Male Cyclists: Bones, Body composition, Nutrition, Performance

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There has been much recent coverage regarding female runners suffering with health and performance issues due to relative energy deficiency in sports (RED-S). What about male athletes? A recent article about male cyclists who explained how they developed RED-S, did not receive as sympathetic a response as articles concerning female athletes. Yet multiple Endocrine network disruption in RED-S, associated with suboptimal health and performance, is equally applicable to male and female athletes.

Although competitive road cycling is excellent for cardiovascular (CV) fitness, why are male cyclists at particular risk of impaired bone health and RED-S? Cycling is a non-weight bearing type of exercise, as is swimming, so does not provide much osteogenic (bone building) stimulus. The additional element in road cycling is that, in the short term, low body weight, with associated low body fat, confers a performance advantage. However this can lead to restrictive nutrition and RED-S, that have adverse effects on health and performance, over the longer term.

A recent study looking at bone acquisition in adolescent males found that bone mass, microarchitecture and makers of bone formation were more favourable in footballers compared with cyclists and swimmers. Swimmers had the lowest Vitamin D, presumably as this is generally an indoor sport (unless you live in Australia where outdoor 50m pools abound). Another study found reduction in femoral neck bone mineral accumulation in adolescent male cyclists compared against increases over the same time frame seen in controls.

What about adult male road cyclists? When runners and cyclists were matched for age and body weight, there were no significant differences in hormone or nutrition status, yet cyclists were 7 times more likely to have osteopenia of the lumbar spine than runners. Similar results were found in another study where competitive male road cyclists were found to have reduced lumbar spine bone mineral density (BMD) for age, despite normal levels of testosterone and insulin-like growth factor 1 (IGF1), although intriguingly an inverse correlation with lumbar spine BMD and IGF1 was found. It appears that the biomechanical stress patterns on the spine in cycling are not oesteogenic in nature, which contrasts with rowing where, although also seated, the biomechanical load exerted through the spine does provide an osteogenic effect.

In addition to the non-load bearing nature of cycling on the skeleton, restrictive nutrition can contribute to suboptimal bone health. Reducing energy availability by restricting energy intake whilst increasing training load can be a strategy, especially during pre-season training to reduce body weight and body fat. Essentially, cycling up a steep incline demands less power through the pedals if your body weight is low. Nevertheless, reducing energy availability runs the risk of developing RED-S, associated Endocrine dysfunction and suboptimal bone health, on top of the non-beneficial mechanical osteogenic effect of cycling. On a practical note, with long training rides in the saddle it can be physically and practically difficult to fuel optimally. Recent research in female athletes shows that within day energy deficits magnify hormonal disruption. Could this be a factor in male cyclists where consistent fuelling is either actively avoided and/or practically difficult?

The psychological element of disordered eating has been described amongst elite male cyclists. Male cyclists, in particular, collect many metrics associated with training and racing which could be a manifestation of a drive to perfectionism. Determination and attention to detail are laudable qualities for athletes, but there is a fine line when the balance swings to behaviours and attitudes that can be detrimental to health and performance. Even starting off with good intentions can lead to problems as seen with the growing emergence of orthorexia: “clean eating”, which, ironically, becomes detrimental to health and performance with exclusion of food groups such as carbohydrates.

Exclusively practising a non weight bearing sport such as cycling although great for CV fitness, is not so good for bone health. Does this matter? Potentially injury is more likely in bike spills, which occur both in training and competition even for the most experienced bike handler. Combined with the drive for low body weight in competitive road cycling, health and performance issues can be compounded with RED-S. What are the solutions for the cyclist to support favourable body composition and bone health, which ultimately also optimises performance? A further planned study, following a current pilot study of competitive road cyclists, aims to investigate the potential beneficial effects of strength and conditioning to load the skeleton combined with a review of nutrition. See details of next study to see if you wish to participate.

For more discussion on the Endocrine aspects of Sports and Exercise Science and Medicine, BASEM Spring conference 22 March 

References

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

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

Too healthy to ride? How clean living could slow you down Cycling Weekly 2017

Body Composition for Health and Sports Performance

Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: The PRO-BONE Study JBMR 2017

Bone Related Health Status in Adolescent Cyclists Plos 2011

Participation in road cycling vs running is associated with lower bone mineral density in men Metabolism 2008

Evaluation of the Bone Status in High-Level Cyclists Journal of Clinical Densitometry 2012

Effect of exercise training programme on bone mineral density in novice college rowers BJSM 1995

Energy Intake and Energy Expenditure of Elite Cyclists During Preseason Training Int J Sports Med 2005
Kings and Queens of the Mountains Science4Performance 2017

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

Perfectionism and Risk for Disordered Eating among Young French Male Cyclists of High Performance Perceptual and Motor Skills 2004

Kings and Queens of the Mountains Science4Performance 2017

Addiction to Exercise – what distinguishes a healthy level of commitment from exercise addiction? BJSM 2017

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

Conferences in Sport/Dance, Exercise Science and Medicine 2018

Conferences for the New Year:

BAsem2018_SpringConf_BJSM

If you are interested in any aspects of Sport/Dance, Exercise and Lifestyle Medicine here are some suggestions:

British Association of Sport and Exercise Medicine Spring Conference 22 March 2018 “Health, Hormones and Human Performance” Covering the Endocrine and Metabolic aspects of Sport, Dance, Exercise Science and Medicine. From the elite athlete to the reluctant exerciser. Aimed at all those members of the multidisciplinary team working with athletes/dancers, plus athletes/dancers and their coaches/teachers.

CPD points awarded from Faculty of Sports and Exercise Medicine FSEM

BASES British Association of Sport and Exercise Sciences CPD awarded

British Journal of Sports Medicine Quality International Education Approved

CPD points from Royal College of Physicians

CPD from REP-S

 

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Why? The balance and timing of exercise, nutrition and recovery is key to optimising health and all aspects of human performance. Intricate network interactions between the Endocrine system and metabolic signalling pathways drive these positive adaptations. However, non-integration of these lifestyle factors can disrupt signalling feedback pathways and predispose to maladaptation and potentially disease states.

