Consistent with the general trend in modern life to push too hard, take on too much and try to be all things to all people, many athletes struggle to keep their training excesses in check.

In tackling endurance sports, the would-be athlete is usually armed with a rudimentary knowledge of periodisation applied with or without the guidance of a coach. The theory and practice of periodisation is a relatively mature application of Seyle’s General Adaptation Syndrome.

Han’s Selye was a physiologist interested in why humans age and die. He believed that accumulative stress was related to the aging process and based on this premise developed the “General Adaptation Syndrome” (GAS) in the late 1920′s and early 1930′s.

The GAS describes a person’s changing ability to adapt to stress through a lifetime. Briefly, Selye believed that humans exhibited a common response to most stressful situations regardless of their nature (i.e. physical, environmental, emotional). These responses include increased cortisol and catecholamine concentrations, and increase heart rate and blood pressure. The stimuli causing these responses were considered “stressors”. Various stressors are encountered from birth to death and each cases a stress response which includes various phases.

The first phase of the response is the alarm phase in which there is an initial disturbance in homeostasis. The second stage is the resistance phase in which adaptation is made and the organism is able to withstand the stressor. A third stage is also possible. If the stressor or accumulative stressors are so strong that resistance is not possible then the exhaustion phase is reached and illness or even death results.

Selye believed that the aging process could be partly explained by the result of accumulative stressors over a lifetime. The accumulation of stressors reduces the ability to resist stressors and will eventually result in an exhaustion stage resulting in death.

Although, it is presently known that GAS does not explain all responses and adaptations to stressors it can serve as a useful model to help explain responses and adaptations to exercise and training.

Although the increasing prevalence of Over Training Syndrome (OTS) has spawned a number of articles and research studies have discussed the problem of overtraining however there is still no universally accepted theory nor standardised diagnosis criteria for the syndrome. The main problem in formulating a general theory is the inconsistent responses of individuals classified as over trained.

All athletes apply the progressive overload principle to maximise their athletic abilities however there is a fine line between improvement and deterioration. When deterioration occurs in association with a heavy training schedule (volume and/or intensity) then this is referred to as overtraining, staleness or burnout. The main criteria for diagnosing overtraining is a reduction in performance, however other signs and symptoms associated with overtraining may occur prior to the decrease in performance and not all aspects of performance may be affected to the same degree. Diagnosing overtraining is therefore an inexact art and combinations of psychological as well as physiological measures are usually employed.

The major symptoms of overtraining are:

• Reduced performance
• Reduced enthusiasm for the sport
• Generalised fatigue
• Recovery prolonged
• Depression and or mood swings
• Joint and/or muscle pain
• Loss of appetite
• Changes in heart rate and blood pressure during rest, exercise and recovery
• Reduced iron count and mineral depletion
• Weight loss
• Insomnia
• Difficulty in concentrating
• Reduced self esteem
• Increased susceptibility to illness
• Delayed menarche for females
• Elevated cortisol and reduced testosterone levels

There are no universal criteria agreed on for overtraining and the symptoms listed above can vary from athlete to athlete.  It is important though to note these and keep an eye on their occurrence; drop the macho front and understand that as in most things in life less (training) is often more.

There are many theories on the cause of overtraining such as over stimulation of the hypothalamus and the autonomic nervous system, increased levels of the neurotransmitter serotonin, reduced muscle glycogen levels due to the inability of some athletes to consume sufficient calories during increases in training load. These theories explain some of the symptoms but at present there is a lack of an all-encompassing theory that explains all of the potential symptoms.

One of the more recent and plausible theories suggests that maladaption or lack of healing from high training volumes and/or intensities leads to local inflammation followed by chronic inflammation and finally a systemic or whole body immune response resulting in the majority of the symptoms of overtraining. This theory is known as the Cytokine Hypothesis named after the immune variables the cytokines. These entities co-ordinate the whole-body response to over training by: communicating with the central nervous system (CNS)and inducing a set of behaviours referred to as “sickness” behaviour, which involves mood and behaviour changes that support the resolution of systemic inflammation

So after all that theorising the best advice for prevention of overtraining is to allow sufficient recovery after hard training bouts along with adequate nutrition. A well-designed training program with regular periodised changes in training focus and recovery will go a long way towards prevention. Maintaining daily training logs and self-monitoring is perhaps the most practical advice for detecting and preventing overtraining. Careful self-monitoring of fatigue, aches and twinges, sleep irregularity, changes in appetite, especially cravings for sugar or caffeine, and resting and training heart rates.

Once an athlete is over trained the only course of action is rest or drastically reduced training. The factors that led to overtraining also need to be identified and eliminated. Complete recovery can take several weeks to several months depending on how long the athlete has been in the over trained state. This can seriously interfere with an athletes build up to an event or competition therefore perhaps it is better to be under rather than over trained?

Certainly, common sense would dictate that the aspiring endurance athlete pay as much attention and devote as much resource (time and money) to professional advice, preventative medical care (including massage, nutrition particularly for recovery) and achieving a balanced work and emotional state as they do to equipment.

I know of off road endurance folk who don’t think twice about spending thousands of dollars on a new bike or kayak but baulk at forking out $40 for a decent massage. The same people invariably look to friends for advice and don’t baseline their fitness through testing or call on the services of sports scientists, coaches and health practitioners to ensure they actually turn the training into racing!

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