What are overreaching and overtraining?
Overtraining is a phrase commonly used in competitive sport. True overtraining syndrome is actually quite rare, but the spectrum of conditions that come under the umbrella of unexplained underperformance syndrome can affect athletes more frequently. There are three main subsets of this syndrome.
The first is named functional overreaching. This occurs when an increased training load leads to temporary performance decrement, but following a period of rest or recovery there is an improvement in performance. For example, after a period of very intense training such as a training camp there will be a period of fatigue with a decrease in performance. Following an appropriate period of rest and recovery however, a super-compensation occurs, with athletes then displaying enhanced performance compared to baseline. Functional overreaching occurs over the short term – days to weeks – and is an important part of improving performance.
Non-functional overreaching occurs when periods of intense training are not followed by sufficient rest or recovery. This leads to a longer performance decrement, which is still reversible with full recovery after rest, but this takes longer and there is not the positive effect on performance due to accompanying symptoms and loss of training time. Symptoms include psychological effects such as fatigue or low motivation and/or hormonal disturbance. Non-functional overreaching symptoms and recovery last from weeks to months.
True overtraining syndrome is similar to non-functional overreaching but with a longer performance decrement (>2 months) and more severe symptoms (psychological, neurological, endocrine, immunological). Given that the only real measurable difference between non-functional overreaching and overtraining is the amount of time that it takes to recover, it makes it extremely difficult to differentiate or diagnose between the two at the time, and most diagnoses are made in retrospect.
Several confounding factors such as inadequate nutrition (energy and/or carbohydrate intake), illness, psychosocial stressors (work, team, coach, and family related), and sleep disorders may be present and can affect whether an athlete is able to recover effectively and work in the functional overreaching category, or if the training stress is too high for them at that time, pushing them into non-functional or overtraining.
The risk of developing overreaching or overtraining is dependent on the individual and will be different for different athletes, even with the same workload. This is further complicated by the fact that different athletes suffering from overtraining may exhibit a wide variety of clinical symptoms.
In a study of thirteen competitive swimmers who completed ten days of intensified training at the same volume and relative intensity, seven successfully completed the required training regimen. Three had difficulty completing the training requirements with significantly higher levels of mood disturbance, and the other three swimmers were so severely affected by the training that they had to be dropped from the study.
This demonstrates the importance of the coach-athlete relationship, and the need to adapt training to an individual athlete.
How do we diagnose them?
Overtraining syndrome symptoms include:
- Loss of motivation
- Lack of concentration
- Insomnia or waking feeling unrefreshed
- Agitation or restlessness
- Tachycardia or bradycardia
- Heavy, sore, stiff muscles
In association with a decrease in performance.
There is no specific diagnostic tool or test for overreaching or overtraining, and therefore it becomes a diagnosis of exclusion. The other causes of the symptoms and performance decline experienced by the athlete must be investigated and ruled out before overtraining can be diagnosed. These can include endocrine disorders such as hyper/hypothyroid; haematological disorders such as anaemia; infections; and psychological disorders such as eating disorders.
Another approach that is useful in identifying possible cases of overreaching or overtraining syndrome is to identify potential triggers in athletes.
- Increased training load without adequate recovery
- Negative energy balance (calorie intake less than calorie expenditure), depletion of muscle glycogen
- Monotony of training
- Excessive number of competitions
- Sleep disturbances
- Stressors including personal life (family, relationships) and occupational
- Other illnesses, e.g. respiratory tract infections
- Environmental factors (altitude, heat)
The European and American Colleges of Sports Medicine have a useful checklist to assist the diagnosis of overtraining syndrome.
How common are they?
The prevalence of non-functional overreaching or overtraining is difficult to assess. One study showed the lifetime incidence to be about 60% in elite runners, and 30% in non-elite. A recent longitudinal study of British age-group swimmers found 29% had developed non-functional overreaching or overtraining at least once in their career, with the risk increasing with higher skill levels. A previous episode of overreaching or overtraining puts an athlete at a higher risk of subsequent episodes.
(4, 5, 6)
The exact biochemical cause of overtraining syndrome is not well understood. It is thought that the triggers above lead to changes within the body, causing imbalances in a number of different systems and substances, including cytokines, neurotransmitters and hormones. There is no single test or substance that has been found to be reliably measurable to aid in diagnosis.
True overtraining syndrome – and even non-functional overreaching – is debilitating and it takes a substantial time for recovery to occur. Rest and very light training seem to be the only treatment available. Therefore it is extremely important to focus on the prevention of these conditions.
How can we prevent overtraining syndrome?
- Recognition of balance of training and recovery (appropriate periodisation)
- Find a good coach: individualised programming with adjusted volume and intensity to the athlete’s needs
- Avoid monotony in training
- Communication/self assessment/RPE/heart rate data etc.
- Nutrition (see more below)
- Sleep (see my previous post)
- Awareness of other life stressors
- Rest if signs of overreaching appear
- Adequate rest after illness/injury
- Referral to an appropriate physician if symptoms appear
What is the role of nutrition?
It is thought that the imbalance between training and recovery, which causes overtraining syndrome, may be associated with decreased muscle glycogen levels. Therefore adequate carbohydrate intake is essential in the prevention of overreaching or overtraining syndrome.
In a group of runners who ran 16 to 21 km daily for 7 days, performance dropped significantly when a moderate carbohydrate intake of 5.5g/kg body mass per day was maintained, with symptoms indicating that they were overreached. When the daily carbohydrate intake was increased to 8.5g/kg, the drops in performance were much smaller, and overreaching symptoms were reduced. Recovery from this week of hard training was more complete with the high carbohydrate treatment. (7)
A group of well-trained cyclists were required to perform 8 days of intensive endurance training. On one occasion, subjects consumed a 2% carbohydrate solution before, during, and after training (low carb), and on the other occasion, subjects consumed a 6.4% carbohydrate solution before and during training and a 20% carbohydrate solution after training (high carb). Total carbohydrate intake was 6.4g/kg body mass per day with low carb and 9.4g/kg with high carb. The intensified training protocol induced overreaching in both as indicated by a decrease in performance, but the decrease in performance was significantly less with high carb. Alteration of mood states and hormonal disturbances in response to exercise were also less on high carb compared with low carb.
Athletes in hard training seem to reduce (or not increase) their spontaneous food intake, and unless they supplement with carbohydrates, they may be in negative energy balance during periods of intensified training. It also appeared that the amount of carbohydrate ingested during training influenced the length of time needed for recovery. After 2 weeks of recovery from the intensified training, performance remained below that of baseline for the low carb treatment, whereas performance improved compared with baseline after 2 weeks of recovery from intensified training with the high carb condition. (8)
The change in carbohydrate intake alone appears to have had the ability to switch the cyclists from non-functional overreaching into functional overreaching with the associated performance gains.
Additional carbohydrates should not be at the expense of reduced protein intake as there is some evidence that insufficient protein can also result in an increased risk of overtraining. Dehydration and negative energy balance can increase the stress response, therefore also increasing the risk of overtraining.
The key takeaway points are that during periods of intense training such as training camps, high carbohydrate intake (8-9g/kg/day), adequate fluids and an even or positive energy balance should be prioritised.
Overreaching can play a useful part in improving athletic performance, but it is a fine balance to avoid non-functional overreaching or overtraining. The importance of the balance between training and recovery cannot be overstated. As a coach or an athlete, there are interventions that can be implemented to avoid this balance tipping the wrong way, including individualisation and periodisation of training, adequate sleep, targeted nutrition and understanding of the stressors outside of training.