What? Discussion, led by experienced clinicians and researchers will cover:

· Key role of Sports Endocrinology in health and performance

· Effects of exercise modalities on body composition and bone health

· Machine learning in interpreting biochemical & metabolomic patterns

· Endocrine & metabolic markers in assessing health & training status

· Gut metabolism in supporting health and performance

· Exercise as crucial lifestyle factor in pre-existing metabolic dysfunction

Who? This conference is relevant to all members of multidisciplinary teams supporting both reluctant exercisers and elite athletes. Medics, researchers, physiologists, physiotherapists, nutritionists, psychologists, coaches, athletes. All welcome.

Health, Hormones and Human Performance will be a conference of interest to all those involved with aspiring and elite athletes, including dancers (National Institute of Dance Medicine and Science NIDMS) and those supporting reluctant exercisers through Lifestyle Medicine.

Latest news from BASEM. Interview with BASEM Today Issue 41 – Winter 2017

 

Wales Exercise Medicine Symposium by Cardiff Sports & Exercise Medicine Society 27/1/18. This includes Dr Peter Brukner, founder of the Olympic Sports Medicine Park in Melbourne, and an afternoon session discussing the female athlete through the lifespan. CPD points applied for from the Royal College of Physicians, the Faculty of Sports and Exercise Medicine, REPs and the Royal College Of General Practitioners.

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Women in Sport and Exercise Conference 2018  13-14 June Organised by The Women in Sport and Exercise Academic Network and attracting British Association of Sport and Exercise Sciences (BASES) CPD points.

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

EnergyBalance

Introduction Relative Energy Deficiency in Sport (RED-S) has evolved from the previously described Female Athlete Triad (menstrual dysfunction, disordered eating and decreased bone mineral density). The reason for the development of this clinical model of RED-S is that it has become apparent that low energy availability, ie not eating enough calories to support the combined energy demands of health and training, has more widespread adverse impacts on health and consequently performance in athletes and dancers than previously recognised. Furthermore, the RED-S model includes both male and female athletes– so if you are a male athlete, please do not stop reading! Low energy availability can impact male and female exercises of all levels and of all ages. Young developing athletes can be at particular risk of RED-S as this represents a time of growth and development, which entails many nutritional demands, in addition to those to support training. This represents a time to set up the template for health into adulthood.

Why does RED-S occur? RED-S is particularly prevalent in sports where low body weight confers a performance advantage or for aesthetic reasons. For example: long distance running, triathlon, gymnastics, dance and cycle road racing. However, RED-S could also occur not as an intentional strategy to control body weight, but rather during cycles of increased training load where periodised nutrition has not been synchronised with the increased demand on the body.

What is RED-S? Fundamentally there is a mismatch between food intake (in terms of energy and micronutrients) and the demand for nutrition required to cover expenditure, both of exercise training and for basic “housekeeping” tasks in the body to maintain health. If there is insufficient energy availability, then the body switches into an energy saving mode. This “go slow” mode has implications for hormone production and metabolic processes, which impacts all systems throughout the body. The reason why RED-S was originally described as the Female Athlete Triad is that in women the “energy saving mode” involves menstrual periods being switched off: a pretty obvious external sign as all women of child bearing age should have periods (apart from when pregnant). Low oestrogen levels have an adverse effect on bone health, resulting in decrease in bone mineral density. This effectively renders young women at increased risk of both soft tissue and bone injury, as seen in post-menopausal women. As described in the IOC statement published 2014 and updated 2018 in British Journal of Sports Medicine , the Female Athlete Triad is now recognised as just the tip of the iceberg. Disruption of hormone levels does not only adversely impact menstrual periods and bone health. There are knock on effects impacting the immune system, cardiovascular system, muscles, nervous system, gut health and the list goes on. Importantly, it is recognised that this situation is also seen in male athletes: low energy availability resulting in adverse health and performance consequences. Although exercise/dance is known to have many beneficial effects on health, all these beneficial effects are negated by low energy availability. For example, whether or not a sport is weight bearing, which traditionally improves bone health, in RED-S the predominant effect of disrupted hormones is to decrease bone density, leading to increased fracture risk.

Male cyclists Road cyclists are doubly at risk of the detrimental effects of RED-S on bone health. Performing a non-weight bearing form of exercise deprives the skeleton of the positive effect of mechanical skeletal loading on bone health. Furthermore being low body weight is a performance advantage for road cyclists when it comes to riding up hills/mountains in order to produce higher Watts/Kg over 60 minutes (60 minute functional threshold power FTP). This puts cyclists at risk of developing low energy availability, endocrine dysfunction and consequent impairment of bone health. In weight bearing sport the warning sign of suboptimal bone health if often stress fracture. This will be absent in cyclists. Hence low energy availability may go unrecognised until a bike fall results in serious fracture and indeed fractures appears as the most common type of injury amongst cyclists. Furthermore, the lumbar spine is recognised as the site most susceptible to endocrine dysfunction in RED-S. Vertebral fracture is recorded as the type of fracture in cyclists requiring the longest time off the bike. In a recent study, it was found that the factor most indicative of 60 minute FTP, was training load and NOT low body fat. Furthermore, training in low energy availability state will not result in the expected 60 minute FTP performance. So far more effective to train with sufficient nutrition on board, rather than restricting intake which will render training less effective.

What is the significance of RED-S? Do these effects of RED-S matter? Yes: there is a detrimental effect on not only health, but on all elements of sports performance. These include an inability to improve as expected in response to training and increased risk of injury. In the long-term there are potential implications for health with inability to reach peak bone mass for young athletes and at the other end of the scale, irreversible bone loss being seen in retired athletes.

Here is a summary of the potential impact of RED-S:

• Endocrine dysfunction: decreased training response

• Metabolic disruption: decreased endurance performance

• Bone health: increased risk bone stress injuries

• Decreased functional immunity: prone to infection

• Gut malfunction: impaired absorption of nutrients

• Decreased neuromuscular co-ordination: injury risk

• Psychological impact: inability to recognise risk developing RED-S

As you can see, these adverse effects are all relevant to performance in endurance sport.

