Overtraining syndrome and Non-functional overreaching: Practical application
When it comes to training, we often hear the term ‘overtraining’ used to describe an athlete pushing harder than usual and not seeing the returns in their performance. However this is often just overreaching or Non-functional overreaching (NFOR), whereas overtraining syndrome (OTS) is a medical condition which has a huge negative impact on an athletes life and career.
Non-functional over reaching describes a situation where an athlete is pushing themselves (overreaching) but their body is not adapting adequately to the training stimulus, therefore they are not gaining any functional outcome (e,g, aerobic capacity or strength) from their training. OTS on the other hand is a progression beyond this, more akin to chronic fatigue, which requires serious attention and can take months to years to fully recover from.
Diagnosing the training status of an athlete with regards to Non-Functional over-reaching or overtraining syndrome can be difficult. This is due to the lack of definitive markers for OTS and common symptoms between both states (Halson & Jeukendrup, 2004).
Physiological indications
When endurance athletes experience periods of over-training, the autonomic nervous system can become parasympathetic dominant in an attempt to restore homeostasis, as a response to the high level of stress during this period. This can lead to physiological symptoms such as; reduced heart-rate (HR) during exercise, reduced blood lactate (BLa) response due to reduced catecholamines, reduced ability to utilise glucose and feelings of fatigue and apathy (Lehmann et al., 1998).
Using some fictional 20km time trial with heart rate and blood lactate data for the sake of a visual, we can see how this might present in an athletes performance (figure 1 below).
Figure 1: Peak HR during 20km TT and BLa post TT
As can be seen, the athlete is unable to reach peak HR values that were previously achieved, indicating reduced HPA-axis responsiveness and parasympathetic dominance (Dejan, Jelica, & Dusica, 2013). The drop in lactate values may be observed as a positive change to a training programme, however in the presence of reduced performance and reduced ability to reach high HR levels, can be indicative of an over-trained state. Known as the ‘lactate paradox’ this can often be mis-interpreted (Bosquet, Léger, & Legros, 2001).
Stress/ recovery
There is a well established ‘dose-response’ relationship between training load and subjective recovery (Meeusen et al., 2012), which has been monitored in this instance using the REST-Q, which is shown to be responsive to changes in training load (Kellmann & Günther, 2000). Again using our fictional athlete we might expect a response similar to the below (figure 2).
Figure 2: Athlete’s REST-Q stress-Recovery scores
Whilst it is clear that the athlete is in a state of imbalance between stress and recovery, it is important to note that the two often occur over different timescales (Jürimäe, Mäestu, Purge, & Jürimäe, 2004), and without knowing where on the questionnaire scores are diminished, it is difficult to ascertain what is causing the drop. This aside, there is a clear drop in mood state and recovery, which coincides with the sudden increase in high-intensity training, followed by stagnation at a low score, indicative of NFOR or OTS.
On assessing the multiple performance and physiological markers presented, it is clear the athlete is either suffering from NFOR or quite likely OTS, however without knowing more information such as illness or disease state, which have to be taken into consideration as possible causes, it is not possible to use exclusion criteria (Meeusen et al., 2013) to confirm OTS.
Monitoring recommendation
Whilst there are currently no known markers which can be used to accurately identify OTS (Cardoos, 2015), there are multiple methods which can be used to help in the early detection of symptoms. The gold standard for detecting overtraining is a drop in sports performance, so this should be monitored closely to prevent onset of symptoms, however regular testing is not always practical and can be too late when trying to prevent OT (Urhausen & Kindermann, 2002). Since OTS can take months or years of rest to fully recover from and re-lapse is common (Morgan, Costill, Flynn, Raglin, & O’Connor, 1988), prevention is better than cure, and a more frequent test will help to achieve this.
Psychomotor speed testing
Nederhof et al., (2006) proposed that usable markers of overtraining should fulfil six criteria. They must be; objective, non-manipulable, applicable in training practice, not excessively demanding, affordable and based on sound theoretical framework. A promising method which satisfies all of these criteria is psychomotor speed testing. This is potentially a good indicator of overtraining, as athletes in this state often report decreases in cognitive processing speed, concentration and memory (Meehan, Bull, Wood, & James, 2004), supporting the hypothesis for a central mechanism leading to performance declines in overtrainined athletes (Lehmann, Baur, Netzer, & Gastmann, 1997). A large advantage of this type of testing over others is that they take little time and require minimal effort from the athlete. For example, a short computer based reaction test such as that used bySmith et al., (1999) in patients suffering from chronic fatigue syndrome (CFS) can be used, as there are well established similarities in symptoms between sufferers of OTS and CFS (Brooks & Carter, 2013). Another advantage of this type of testing is that analysis of data can be done quickly compared to other methods such as questionnaires and diaries, however these methods may provide more detailed insight into the athletes condition, which psychomotor testing alone would not provide (Meeusen et al., 2013).
An important consideration when using this type of monitoring, is that initial psychomotor performance and practiced psychomotor performance are predominantly limited by working memory limits and processing speed respectively, so a period of familiarisation should be used to establish sufficient practice that the athlete’s scores become stable (Chaiken, Kyllonen, & Tirre, 2000). Another factor which must be considering if psychomotor testing is to be used, is that research on this area is still in emergence and no set boundaries have yet been established to identify where along the training continuum an athlete is (Esther Nederhof, Lemmink, Visscher, Meeusen, & Mulder, 2006). With this in mind, it would be recommended that once familiarisation with the chosen test is complete, a period of testing should be carried out during a recovery phase, where ‘normal’ values can be established. From this, daily fluctuations can be established, and changes outside of this range noted, with training load being reduced in response where appropriate.
References
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