Overtraining revisited from an integrative perspective – Ian Craig

Overtraining is a well-studied phenomenon in sports medicine, but it may also be viewed as adrenal fatigue in integrative health practices. Ian Craig pulls together a few physiological models and considerations to help us understand this term better. 

Overtraining interests me a lot, not just because during my own athletic career, I often pushed my own boundaries, but because if you take away the word ‘training’, you’re left with over (or excess), meaning that this phenomenon is influenced by each and every one of our daily behaviours. Overtraining starts to merge with health imbalances such as burnout, adrenal fatigue or exhaustion, immune compromise, and the more complicated myriad of health complications, such as chronic fatigue, fibromyalgia and autoimmunity.

In the recent words of my overtrained long-distance trail running client, whom I will call Roger: “I have come down with a cold, and I am man down. I lasted one month in 2018 before I got ill. I am incredibly frustrated with my health and feel betrayed by my body. Despite a healthier diet, supplements and slightly more rest, I am still getting sick.” Like most of the athletes I see in my practice, Roger viewed his body like a machine – if I put a, b, c into it, I should get x, y and z out of it by this calculation. Books, training programmes, certain coaches, and especially Apps can leave you with a mechanical expectation of a certain return for your investment. 

The overtraining syndrome definition

In the sports science and medicine literature, overtraining is a topic that has been discussed and described since the 1980s, but scientists still struggle to pin down an exact description and diagnosis of the condition, or what I’d prefer to call a ‘health imbalance’. If you view Table 1, you’ll see a few terms used in the overtraining literature, especially overreaching (of a functional or nonfunctional variety) and overtraining.

Adrenal fatigue

Adrenal fatigue is a notion I have been incredibly aware of from my nutritional therapy background when working with the general population. However, in the early 2000s, I suddenly thought it was the same as overtraining syndrome. I wrote a long paper entitled ‘Adrenal Stress as a Model of Overtraining’ in The Nutrition Practitioner in 2007 (3) and a shorter version in Functional Sports Nutrition magazine during its first year of publication in 2010 (4). I used the adrenal stress index test, which analyses salivary DHEA levels and the circadian rhythm of cortisol, as a benchmark for overtraining syndrome. This was a novel idea at the time because nobody else was writing about it – the sports scientists were talking in their language, and the functional medicine guys were speaking a different language.

Times have now changed. Sports scientists are starting to recognise adrenal fatigue as a real phenomenon. For example, Brooks and Carter from the Department of Kinesiology at Texas A&M University describe a direct link between stress and the adrenal glands and note that the physical stress of overtraining may cause the hormones produced in these glands to deplete (2).

In cases like my client Roger, adrenal fatigue is an extremely good model to work from. His cortisol levels were severely disrupted, with a clear reverse circadian rhythm, and his DHEA levels were theoretically that of a 90-year-old. At the time that I worked with him, Roger was a talented runner in his early 30s – his strength was that he hadn’t been racing since early in childhood like most athletes, so in my mind, he had (up until that time) decent physiological reserve.

Life load and overtraining syndrome

But, something I haven’t yet told you about Roger is that he was an investment banker, and you know how hard these guys work! If you do what most athletes do and view training as separate from the rest of their lives, he possibly under-trained compared to some of his rivals. However, many athletes would undertake much less demanding jobs, perhaps even part-time, to prioritise their running ambitions. So, in this regard, I would like to view the ‘3 P’s of Stress’ model by British psychoneuroimmunologist Dr Alex Concorde (5). An individual might not be physically pushing themselves too much in training, but within the overall life that they lead, psychologically and physiologically, they are adding to their total load, meaning eventual burnout in some manner or other.

Adrenal glands as a bank balance

I view the adrenal glands like a bank balance. If, for example, we have a daily account that starts with £100 in it, this should get you through most days quite comfortably. But, if we turn the currency into adrenal effort (i.e. stress of a physical or psychological nature), what will happen if, on most days, we’re withdrawing £20 but only depositing £18 (via good food, ‘me’ time and restorative sleep)? It won’t take very long before we only have £10 left in our bank account – when our balance is this low, it will only take one stressful meeting or one hard training session to push you into the red.