What to do if you are concerned you may have RED-S?

Health Considerations:

• Women: even if your adult weight is steady, if you are a female athlete of reproductive age whose periods have stopped, then do not ignore this! In the first instance, you need to exclude any other causes (for example polycystic ovary syndrome and other hormone issues) in conjunction with your doctor. Then take a look at how you are eating in line with your training load – see the nutritional considerations section below.

• Men: if you are a male athlete struggling to improve sport performance, then review both your training load and your periodised nutrition and recovery. If the cause is RED-S then do not wait until your sport performance drops or you get injured before taking action. You may also want to consider having your testosterone levels measured to check that these are in the normal range.

Nutritional Considerations: From colleague Jo Scott-Dalgleish BSc (Hons), mBANT, CNHC

It is important to consider whether the energy deficiency that you are experiencing is intentional or unintentional.

Intentional: you may be deliberately restricting your calorie intake to lose weight and body fat, although you are already a healthy weight, as you believe this will improve your power-to-weight ratio or run speed.

  • If you are trying to lose weight – or anxious about gaining weight – and experiencing issues with hormones (such as missing your periods or not experiencing morning erections) or bone health (such as getting a stress fracture) or finding that your performance is declining rather than improving, it may be time to seek support.
  • This is particularly important if your eating patterns have become disordered, eg exclusion of multiple food groups, binge eating and/or purging, or deliberately avoiding social situations around food.
  • Please visit the resources section of an excellent campaign website that has been put together to help athletes talk more openly about their experiences with food, disordered eating and RED-S and find help: https://trainbrave.org/resources/.
  • Another great resource to learn more about RED-S and how it can adversely affect your health is http://health4performance.co.uk/athlete-dancer/

Unintentional: eating fewer calories than your body needs when you are training hard is common in endurance athletes and often not deliberate.

  • You may not yet be experiencing the symptoms of RED-S outlined as above, but you are greatly at risk of doing so if you continue to under-eat relative to your training over a period of months or years.
  • You do not need to be losing weight to be energy deficient, as your body’s metabolism adjusts to a lower intake but compromises on other functions while your weight stays the same. For example, you may experience constipation or bloating due to slowed digestive function. Here are some tips to help you meet your energy needs.

Here are some tips to help you to better manage your energy intake if you are at unintentional risk of RED-S.

  • Track your food intake vs energy expenditure for a short period. Use My Fitness Pal or a similar app to track these daily over the course of week. On any day when you train, if you are consuming fewer than 2500 calories as a male endurance athlete and 2000 calories as a female endurance athlete after taking your energy expenditure through training into account, your intake is likely to be inadequate as these are the guidelines for the general population. Use this data to learn more about appropriate food choices and serving sizes and introduce some changes to increase your intake in line with your training load. But I do not suggest using apps like these on a long-term basis as they may encourage an unhealthy obsession with your food intake.
    • Periodise your carbohydrate intake in line with your training. Increase your intake of starches and sugars (including vegetables and fruit) on your heavier training days. A low daily carbohydrate intake might be in the range of 2-4 g/kg of body weight. This is OK for lower volume training days but should be increased to 5-8 g/kg when training for 2-3 hours or more in a single day. This would include use of sports nutrition products like bars, gels and sports drinks during training. Again, use an app like My Fitness Pal for a week to help you assess your carbohydrate intake.
  • Pay attention to your recovery nutrition. Consuming 15-25g of protein and 45-75g of carbohydrate in the hour after exercise, whether as a snack or as part of a meal will help you to each your energy intake goals, restock your glycogen stores for your next training session and protect lean muscle mass.
  • Avoid excluding foods, whole food groups or following ‘fad diets’. Unless you have a genuine allergy or a diagnosed medical condition such as coeliac disease or lactose intolerance. Or you have been advised to avoid certain foods by a dietician or other well-qualified nutrition practitioner to help manage a health condition such as Irritable Bowel Syndrome. If you are vegetarian or vegan, see my blog here [link to https://www.endurancesportsnutritionist.co.uk/blog/vegan-diets-guide-endurance-athlete/] for tips on ensuring a well-balanced approach.
  • Focus on nutrient density. Make good quality food choices to help you get enough vitamins and minerals as well as carbohydrates, protein, fat and fibre. Try to eat fresh, minimally processed foods rather than too much packaged food, including 3-5 servings of vegetables and 2-3 pieces of fresh fruit each day.

If you are experiencing relative energy deficiency, avoid following approaches like fasted training, where the training benefits are likely to be outweighed by the pitfalls of inadequate calorie intake. I also suggest avoiding low carb-high fat diets (LCHF) due to potential adverse effects on thyroid hormones, particularly T3, which may slow down metabolism and impact on performance. It can also be difficult to obtain adequate calories from these types of diets due to the near exclusion of a whole food group – which is why they may be very effective for weight loss in people who are overweight – and the lack of carbohydrate may harm performance through a loss of metabolic flexibility, ie ability to utilise carbohydrate as fuel when required for high intensity efforts.

Conferences in Sport/Dance, Exercise Science and Medicine 2018

References

Raising Awareness of RED-S in Male and Female Athletes and Dancers Dr N. Keay, British Journal of Sport Medicine 2018

2018 UPDATE: Relative Energy Deficiency in Sport (RED-S) Dr N. Keay, British Journal of Sport Medicine 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 N, Francis G, Hind K. BMJ Open Sport & Exercise Medicine 2018

Optimal health: including female athletes! Part 1 Bones Dr N. Keay, British Journal of Sport Medicine 2017

Optimal health: including male athletes! Part 2 Relative Energy Deficiency in sports Dr N. Keay, British Journal of Sport Medicine 2017

Optimal Health: Especially Young Athletes! Part 3 – Consequences of Relative Energy Deficiency in Sports Dr N. Keay, British Association of Sport and Exercise Medicine 2017

Mechanisms for optimal health…for all athletes! Dr N. Keay, British Journal of Sport Medicine 2017

The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S) British Journal of Sports Medicine 2014

Nutritional considerations for vegetarian endurance athletes Jo Scott-Dalgleish, Endurance Sports Nutrition 2017

 

Athletic Fatigue: Part 2

A degree of athletic fatigue following a training session, as described in part 1, is required to set in motion mechanisms to drive beneficial adaptations to exercise. At what point does this process of functional over-reaching tip into non-functional over-reaching denoted by failure to improve sports performance? Or further still along the spectrum and time scale, the chronic situation of overtraining and decrease in performance? Is this a matter of time scale, or degree, or both?

