommendations to individuals to support successful ageing.

From a personalised medical perspective, what about hormonal changes associated with ageing? Although in men testosterone levels decline with age, nevertheless the change is more dramatic in women at menopause where the ovaries stop producing oestrogen and progesterone. This results in increased risk after the menopause of osteoporosis, cardiovascular disease and stroke, together with other vasomotor symptoms and mood changes. With increased life expectancy comes an increasing number of women with menopausal symptoms and health issues which can negatively impact on quality of life. What about hormone replacement therapy (HRT)? HRT improves menopausal symptoms and reduces the risk of post menopausal long term health problems, provided HRT is started within ten years after the menopause. After this window of opportunity replacement oestrogen can actually accelerate cell damage. As with any medical treatment there will be those for whom HRT is contra-indicated. Otherwise the risk:benefit ratio for each individual has to be weighed up so that women can arrive at an informed decision. Regarding the risk of breast cancer, this is increased by 4 cases per 1,000 women aged 50-59 years on combined HRT. This compares to an additional 24 cases in women who have body mass index (BMI)>30 and are not on HRT. This underlines the important of lifestyle which is crucial in all areas of preventative medicine.

What type of HRT has the most favourable risk:benefit ratio? Oral preparations undergo first pass metabolism in the liver, so other routes of delivery such as transdermal may be preferred. There is also an argument that hormones with identical molecular structure are preferable to bio-similar hormones. What functional effect could a slight difference in sex steroid structure have? For example no methyl group and a side chain with hydroxyl group (C-OH) rather than a carbonyl group (C=O)? That is the difference between oestradiol and  testosterone.

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Testosterone
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Oestradiol

In the case of hormones with identical molecular structure to those produced endogenously, there are no potential unwanted side effects or immunogenic issues as the molecule is identical to that produced by the body. Although the oestradiol component in most HRT preparations in the UK has an identical molecular structure to endogenous oestradiol, there is only one licensed micronised progesterone preparation that is has an identical molecular structure. Synthetic, bio-similar progestins have additional glucocorticoid and androgenic effects compared to molecular identical progesterone which exerts a mild anti-mineralocorticoid (diuretic) effect.

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Progesterone
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Norethisterone (synthetic progestin)

With an increasing ageing population and increase in life expectancy, it is important to support successful ageing and quality of life with a personalised and specific approach.

For further discussion on Endocrine and Metabolic aspects of SEM come to the BASEM annual conference 22/3/18: Health, Hormones and Human Performance

References

Conference Royal Society of Medicine 17/1/17 “Sports Injuries and Sports Orthopaedics” Session on “The Ageing Athlete”

Optimal health: especially young athletes! Part 3 Consequences of Relative Energy Deficiency in sports Dr N. Keay, British Association Sport and Exercise Medicine

From population based norms to personalised medicine: Health, Fitness, Sports Performance Dr N. Keay, British Journal of Sport Medicine 22/2/17

Optimal health: including female athletes! Part 1 Bones Dr N. Keay, British Journal of Sports Medicine

Bio-identical hormone replacement therapy course. Marion Gluck Training Academy 27/1/17

The British Menopause Society

Royal College of Obstetricians and Gynaecologists 

Optimal health: for all athletes! Part 4 Mechanisms

As described in previous blogs, the female athlete triad (disordered eating, amenorrhoea, low bone mineral density) is part of Relative Energy Deficiency in sports (RED-S). RED-S has multi-system effects and can affect both female and male athletes together with young athletes. The fundamental issue is a mismatch of energy availability and energy expenditure through exercise training. As described in previous blogs this situation leads to a range of adverse effects on both health and sports performance. I have tried to unravel the mechanisms involved. Please note the diagram below is simplified view: I have only included selected major neuroendocrine control systems.

REDs

Low energy availability is an example of a metabolic stressor. Other sources of stress in an athlete will be training load and possibly inadequate sleep. These physiological and psychological stressors input into the neuroendocrine system via the hypothalamus. Low plasma glucose concentrations stimulates release of glucagon and suppression of the antagonist hormone insulin from the pancreas. This causes mobilisation of glycogen stores and fat deposits. Feedback of this metabolic situation to the hypothalamus, in the short term is via low blood glucose and insulin levels and in longer term via low levels of leptin from reduced fat reserves.

A critical body weight and threshold body fat percentage was proposed as a requirement for menarche and subsequent regular menstruation by Rose Frisch in 1984. To explain the mechanism behind this observation, a peptide hormone leptin is secreted by adipose tissue which acts on the hypothalamus. Leptin is one of the hormones responsible for enabling the episodic, pulsatile release of gonadotrophin releasing hormone (GnRH) which is key in the onset of puberty, menarche in girls and subsequent menstrual cycles. In my 3 year longitudinal study of 87 pre and post-pubertal girls, those in the Ballet stream had lowest body fat and leptin levels associated with delayed menarche and low bone mineral density (BMD) compared to musical theatre and control girls. Other elements of body composition also play a part as athletes tend to have higher lean mass to fat mass ratio than non-active population and energy intake of 45 KCal/Kg lean mass is thought to be required for regular menstruation.