When dropping into the red, practitioners such as myself will receive emails complaining of being ‘man down’. My response to Roger’s concerns about his body was: “It takes a long time to get into an adrenal depletion, so unfortunately, it takes a long time to truly get out of it, and to stay out of it, you need to do things differently from before.”

Expanding our understanding of overtraining syndrome

Looking back, I was actually quite naive to think that overtraining syndrome could be explained simply by the model of adrenal fatigue. Examining the most recent overtraining literature, we have descriptions of blunted hypothalamus-pituitary-adrenal (HPA) hormone responses to stress tests (6,7); multiple proteomic changes (8); growth hormone and prolactin depletion (9); thyroid hormone alterations (10); depressed regulatory function of the autonomic nervous system (11); altered mitogen-activated protein kinases (MAPK) expression (12); negative impacts on immunity, energy metabolism and gut microbial diversity (13); downregulation of hepatic activating transcription factors (14); and even hepatic fat accumulation in mice (15).

Didn’t somebody say that exercise was good for us? From the perspective of getting the general population to move on a daily basis, the prevailing message should be just that. But, the message that should be coming through sports science and medicine literature more strongly is that we should be putting the reigns on some of our elite, semi-elite and highly motivated recreational athletes, especially the ones who have demanding jobs and a family to look after, like my client Roger.

Dr David Nieman (16) introduced the J-shaped curve concept in the exercise immunology literature. Through his own research, he observed that a sedentary population and heavily trained athletes were the individuals most likely to catch an upper respiratory tract infection, whereas moderately active individuals (at the lowest point of the J) had the most robust immune systems. In my mind, this model should be extrapolated across our entire physiology. As evidenced by the diversity of the aforementioned physiological balances associated with overtraining syndrome, we can now assume that doing too much is fundamentally damaging to our health – how that plays out in terms of symptoms will most likely relate to the individual constitution of the athlete in question.

Returning to the overtraining syndrome definition

As mentioned, scientists have been attempting to come up with a definitive definition (or diagnosis) of overtraining syndrome for a long time, but we are actually getting further away from that possibility. In the words of Kreher (1) and Carfagno and Hendrix (17), “The diagnosis of the overtraining syndrome is a complicated clinical endeavour. Therefore, much of the prevention of the overtraining syndrome is simply education of risk factors and ways to prevent excessive stress.” In terms of health interventions, they add, “Because the manifestation of the overtraining syndrome can vary greatly in individuals, treatment must be appropriate for the specific cluster of symptoms in each person.”

Additionally, according to Dr Elaine Lee (18) from the Department of Kinesiology at the University of Connecticut, in terms of tracking health, performance and recovery in athletes, we should be monitoring a comprehensive set of biomarkers, including:

• Nutrition and metabolic health
• Hydration status
• Muscle status
• Endurance performance
• Injury status and risk
• Inflammation
  
  

These are, in my mind, routine measurements that can be made by exercise professionals without having to make excessive use of sophisticated laboratory tests that might reveal some useful information in one overtrained athlete but miss a ‘diagnosis’ in another. If any of these bulleted items are under-par, the athlete is not performing at their best and needs a health intervention of some type. As a practitioner who likes to use a bit of technology (not too little and not too much), laboratory tests are really important, but we shouldn’t get too hung up on specific variables that may or may not be associated with the overtraining syndrome in the literature. After all, I haven’t found much mention of DHEA as a biomarker of overtraining, but when I’m faced with 90-year-old levels in a 30-year-old fit man, I will take action…

Conclusions

To close, I want to address a term I’ve noticed in the overtraining syndrome literature: ‘unexplained under-performance syndrome’. I will argue that all under-performance can be explained if you really want to look hard enough – I’ve yet to meet an under-performing athlete with whom I shake my head in confusion and send them back out the door. When a sports physician does a lab test for certain biomarkers, and none come back out of range, they might not see what’s wrong with their athlete. But when you just open your eyes and look, you can see it.

Ask the following questions: how hard is my athlete training; how much do they work; what are their stress levels; what is their exposure to environmental pollutants; does their food intake and quality match their physiological stresses; how much and how well do they sleep; what is their personal beliefs and cultures around hard work? You will then understand why they are under-performing. Our body is not a machine; therefore, it needs to be nurtured from a nutritional, lifestyle, movement and compassion point of view.