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Integrated Periodisation of Training Load, Nutrition and Recovery keeps an individual on the green plateau, avoiding descent into the red zone, due to an excess or deficiency

Determining the tipping point between these fatigue situations is important for health and performance. A first step is always to exclude underlying organic disease states, be these of Endocrine, systemic inflammatory or infective aetiologies. Thereafter the crucial step is to assess whether the periodisation of training, nutrition and recovery are integrated over a training block and in the longer term over a training season.

What about the application of Endocrine markers to monitor training load? Although the recent studies described below are more applicable to research scenarios, they give some interesting insights into the interactive networks effects of the Endocrine system and the multifactorial nature of fatigue amongst individual athletes.

In the short term, during a 2 day rowing competition, increases in wakening salivary cortisol were noted followed by return towards baseline in subsequent 2 day recovery. Despite individual variability with salivary cortisol measurement, this does at least offer a noninvasive way to adjust training loads around competition time for elite athletes.

Over an 11 day stimulated training camp and recovery during the sport specific preparatory phase of the training season, blood metabolic and Endocrine markers were measured. In the case of an endurance based training camp in cyclists, a significant increase in urea (due to protein breakdown associated with high energy demand training) and decrease in insulin-like growth factor 1 (IGF1) from baseline were noted. Whereas for the strength-based athletes for ball sports, an increase in creatine kinase (CK) was seen, as a result of muscle damage. This study demonstrates how different markers of fatigue are specific to sport discipline and mode of training. Large inter-individual variability existed between the degree of change in markers and degree of fatigue.

In the longer term, for the case of overtraining syndrome potential Endocrine markers have been reviewed. Whilst basal levels of most measured hormones remained stable, a blunted submaximal exercise response of growth hormone (GH), prolactin and ACTH could be indicative of developing overtraining syndrome. Whilst this review is interesting, dynamic testing is not a practical approach and these findings are not specific to over training. Rather this blunted dynamic exercise response would indicate relative suppression of the neuroendocrine hypothalamic-pituitary axis which could potentially involve other stressors such as inadequate sleep or poor nutrition. Although basal levels may lie “within the normal range”, if both pituitary derived stimulating hormone and end endocrine gland hormone concentrations fall in the lower end of the normal ranges (eg low end of range TSH and T4) this is consistent with mild hypothalamic suppression observed over the range of training and fatigue conditions (functional/non-functional and overtraining) and/or Relative Energy Deficiency in Sports (RED-S).

Although the studies above are of research interest, non invasive monitoring, specific to an athlete is more practical for monitoring the effects of training. Several useful easily measurable metrics can give clues: resting heart rate, heart rate variability, power output. Tools on Strava and Training Peaks provide practical insights in monitoring training effectiveness via these metrics. A range of mobile apps makes it ever easier to augment a personal training log to include these training metrics, along with feel, sleep and nutrition. Such a log provides feedback on health and fitness for the individual athlete, in order to personalise training plans. Certainly adding the results from any standard basal blood tests will also help add to the picture, along the lines of building a longitudinal personal biological passport. After all, “normal ranges” are based on the general population, of which top level athletes may represent a subgroup. The more personalised the metics recorded over a long time scale, the more sensitive and useful the process to guide improvement in sport performance.

Context is key when considering athletic fatigue: temporal considerations and individual variation. Certainly the interactive network effects of the Endocrine system are important in determining the degree of adaptation to exercise and therefore sports performance. However the Endocrine system acts in conjunction with many other systems (metabolic, immune and inflammatory), in determining the effectiveness of training in improving sports performance. So it is not surprising that one metric or marker in isolation is not predictive of fatigue status in individual athletes.

For more discussion on Health, Hormones and Human Performance come to the British Association of Sport and Exercise Medicine annual conference

Presentations

References

Athletic Fatigue: Part 1

Endocrine system: balance and interplay in response to exercise training

Temporal considerations in Endocrine/Metabolic interactions Part 1

Fatigue, sport performance and hormones..more on the endocrine system Dr N Keay, British Journal of Sports Medicine 2017

Sport Performance and RED-S, insights from recent Annual Sport and Exercise Medicine and Innovations in Sport and Exercise Nutrition Conferences Dr N Keay, British Journal of Sports Medicine 2017

Capturing effort and recovery: reactive and recuperative cortisol responses to competition in well-trained rowers British Journal of Sports Medicine

Blood-Borne Markers of Fatigue in Competitive Athletes – Results from Simulated Training Camps Plos One

Hormonal aspects of overtraining syndrome: a systematic review BMC Sports Science, Medicine and Rehabilitation 2017

Clusters of Athletes – A follow on from RED-S blog series to put forward impact of RED-S on athlete underperformance Dr N Keay, British Association of Sport and Exercise Medicine 2017

Strava Fitness and Freshness Science4Performance 2017

From population based norms to personalised medicine: Health, Fitness, Sports Performance Dr N Keay, British Journal of Sports Medicine 2017

Sports Endocrinology – what does it have to do with performance? Dr N Keay, British Journal of Sports Medicine 2017

Athletic Fatigue: Part 1

Interpreting athletic fatigue is not easy. Consideration has to be given to context and time scale. What are the markers and metrics that can help identify where an athlete lies in the optimal balance between training, recovery and nutrition which support beneficial adaptations to exercise whilst avoiding the pitfalls of fatigue and maladaptation? This blog will discuss the mechanisms of athletic fatigue in the short term.