Suppression of GnRH pulsatility, results in low secretion rates of pituitary trophic factors LH and FSH which are responsible for regulation of sex steroid production by the gonads. In the case of females this manifests as menstrual disruption with associated anovulation resulting in low levels of oestradiol. In males this suppression of the hypothamlamic-pituitary-gonadal axis results in low testosterone production. In males testosterone is aromatised to oestradiol which acts on bone to stimulate bone mineralisation. Low energy availability is an independent factor of impaired bone health due to decreased insulin like growth factor 1 (IGF-1) concentrations. Low body weight was found to be an independent predictor of BMD in my study of 57 retired pre-menopausal professional dancers. Hence low BMD is seen in both male and female athletes with RED-S. Low age matched BMD in athletes is of concern as this increases risk of stress fracture.  In long term suboptimal BMD is irrecoverable even if normal function of hypothamlamic-pituitary-gonadal function is restored, as demonstrated in my study of retired professional dancers. In young athletes RED-S could result in suboptimal peak bone mass (PBM) and associated impaired bone microstructure. Not an ideal situation if RED-S continues into adulthood.

Another consequence of metabolic, physiological and psychological stressor input to the hypothalamus is suppression of the secretion of thyroid hormones, including the tissue conversion of T4 to the more active T3. Athletes may display a variation of “non-thyroidal illness/sick euthyroid” where both TSH and T4 and T3 are in low normal range. Thyroid hormone receptors are expressed in virtually all tissues which explains the extensive effects of suboptimal levels of T4 and T3 in RED-S including on physiology and metabolism.

In contrast, a neuroendocrine control axis that is activated in RED-S is the hypothalamic-pituitary-adrenal axis. In this axis, stressors increase the amplitude of the pulsatile secretion of CRH, which in turn increases the release of ACTH and consequently cortisol secretion from the adrenal cortex. Elevated cortisol suppresses immunity and increases risk of infection. Long term cortisol elevation also impairs the other hormone axes: growth hormone, thyroid and reproductive. In other words the stress response in RED-S amplifies the suppression of key hormones both directly and indirectly via endocrine network interactions.

The original female athlete triad is part of RED-S which can involve male and female athletes of all ages. There are a range of interacting endocrine systems responsible for the multi-system effects seen in RED-S. These effects can impact on current and future health and sports performance.

For further discussion on Endocrine and Metabolic aspects of SEM come to the BASEM annual conference 22/3/18: Health, Hormones and Human Performance

References

Teaching module on RED-S for BASEM as CPD for Sports Physicians

Optimal health: including female athletes! Part 1 Bones Dr N. Keay, British Journal of Sport Medicine

Optimal health: including male athletes! Part 2 Relative Energy Deficiency in sports Dr N.Keay, British Journal of Sport Medicine 4/4/17

Optimal health: especially young athletes! Part 3 Consequences of Relative Energy Deficiency in sports Dr N. Keay, British Association of Sport and Exercise Medicine

Keay N, Fogelman I, Blake G. Effects of dance training on development,endocrine status and bone mineral density in young girls. Current Research in Osteoporosis and bone mineral measurement 103, June 1998.

Jenkins P, Taylor L, Keay N. Decreased serum leptin levels in females dancers are affected by menstrual status. Annual Meeting of the Endocrine Society. June 1998.

Keay N, Dancing through adolescence. Editorial, British Journal of Sports Medicine, vol 32 no 3 196-7, September 1998.

Keay N, Effects of dance training on development, endocrine status and bone mineral density in young girls, Journal of Endocrinology, November 1997, vol 155, OC15.

Relative Energy Deficiency in sport (REDs) Lecture by Professor Jorum Sundgot-Borgen, IOC working group on female athlete triad and IOC working group on body composition, health and performance. BAEM Spring Conference 2015.

Mountjoy M, Sundgot-Borgen J, Burke L, Carter S, Constantini N, Lebrun C, Meyer N, Sherman R, Steffen K, Budgett R, Ljungqvist A. The IOC consensus statement: beyond the Female Athlete Triad-Relative Energy Deficiency in Sport (RED-S).Br J Sports Med. 2014 Apr;48(7):491-7.

“Subclinical hypothydroidism in athletes”. Lecture by Dr Kristeien Boelaert at BASEM Spring Conference 2014 on the Fatigued Athlete

From population based norms to personalised medicine: Health, Fitness, Sports Performance Dr N. Keay, British Journal of Sport Medicine