By Dr Dan Plews
Endurance athletes have to manage the stress generated through training with the recovery required to absorb that stress and turn it into positive adaptations. One of the major determinants of the outcome of a training intervention is how successfully stress and recovery are balanced; too little stress and too much recovery could lead to undertraining and the failure to realise potential; too much stress and too little recovery could lead to overtraining, excessive fatigue, and impaired performance. In this blog, we are going to focus on the latter – overtraining – what it is and how to avoid it.
The overtraining continuum
‘Overtraining’ is one of the many ubiquitous and inconsistently defined terms in endurance sport, much like ‘threshold’, and the misuse of the term creates confusion. Oftentimes, when athletes and coaches say that they are overtrained, they are really overreached. I like to refer back to a classic review paper by Shona Halson and Asker Jeukendrup from 2004 when explaining what overtraining is, and what its companion term, overreaching, is (2).
Halson and Jeukendrup defined overtraining (OT) as:
“An accumulation of training and/or non-training stress resulting in a long-term decrement in performance capacity…in which restoration may take several weeks or months.”
In contrast, they defined functional overreaching (FOR) as:
“An accumulation of training and/or non-training stress resulting in a long-term decrement in performance capacity…in which restoration may take several days to several weeks.”
Notice how the terms can be usefully differentiated based on their time course; overtraining is obviously a far more serious condition lasting several weeks to months, whereas becoming overreached is a much more short-term issue that could in many cases be relieved through tapering or a short de-load period. In fact, there may be instances within a programme when overreaching is desirable – functional overreaching at least – it’s part of the training process. Conversely, overtraining is always to be avoided. In my experience, when most athletes and coaches talk about “overtraining”, they’re really talking about overreaching. In my 20 years of experience as a coach and sports scientist working with athletes at the very highest level (and they like to push the envelope!), I have seen maybe two or three true instances of genuine overtraining.
As an athlete myself, I experienced true overtraining when I was training with Paul Amey in his build-up to the 2004 Olympics. We went on a training camp in Italy, and then I tried to continue the same training regime when I got back to the UK. It didn’t end well! I had a terrible finish to my triathlon season (DNF at nationals), constant upper-respiratory-tract infections, and an exceptionally suppressed heart rate. This indeed took me 3 months to recover from.
Anyway, back to the article by Halson and Jeukendrup. They went on to discuss their overtraining continuum, which describes the progression from the fatigue that may follow an individual session, to overreaching, and then to overtraining. The continuum shows that intensified training with inadequate recovery leads to increased fatigue and severity of fatigue symptoms, with overreaching progressing to overtraining if the process repeats over a sufficiently long timeframe. Other schools of thought are that the continuum is based on three distinct stages. These are overreaching, non-functional overreaching and overtraining (6). Non-functional overreaching exists between overreaching and overtraining and is less severe than overtraining but can still take several weeks to recover from (3). The term non-functional overreaching really means fatigue at an undesirable or unwanted time. For example, if you have a race and you’re more fatigued than you should be, this is non-functional overreaching.
This is a really useful model to use when discussing with athletes the need to balance stress and recovery to produce optimal outcomes.
Avoiding NFOR and Overtraining
NFOR is certainly more prevalent in athletes than OT; however, both are something we need to avoid. But how is this best done? Below are my five top tips on avoiding overtraining and managing fatigue, whilst still getting the most from your training programme. As always "you can't manage what you don't measure":
1. Look after your nutrition and maintain energy balance. Unless you are deliberately trying to lose weight, look to maintain energy balance as much as possible, and minimise periods of negative energy balance. This means consuming as many calories as you are expending, and avoiding spending days in a negative energy balance. A negative energy balance itself is a significant stress on our physiology, and adequate nutrition is required to ensure recovery and repair processes take place after a workout.
2. Don’t over-HIIT. High-intensity interval training (HIIT) is a powerful stimulus for generating positive adaptations to training (1). However, it is also very stressful and requires more recovery than low-to-moderate intensity training. Therefore, too much HIIT can put us on the road to overreaching and overtraining. This is one of the major rationale points behind polarised and pyramidal training intensity distributions, which call for ~80% of our training to be at low-to-moderate intensities (11). Therefore, whilst HIIT does indeed belong in an optimised endurance training programme, we need to ensure adequate spacing between HIIT sessions to avoid accumulating fatigue. A good rule of thumb is that HIIT should be followed by at least 48 hours of low-to-moderate intensity training below the first lactate threshold to ensure proper recovery (12).