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Proposed causes of fatigue dependent on duration and intensity of training session

In the short term, during an endurance training session or race, the temporal sequence of athletic fatigue depends on duration and intensity. It is proposed that below lactate threshold (LT1), a central mechanism governs: increasing central motor drive is required to maintain skeletal muscular power output until neuromuscular fatigue cannot be overcome. From lactate threshold (LT1) to lactate turn point (LT2), a combination of central and peripheral factors (such as glycogen depletion) are thought to underpin fatigue. During high intensity efforts, above LT2 (which correspond to efforts at critical power), accumulation of peripheral metabolites and inability to restore homeostasis predominate in causing fatigue and ultimately inability to continue, leading to “task failure”. Of course there is a continuum and interaction of the mechanisms determining this power-duration relationship. As glycogen stores deplete this impacts muscle contractility by impairing release of calcium from the sarcoplasmic reticulum in skeletal muscle. Accumulation of metabolites could stimulate inhibitory afferent feedback to central motor drive for muscle contraction, combined with decrease in blood glucose impacting central nervous system (CNS) function.

Even if you are a keen athlete, it may not be possible to perform a lactate tolerance or VO2 max test under lab conditions. However a range of metrics, such as heart rate and power output, can be readily collected using personalised monitoring devices and then analysed. These metrics are related to physiological markers. For example heart rate and power output are surrogate markers of plasma lactate concentration and thus can be used to determine training zones.

A training session needs to provoke a degree of training stress, reflected by some short term fatigue, to set in motion adaptations to exercise. At a cellular level this includes oxidative stress and exerkines released by exercising tissues, backed up by Endocrine responses that continue to take effect after completing training during recovery and sleep. Repeated bouts of exercise training, followed by adequate recovery, result in a stepwise increase in fitness. Adequate periodised nutrition to match variations in demand from training also need to be factored in to prevent the Endocrine system dysfunction seen in Relative Energy Deficiency in Sports (RED-S), which impairs Endocrine response to training and sports performance. Integrated periodisation of training/recovery/nutrition is essential to support beneficial multi-system adaptations to exercise on a day to day time scale, over successive training blocks and encompassing the whole training and competition season. Psychological aspects cannot be underestimated. At what point does motivation become obsession?

In Part 2 the causes of athletic fatigue over a longer time scale will be discussed, from training blocks to encompassing whole season.

For more discussion on Health, Hormones and Human Performance come to the British Association of Sport and Exercise Medicine annual conference

Presentations

References

Endocrine system: balance and interplay in response to exercise training

Power–duration relationship: Physiology, fatigue, and the limits of human performance European Journal of Sport Science 2016

Strava Ride Statistics Science4Performance 2017

Sleep for health and sports performance Dr N Keay, British Journal of Sports Medicine 2017

Relative Energy Deficiency in Sports (RED-S) Practical Considerations for Endurance Athletes

Sports Endocrinology – what does it have to do with performance? Dr N Keay, British Journal of Sports Medicine 2017

Optimal Health: For All Athletes! Part 4 – Mechanisms Dr N Keay, British Association of Sport and Exercise Medicine 2017

Addiction to Exercise – what distinguishes a healthy level of commitment from exercise addiction? Dr N Keay, British Journal of Sports Medicine 2017

 

 

Temporal considerations in Endocrine/Metabolic interactions Part 2

LifeSeasonDay

As discussed in the first part of this blog series, the Endocrine system displays temporal variation in release of hormones. Amplitude and frequency of hormonal secretion display a variety of time-related patterns. Integrating external lifestyle factors with this internal, intrinsic temporal dimension is crucial for supporting metabolic and Endocrine health and sport performance.

Circadian misalignment and sedentary lifestyle has been implicated in the increased incidence of metabolic syndrome driven by insulin resistance and associated metabolic inflexibility and decrease in fat oxidation. However, a recent study of overweight individuals, found that increases in fat oxidation from lifestyle intervention, corresponded to different clinical outcomes. Both those who maintained weight loss and those who regained weight displayed increased fat oxidation compared to baseline. How could this be? Increased fat oxidation is only part of the equation in overall fat balance. What adaptations in the metabolic and Endocrine networks were occurring during rest periods? In the case of those that maintained weight loss, increased fat oxidation was reflected in biochemical and physiological adaptations to enable this process. Whereas for those that regained weight in the long term, increased fat oxidation was enabled by increased availability of lipids, indicating increased fat synthesis over degradation.

Clearly there is individual variation in long-term Endocrine and metabolic responses to external factors. Focusing on optimising a single aspect of metabolism in the short term, will not necessarily produce the expected, or desired clinical outcome over a sustained period of time. As previously discussed the single most effective lifestyle change that induces synchronised, beneficial sustained Endocrine and metabolic adaptations is exercise.

It will come as no surprise that focusing on maximising use of a single substrate in metabolism, without integration into a seasonal training plan and consideration of impacts on internal control networks, has not produced the desired outcome of improved performance amongst athletes. Theoretically, increasing fat oxidation will benefit endurance athletes by sparing glycogen use for high intensity efforts. Nutritional ketosis can be endogenous (carbohydrate restricted intake) or exogenous (ingestion of ketone esters and carbohydrate). Low carbohydrate/high fat diets have been shown in numerous studies to increase fat oxidation, however, this was at the expense of effective glucose metabolism required during high intensity efforts. Potentially there could be adverse effects of low carbohydrate intake on gut microbiota and immunity.

This effect was observed even in a study on a short timescale using a blinded, placebo-controlled exogenous ketogenic intervention during a bicycle test, where glycogen was available as a substrate. The proposed mechanism is that although ketogenic diets promote fat oxidation, this down-regulates glucose use, as a respiratory substrate. In addition, fat oxidation carries a higher oxygen demand for a lower yield of ATP, compared to glucose as a substrate in oxidative phosphorylation.

