ABC of Sports Medicine The overtraining syndromeBMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6952.465 (Published 13 August 1994) Cite this as: BMJ 1994;309:465
- R Budgett
Overtraining - hard training without adequate rest (pathological)
Over-reaching - hard training with adequate rest (normal)
Athletes may experience chronic fatigue for many reasons, but it often results from the stress of training and competition - when it is called the overtraining syndrome. The primary complaint is of reduced performance, which is objective and can be measured. Many athletes train at an elite level even to compete domestically, so fatigue due to the stress of training is not confined to Olympic athletes; 10% of college swimmers in the United States are described as “burning out” each year.
The cause of the overtraining syndrome is not known and there is no diagnostic or warning test. Intensive interval work (high intensity exercise with little rest) is most likely to precipitate the syndrome, so it is extremely rare in sprinters because they train with large amounts of rest. Sprinters may, however, suffer from postviral and other forms of chronic fatigue.
Overtraining is the process of excessive training that leads to the overtraining syndrome, which can be defined as a state of prolonged fatigue and underperformance caused by hard training and competition. There should be an objective measure of the loss of form, which will have lasted at least two weeks despite adequate rest and will have no identifiable medical cause. Symptoms of a minor infection, typically an upper respiratory tract infection, may recur each time the athlete returns to training after inadequate rest.
Over-reaching is the process of hard training that enables athletes to reach their full potential. It is part of a planned programme to stimulate adaptation and, when combined with periods of rest, permits the normal physiological response of full supercompensation. This contrasts with the pathological response to training in the overtraining syndrome.
Precipitating factors of the overtraining syndrome
Training - Intensive interval training - Sudden increases - Large volumes of monotonous training
Stress of competition and selection
Physical stresses - Glycogen depletion - Dehydration - Other illness or injury - Psychological stress of life events (for example, moving house, exams, relationship problems)
Symptoms of overtraining* Underperformance
Depression (loss of purpose, competitive drive, and libido)
Loss of appetite, and weight
Increased anxiety and irritability
Sleep disturbance (in over 90% of cases) - difficulty getting to sleep, waking in the night, nightmares, and waking unrefreshed
Frequent minor infections, particularly of the upper respiratory tract
Raised resting pulse rate
Signs of over-reaching (which is normal if athletes recover quickly)
High serum creatine kinase concentration
Low ratio of serum testosterone to cortisol concentrations
Falls in muscle glycogen concentration
Raised resting heart rate
Athletes present with fatigue, heavy muscles, underperformance, and depression. Direct questioning reveals poor sleep in over 90% with difficulty getting to sleep, nightmares, waking in the night, and waking unrefreshed, which may be important in the pathogenesis. Other symptoms are loss of purpose, energy, competitive drive, and libido; emotional lability; increased anxiety and irritability; loss of appetite with weight loss; excessive sweating; and a raised resting pulse rate. Some athletes keep catching minor infections every time they build up their training.
The history usually involves an increase or change in training.
Intensive interval work - Many athletes break down when they switch from low intensity winter training to high intensity summer training with intensive interval work. The stress of competition and selection pressures may also contribute. The athletes can usually keep up at the beginning of a race but describe an inability to lift the pace or sprint for the line.
Fast athletes - Some athletes are going faster than ever before but think that training even harder is the only way to achieve even greater success, so they cut recovery time to permit more training and competition. One swimmer broke the British record and then decided to cut his rest day to train seven days a week instead of six. He broke down after several months and took many weeks to recover. Another swimmer increased his training to eight hours a day; for four months his performance improved, but then he started to fail to recover from training and took months to recover form.
Slow athletes - Other are trying to keep up with peers who are faster, so the stress of training is greater and they become fatigued. It is difficult for them to accept the diagnosis because they are training less than other competitors, but it is their individual response to training that matters.
Sudden increase - Some suddenly increase their training in order to catch up after a break due to illness or injury when it would be sensible to increase training gradually. They get more desperate and train harder as they fall further behind.
No periodisation of training - Occasionally training may be heavy, monotonous, and without periodisation (cyclical variation of training).
Stresses such as exams and other life events, glycogen depletion, and dehydration will reduce the ability to recover from, or respond to, heavy training. However, it is rare for athletes to break down after less than two weeks of hard training (as in a typical training camp) provided that they then rest and allow themselves to recover afterwards.
These are inconsistent and generally unhelpful in making the diagnosis. They include increased postural drop in blood pressure and postural rise in heart rate, slow return of the pulse to normal after exercise, decreased lactic acid levels during exercise, reduced maximum oxygen uptake and maximal power output, and increased submaximal oxygen consumption and pulse rate. Investigation
Exclusion of other causes of chronic fatigue
History - inquire about infection, wheeze, eating disorders, chest pain, and shortness of breath on exercise
Examination - to exclude a medical cause
Investigation - depends on clinical possibilities. May include lung function and laboratory tests
Overtraining may cause immunosuppression by:
Raised serum cortisol concentrations
Low serum glutamine concentrations
Low salivary IgA concentrations
Laboratory tests rarely help in the diagnosis of chronic fatigue
Prevention and early detection
Early detection of overtraining syndrome is difficult
Monitor: Performance Mood state Resting heart rate
It is often difficult to persuade athletes and coaches that overtraining has caused underperformance. Investigations are needed to exclude other causes of chronic fatigue and to convince an athlete that there is no undiagnosed illness. The range of these tests depends on a sensible approach to clinical possibilities. Serious disease such as viral myocarditis and arryhthmia is rare but must be excluded if suspected. Prolonged glycogen depletion, as in anorexia nervosa, may cause chronic fatigue in its own right. A history of recurrent upper respiratory tract infections may represent allergic rhinitis or exercise induced asthma, in which case lung function tests are needed.