3. Get enough sleep. It is hard to emphasise enough how important sleep is to the progression of an endurance athlete. Sleep is a critical part of the recovery process, and many athletes simply do not get enough. Athletes in serious training may require more sleep than the rest of the population – given the extra recovery processes required with serious training – and this may often be balanced against the need to get up early to train before work or other commitments. As athletes, we need to make sleep a priority! As hard as it might be, 8 hours per night should be a target.
4. Lower your training load when other stressors are high. Even non-athletes have stress; work, family, and so on can all take their toll on our physiologies. If non-training stressors are high, such as when preparing for a difficult exam or when under a lot of pressure at work, it is a good idea to dial back your training load to maintain the proper stress-recovery balance. Non-training stressors count!
5. Use HRV to manage your day-to-day stress-recovery balance. I am a big proponent of using daily, resting measures of heart rate variability (HRV) to help guide day-to-day training decisions (7–9). HRV, which can be measured reliably and with validity using a smartphone application (10), gives us insight into the functioning of our autonomic nervous system, and trends in our daily, resting HRV give us insight into the balance between stress and recovery; downward trends in HRV, or big daily fluctuations in HRV, tell us that stress and fatigue is accumulating. Therefore, by measuring HRV each morning, we can improve our daily training decisions to avoid becoming overtrained. In fact, HRV-guided training has been consistently shown to outperform pre-planned training in terms of adaptive responses (4, 5). We discuss how to use HRV to guide training in detail in our courses.
Use these tips, and the many others we share at EndureIQ, to avoid overtraining and ensure and/or your athletes avoid becoming overtrained, whilst still getting the most out of your programme to perform at your best on race day. EndureOn!
1. Buchheit M, Laursen PB. High-intensity interval training, solutions to the programming puzzle: Part I: Cardiopulmonary emphasis. Sports Med 43: 313–338, 2013. doi: 10.1007/s40279-013-0029-x.
2. Halson SL, Jeukendrup AE. Does overtraining exist? An analysis of overreaching and overtraining research. Sports Med 34: 967–981, 2004. doi: 10.2165/00007256-200434140-00003.
3. Israel S. Problems of overtraining from an internal medical and performance physiological standpoint. Med Sci Sports 16: 1–12, 1976.
4. Javaloyes A, Sarabia JM, Lamberts RP, Moya-Ramon M. Training prescription guided by heart-rate variability in cycling. Int J Sports Physiol Perform 14: 23–32, 2019. doi: 10.1123/ijspp.2018-0122.
5. Javaloyes A, Sarabia JM, Lamberts RP, Plews DJ, Moya-Ramon M. Training prescription guided by heart-rate variability vs. block periodization in well-trained cyclists. J Strength Cond Res 34: 1511–1518, 2020. doi: 10.1519/JSC.0000000000003337.
6. Meeusen R, Duclos M, Foster C, Fry A, Gleeson M, Nieman D, Raglin J, Rietjens G, Steinacker J, Urhausen A. Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the european college of sport science and the American College of Sports Medicine. Med Sci Sports Exerc 45: 186–205, 2013. doi: 10.1249/MSS.0b013e318279a10a.
7. Plews DJ, Laursen PB, Kilding AE, Buchheit M. Heart rate variability in elite triathletes, is variation in variability the key to effective training? A case comparison. Eur J Appl Physiol 112: 3729–3741, 2012.
8. Plews DJ, Laursen PB, Kilding AE, Buchheit M. Heart rate variability and training intensity distribution in elite rowers. Int J Sports Physiol Perform 9: 1026–1032, 2014. doi: 10.1123/ijspp.2013-0497.
9. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: Opening the door to effective monitoring. Sports Med 43: 773–781, 2013. doi: 10.1007/s40279-013-0071-8.
10. Plews DJ, Scott B, Altini M, Wood M, Kilding AE, Laursen PB. Comparison of heart-rate-variability recording with smartphone photoplethysmography, polar H7 chest strap, and electrocardiography. Int J Sports Physiol Perform 12: 1324–1328, 2017. doi: 10.1123/ijspp.2016-0668.
11. Seiler KS. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform 5: 276–291, 2010.
12. Stanley J, Peake JM, Buchheit M. Cardiac parasympathetic reactivation following exercise: Implications for training prescription. Sports Med 43: 1259–1277, 2013. doi: 10.1007/s40279-013-0083-4.
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