Metabolic flexibility the ability to use a range of substrates according to requirement, is key for health and sport performance. For example, during high intensity phases of an endurance race, carbohydrate will need to be taken on board, so rehearsing what types/timing of such nutrition works best for an individual athlete in some training sessions is important. Equally, some low intensity training sessions with low carbohydrate intake could encourage metabolic flexibility. However, in a recent study “training low” or periodised carbohydrate intake failed to confer a performance advantage. I would suggest that the four week study time frame, which was not integrated into the overall training season plan, is not conclusive as to whether favourable long term Endocrine and metabolic adaptations would occur. A review highlighted seasonal variations in male and female athletes in terms of energy requirements for different training loads and body composition required for phases of training blocks and cycles over a full training season.

Essentially an integrated periodisation of training, nutrition and recovery over a full training season will optimise the desired Endocrine and metabolic adaptations for improved sport-specific performance. The emphasis will vary over the lifespan of the individual. The intricately synchronised sequential Endocrine control of the female menstrual cycle is particularly sensitive to external perturbations of nutrition, exercise and recovery. Unfortunately the majority of research studies focus on male subjects.

In all scenarios, the same fundamental temporal mechanisms are in play. The body seeks to maintain homeostasis: status quo of the internal milieu is the rule. Any external lifestyle factors provoke short term internal responses, which are regulated by longer term Endocrine network responses to result in metabolic and physiological adaptations.

For further discussion on Health, Hormones and Human Performance, come to the BASEM annual conference

References

Temporal considerations in Endocrine/Metabolic interactions Part 1 Dr N. Keay

Sports Endocrinology – what does it have to do with performance? Dr N.Keay, British Journal of Sports Medicine 2017

Sedentary behaviour is a key determinant of metabolic inflexibility Journal of Physiology 2017

Influence of maximal fat oxidation on long-term weight loss maintenance in humans Journal of Applied Physiology 2017

One road to Rome: Metabolic Syndrome, Athletes, Exercise Dr N.Keay 2017

Metabolic and Endocrine System NetworksDr N. Keay 2017

Nutritional ketone salts increase fat oxidation but impair high-intensity exercise performance in healthy adult males Applied Physiology, Nutrition, and Metabolism 2017

Endocrine system: balance and interplay in response to exercise training Dr N. Keay 2017

No Superior Adaptations to Carbohydrate Periodization in Elite Endurance Athletes Medicine & Science in Sports & Exercise 2017

Total Energy Expenditure, Energy Intake, and Body Composition in Endurance Athletes Across the Training Season: A Systematic Review Sports Medicine – Open 2017

Successful Ageing Dr N. Keay, British Association of Sport and Exercise Medicine 2017

Optimal Health: For All Athletes! Part 4 – Mechanisms Dr N. Keay, British Association of Sport and Exercise Medicine 2017

 

 

 

Metabolic and Endocrine System Networks

EndoMetaNetworks

What are the most effective strategies to optimise health and performance? There are ever more emerging possibilities, permutations and combinations to chose from.

The simple answer is that the most effective option will depend on your starting point and what you are trying to achieve. In all cases exercise and activity levels are the fundamental basis for health and performance. Regarding nutritional strategies to support effective exercise adaptations, no single component of your dietary intake can be considered in isolation. After all, the metabolic pathways and Endocrine axes in your body work as an interactive network, with an important temporal dimension.

Emerging evidence implicates resistance to the anabolic pancreatic hormone, insulin, as the underlying pathological process in the development of metabolic syndrome. What type of diet might drive or conversely counter this process involving metabolism and the Endocrine system? The standard approach, of calorie restriction and aggressive pharmacological treatment of raised lipids, does not produce the anticipated reduction in cardiovascular mortality. Rather the synergistic effect of a diet high in both fat and carbohydrate induces hypothalamic inflammation and dysfunction in the control system of energy metabolism. The hypothalamus is the neuroendocrine gatekeeper providing the crucial link between internal and external stimuli and homeostasis of the internal milieu through integrated Endocrine responses. Intriguingly there is as an inflammatory component to the pathogenesis of cardiovascular disease.

The interaction between metabolic, Endocrine and inflammatory networks is seen in polycystic ovary syndrome (PCOS). The clinical diagnosis of PCOS relies on two of three diagnostic criteria (menstrual disturbance, hyperandrogenism, ovarian morphology). However, the underlying metabolic disruption for all phenotypes of the condition, from overweight to slim, is insulin resistance. The link between adverse body composition, metabolic and Endocrine dysfunction has recently been described. Adipokines, a class of cytokine, including adiponectin and resistin are produced by adipose tissue and exert an effect on metabolism, including insulin sensitivity and inflammation. Changes in plasma concentrations and/or expression of adipokines are seen in metabolic dysfunction and potentially have direct and indirect effects on the hypothalmic-pituitary-gonadal axis in PCOS.

Further evidence of the crucial interaction between metabolic and Endocrine systems and health was found in a longitudinal study of children, quantifying heart rate variability and the energy and inflammatory related biomarkers leptin (atherogenic) and adiponectin (anti-atherogenic) as potential predictive markers in cardiovascular screening/prevention.

Exogenous hormones impact not only the endogenous Endocrine system, but have metabolic effects. The intended purpose of the combined oral contraceptive pill (OCP) is to suppress ovulation. Another effect on the Endocrine system is to increase production of sex hormone-binding globulin (SHBG), which binds free testosterone. This has a therapeutic effect in the treatment of PCOS to lower elevated testosterone, however this may not be such a desirable effect in female athletes, where higher range testosterone levels as associated with performance advantages in certain power events. In the case of female athletes with relative energy deficiency in sports (RED-S), use of the OCP masks underlying hypothalamic amenorrhoea and is not effective in bone health protection. Further areas where Endocrine manipulation impacts metabolism are an increase in oxidative stress with OCP use and alterations in nutritional requirements due to alteration of absorption of vitamins and minerals such as vitamin B complex and magnesium, which are vital for enzymic processes involved in energy production. Yet an elevation of ferritin as an acute phase reactant is seen. These interactions of Endocrine and metabolic networks are particularly important considerations for the female athlete.