Laboratory tests are occasionally helpful but their use in diagnosing and monitoring chronic fatigue in athletes has been overrated.
Haemoglobin concentrations and packed cell volume decrease as a normal response to heavy training. An athlete's reported anaemia is often physiological, due to haemodilution, and does not affect performance. Increasing the haemoglobin by altitude training or blood doping (cheating), however, does seem to improve performance.
Ferritin - It is controversial whether low serum ferritin concentrations (which reflect low iron stores) can cause fatigue in the absence of anaemia. If the ferritin concentration is very low, however, treating an athlete with iron by mouth is reasonable.
Creatine kinase - There is a wide individual variation (50-fold) in the response to hard exercise. Serum concentrations above 2000 mmol/l have been seen in normal marathon runners and do not indicate who will break down with chronic fatigue.
Viruses - Viral titres must be shown to rise, and the history is normally suggestive of a post-viral illness. The Paul-Bunnell test is diagnostic and there may be high serum levels of enteroviral particles.
Trace elements and vitamins - There is no proved link of vitamin or trace elements to the overtraining syndrome, and the widespread use of supplements by athletes does not seem to offer any protection from chronic fatigue.
Athletes can tolerate different levels of training and competition stress; overtraining for one may be insufficient training for another. Each athlete's tolerance level will also change through the season so training must be individualised and varied and should be reduced at times of other stresses such as exams. Unfortunately athletes are exhausted most of the time unless they are tapering for a competition, so it is difficult for them to differentiate overtraining from over -reaching. Investigators have tried to identify strategies for early detection.
In American college swimmers a 10% incidence of burnout was reduced to zero by daily mood monitoring with a profile of mood state (POMS) questionnaire, and by reducing training when mood deteriorated and increasing it when mood improved.
A persistent rise in early morning heart rate despite rest is non-specific specific but does provide objective evidence that something is wrong. Underperformance is usually noticed too late and serial measurements of blood concentrations of haemoglobin and creatine kinase and of packed cell volume do not help. Good diet, full hydration, and rest between training sessions will help athletes tolerate hard training. Those with a full time job and other commitments will not recover as quickly as those who can relax after training. There are no objective tests to predict which athletes are going to break down during a period of hard training so adequate time has to be allowed for all of them to recover. Periodisation of training should permit this, with particular care at times of intensive interval training and hard monotonous training.
Management of the overtraining syndrome
Relaxation strategies and rest, with regular very light exercise
Communication with the coach
Strong reassurance that the prognosis is good
Overtrained athletes v patients with chronic fatigue
Their primary presenting complaint is of underperformance, which is an objective measure of their condition
They present earlier, are less severely affected, and recover more quickly
The main stresses in their lives are exercise and competition, which can be controlled
The main problem in rehabilitation is in holding them back, rather than having to encourage appropriate exercise
The treatment of any chronic fatigue syndrome requires a holistic approach, and athletes are no exception. Rest and regeneration strategies are central to recovery. Five weeks of rest appreciably improve both performance and mood state, and there is growing evidence that a very low level of exercise will speed recovery. Thus athletes must exercise aerobically (but not so hard that they cannot talk) for a few minutes each day and slowly build this up over many weeks. The level will depend on the clinical picture and rate of improvement, and recovery generally takes 6-12 weeks. Many make the mistake of trying to do a normal training session, suffering from severe fatigue for several days before partially recovering, and then doing it again. Cross training (playing another sport) may be the only way of avoiding the tendency to increase the intensity too fast.
Regeneration strategies are widely used in the old Eastern bloc countries, although there are no controlled trials of treatment. They consist of rest and relaxation with counselling and psychotherapy. Massage and hydrotherapy are used, and nutrition is looked at in detail. Large quantities of vitamins and supplements are given, although there is no evidence of their effectiveness. Any stresses outside sport are reduced as far as possible.
There is one report of the use of anabolic steroids (which are banned in athletes) in an attempt to speed recovery, but drugs are not generally of value unless depression is a major factor.
Athletes are often surprised at the performance they can produce after 12 weeks of extremely light exercise, and it is then that care must be taken not to increase training too fast. They need to train hard to go faster, but they must rest and recover completely at least once a week to benefit from all their hard work.
Richard Budgett is medical director of the British Olympic Association and medical officer at the British Olympic Medical Centre, Northwick Park Hospital, Harrow, Middlesex.
The ABC of Sports Medicine has been edited by Greg McLatchie, visiting professor of sports medicine and surgical sciences at the University of Sunderland, consultant surgeon at Hartlepool General Hospital, and director of the National Sports Medicine Institute, London. This paper has been edited in conjunction with Clyde Williams, professor of sport science at the University of Loughborough.