There is no single elixir for health and performance.  We are individuals with subtle differences in our genetic and epigenetic make up, including the diversity of our microbiome. Furthermore, the Endocrine and metabolic milieu changes during our lifespan. Personalised health and performance strategies must take account of the complex, intricate interactions between the Endocrine and metabolic networks.

For further discussion on Health, Hormones and Human Performance, come to the BASEM annual conference

References

One road to Rome: Metabolic Syndrome, Athletes, Exercise Dr N.Keay

Endocrine system: balance and interplay in response to exercise training Dr N. Keay

Dietary sugars, not lipids, drive hypothalamic inflammation Molecular Metabolism June 2017

Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions British Journal of Sport and Exercise Medicine

Adiponectin and resistin: potential metabolic signals affecting hypothalamo-pituitary gonadal axis in females and males of different species Reproduction: Journal for the Society of Reproduction and Fertility 2017

Longitudinal Associations of Leptin and Adiponectin with Heart Rate Variability in Children Front. Physiol 2017

AKR1C3-mediated adipose androgen generation drives lipotoxicity in women with polycystic ovary syndrome J Clin Endocrinol Metab 2017

Hormones and Sports Performance Dr N. Keay

Mechanisms for optimal health…for all athletes! Dr N. Keay, British Journal of Sport and Exercise Medicine

Oxidative Stress in Female Athletes Using Combined Oral Contraceptives Sports Medicine – Open

Oral contraceptives and changes in nutritional requirements European Review for Medical and Pharmacological Sciences

Inflammation: Why and How Much? Dr N. Keay, British Association of Sport and Exercise Medicine 2017

 

 

Addiction to Exercise

ExerciseAddiction

Health is not just the absence of illness, but rather the optimisation of all components of health: physical, mental and social. Exercise has numerous benefits on all these aspects. However, a recent article in the British Medical Journal described how exercise addiction can have detrimental physical, mental and social effects.

Dedication and determination are valuable qualities required to be successful in life, including achieving sporting prowess. Yet, there is a fine line between dedication and addiction.

To improve sports performance, cumulative training load has to be increased in a quantified fashion, to produce an overload and hence the desired physiological and Endocrine adaptive responses. Integrated periodisation of training, recovery and nutrition is required to ensure effective adaptation. Sufficient energy availability and quality of nutrition are essential to support health and desired adaptations. On the graph above the solid blue line represents a situation of energy balance, where the demands of increased training load are matched by a corresponding rise in energy availability. This can be challenging in sports where low body weight confers a performance or aesthetic advantage, where the risk of developing relative energy deficiency in sport (RED-S) has implications for Endocrine dysfunction, impacting all aspects of health and sports performance.

Among those participating in high volumes of exercise, what distinguishes a healthy level of commitment from exercise addiction? Physical factors alone are insufficient: all those engaging in high levels of training can experience overuse injuries and disruption in Endocrine, metabolic and immune systems. Equally, in all these exercising individuals, overtraining can result in underperformance.

Psychological factors are the key distinguishing features between the motivated athlete and the exercise addict. In exercise addiction unhealthy motivators and emotional connection to exercise can be identified as risk factors. In exercise addiction the motivation to exercise is driven by the obsession to comply with an exercise schedule, above all else. This can result in negative effects and conflict in social interactions, as well as negative emotional manifestations, such as anxiety and irritability if unable to exercise, including the perceived necessity to exercise even if fatigued or injured.

Two categories of exercise addiction have been described. Primary exercise addiction is the compulsion to follow an excessive training schedule. Without balancing energy intake, the physical consequence may be a relative energy deficiency, as indicated on the graph by the dashed blue line. In secondary exercise addiction, the situation is compounded by a desire specifically to control body weight. These individuals consciously limit energy intake, almost inevitably developing the full clinical syndrome described in RED-S, dragging them down to the position indicated by the dotted blue line on the chart. These situations of exercise addiction can lead to varying risk categories of RED-S.

As described at the start of this blog, there is a blurred boundary between the dedicated athlete and the exercise addict. In practice there is most likely a cross over. For example, an athlete may start with healthy motivators and positive emotional connection to exercise, which can become a primary addiction to adhere rigidly to a training schedule, rather than putting the emphasis on the outcome of such training. In the case of an athlete where low body weight is an advantage, it is easy to appreciate how this could become a secondary exercise addiction, where the motivation for exercising becomes more driven by the desire to control weight, rather than performance.

In order to support those with exercise addiction, discussion needs to focus on adopting a more flexible approach to exercise, by recognising that exercise addiction has detrimental effects on all aspects of current and long term health. Furthermore, in the case of athletes, a multi-disciplinary approach is desirable to help the individual refocus on the primary objective of training: to improve performance. In all situations, discussion should explore modifications to exercise and nutrition, in order to prevent the negative effects of RED-S on health and performance.

Exercise has numerous health benefits and is usually viewed as positive behaviour. However, the outcome of exercise is related to the amount of training, appropriate nutrition and motivation for exercising.

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

Addiction to Exercise British Medical Journal 2017

Clusters of Athletes British Association of Sport and Exercise Medicine 2017

Sport performance and relative energy deficiency in sport British Journal of Sport Medicine 2017

Balance of recovery and adaptation for sports performance British Association of Sport and Exercise Medicine 2017

Optimal Health for all athletes Part 4 Mechanisms of RED-S British Journal of Sport Medicine 2017

Sports Endocrinology – what does it have to do with performance? British Journal of Sport Medicine 2017

Inflammation: Why and How Much? British Association of Sport and Exercise Medicine 2017

Fatigue, Sport Performance and Hormones…

How do you feel on Monday morning, when the alarm wakes you at 7am with a day of work ahead after the weekend? A bit tired, slightly lethargic, sluggish, maybe a little bit down, perhaps a few regrets about somewhat too much alcohol/food over weekend, frustrated that the exercise training schedule didn’t go according to plan?sleep

There are many causes of fatigue and sport underperformance: Endocrine, immunological, infective, metabolic, haematological, nutritional, digestive, neoplastic….. The adrenal gland in the Endocrine system in particular has come in for some bad press recently.

Adrenal woes

Undoubtedly the adrenal glands have a case to answer. Situated above the kidneys these Endocrine glands produce glucocorticoids, mineralocorticoids, androgens from the adrenal cortex and from the adrenal medulla adrenaline. Glucocorticoids (e.g. cortisol) have a metabolic function to maintain energy homeostasis and an immune function to suppress inflammation. Mineralocorticoids (e.g. aldosterone) maintain electrolyte and water balance. As mineralocorticoids and glucocorticoids are similar biological steroid molecules, there is some degree of overlap in their actions.

Addison’s disease and Cushing’s disease are serious medical conditions, corresponding respectively to under or over production by the adrenal glands of steroid hormones. Someone presenting in Addisonian crisis is a medical emergency requiring resuscitation with intravenous hydrocortisone and fluids. Conversely those with Cushing’s can present with hypertension and elevated blood glucose. Yet, apart from in the extremes of these disease states, cortisol metrics do not correlate with clinical symptoms. This is one reason why it is unwise and potentially dangerous to stimulate cortisol production based on clinical symptoms. Inappropriate exogenous steroid intake can suppress normal endogenous production and reduce the ability to respond normally to “stress” situations, such as infection. This is why the prescription of steroids, for example to reduce inflammation in autoimmune disease, is always given in a course of reducing dose and a steroid alert card has to be carried. Athletes should also be aware that exogenous steroid intake is a doping offence.

However, what is the “normal” concentration for cortisol? Well, for a start, it depends what time of day a sample is taken, as cortisol is produced in a circadian rhythm, with highest values in the morning on waking and lowest levels about 2/3am. Nor is this temporal periodicity of production the only variable, there are considerations such as tissue responsiveness and metabolism (break down) of the hormone. On top of these variables there are other inputs to the feedback control mechanism, which can in turn influence these variables. In other words, focusing on the steroid hormone production of the adrenal gland in isolation, could overlook underlying hypothamalmic-pituitary-adrenal (H-P-A) axis dysfunction and indeed wider issues.

Much maligned thyroid

That is not end of the possible causes of fatigue and sport underperformance: the H-P-A axis is just one of many interrelated, interacting Endocrine systems. There are many neuroendocrine inputs to the hypothalamus, the gate keeper of the control of the Endocrine system. Furthermore there are network interaction effects between the various Endocrine control feedback loops. For example cortisol towards the top end of “normal” range can impede the conversion at the tissue level of thyroxine (T4) to the more active triiodothyronine (T3) by enzymes which require selenium to function. Rather T4 can be converted to reverse T3 which is biologically inactive, but blocks the receptors for T3 and thus impair its action. This in turn can interfere with the feedback loop controlling thyroid function (hypothalamic-pituitary-thyroid axis). The physiological ratio of T4 to T3 is 14:1, which is why supplementation with desiccated thyroid is not advisable with ratio of 4:1. There are other processes which can crucially interfere with this peripheral conversion of T4 to T3, such as inflammation and gut dysbiosis, which can occur as result of strenuous exercise training. So what might appear to be a primary thyroid dysfunction can have an apparently unrelated underlying cause. Indeed amongst highly trained athletes thyroid function can show an unusual pattern, with both thyroid stimulating hormone (TSH) and T4 at low end of the “normal “range, thought to be due to resetting of the hypothalamic-pituitary control signalling system. This highlights that the “normal” range for many hormones comprises subsets of the population and in the case of TSH, the “normal” range is not age adjusted, despite TSH increasing with age. As described by Dr Boelaert at recent conferences, there is certainly no medical justification for reports of some athletes in the USA being given thyroxine with TSH>2 (when the normal range is 0.5-5mU/l). Although thyroxine is not on the banned list for athletes, it could have potentially serious implications for health due to its impact on the Endocrine system as a whole.

Endocrine system interactions

SportsEndocrinologyWordCloud

Symptoms of fatigue are common to many clinical conditions, not just dysfunction in an Endocrine control axis in isolation, nor even the network interactive effects of the Endocrine system in isolation. For example, the impact of nutrition relative to training load produces a spectrum of clinical pictures and Endocrine disturbances seen in Relative Energy Deficiency in Sport (RED-S) in terms of health and sport performance.

Underlying mechanisms of Endocrine dysfunction

There may be predisposing factors in developing any clinical syndrome, the usual suspects being inflammation: whether infective, dysbioses, autoimmune; nutritional status linked with endocrine status;  training load with inadequate periodised recovery to name a few….

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

From population based norms to personalised medicine: Health, Fitness, Sports Performance British Journal of Sport Medicine 2017

Sports Endocrinology – what does it have to do with performance? British Journal of Sport Medicine 2017

Advanced Medicine Conference, Royal College of Physicians, London 13-16 February 2017, Endocrine session: Dr Kristien Boelaert, Dr Helen Simpson, Professor Rebecca Reynolds

Subclinical hypothydroidism in athletes. Lecture by Dr Kristeien Boelaert, British Association of Sport and Exercise Medicine Spring Conference 2014. The Fatigued Athlete

Sport Performance and RED-S, insights from recent Annual Sport and Exercise Medicine and Innovations in Sport and Exercise Nutrition Conferences British Journal of Sport Medicine 2017

Relative Energy Deficiency in Sport CPD module British Association of Sport and Exercise Medicine 2017

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

Inflammation: why and how much? British Association of Sport and Exercise Medicine 2017

Clusters of athletes British Association of Sport and Exercise Medicine 2017

Enhancing Sport Performance: Part 1 British Association of Sport and Exercise Medicine 2017

Balance of recovery and adaptation for sports performance British Association of Sport and Exercise Medicine 2017

Annual Sport and Exercise Medicine Conference, London 8/3/17 Gut Dysbiosis, Dr Ese Stacey

Adrenal fatigue does not exist: a systematic review BMC Endocrine Disorders. 2016; 16(1): 48.

A Controversy Continues: Combination Treatment for Hypothyroidism Endocrine News, Endocrine Society April 2017