Overtraining: A State of Alarm

“Overtraining” is undoubtedly one of the terms that attracts the most attention among people involved in physical activity and sport. If exercise improves fitness and health, how can training make someone ill? This article addresses that question and others related to the term. Exercise that is not properly planned and structured can become a double-edged sword.

Training is a planned process that establishes loads and recovery so that controlled fatigue mechanisms occur and the intended physical adaptations can subsequently be achieved. The process can be summarized in 5 concepts: stimulus, fatigue, recovery, supercompensation and adaptation. The aim of exercise—the stimulus—is to create an imbalance in the body by disrupting “homeostasis” and subjecting it to “controlled” stress. This stimulus and the resulting physiological stress produce fatigue, whose magnitude depends on training intensity and the athlete's level. When we overcome this fatigue with appropriate recovery methods such as rest and nutrition, fitness rises above the initial level at which the training process began through supercompensation and adaptation.
Once the same stimulus has been repeated over time, it will no longer stress the body because adaptation has occurred—the general adaptation syndrome. We then need a greater stimulus than before by increasing volume and/or intensity and/or density so that the training process occurs again.

Using an analogy from medicine, physical exercise can be understood as a “medicine” that, when applied at the right dose, produces positive adaptation and raises fitness. Under the Schultz-Arndt law, if a stimulus does not exceed a certain minimum intensity, it produces no improvement or only a minimal one. But what happens at the other extreme if the exercise “dose” is excessive? What if the recovery period is insufficient for the exercise dose? This is the heart of the problem: a possible “training overdose”, known as chronic fatigue syndrome or overtraining syndrome (OTS).

With that understood, the definition of “overtraining” refers to an inappropriate balance among competition, training and recovery, resulting in reduced performance without an apparent pathological cause and caused by performance itself (Jidovtseff and Crielaard, 2001).

Classification of Overtraining

From a clinical perspective, OTS presents different degrees of severity. The recovery period will be longer or shorter accordingly.

• MILD OTS: This occurs after a short period of forced training sessions that exceed the athlete's tolerance, generally combined with repeated incomplete recovery. It causes mild OTS symptoms that do not significantly affect the athlete. After a few days of recovery, the athlete returns to normal and can continue training and competing without limitations.
• MODERATE OTS: This is a more advanced state of excessive training and inadequate recovery. The athlete presents characteristic symptoms of residual fatigue and requires a prolonged recovery period that may range from several weeks to several months. Medical supervision and monitoring of the relevant physiological and biochemical variables are needed to evaluate responses as objectively as possible.
• SEVERE OTS: Performance declines continuously, fatigue persists, and significant physical, physiological and biochemical changes occur, mainly neuroendocrine and immunological. Health visibly deteriorates and several organ systems are affected. Recovery requires very special attention. Hospitalization or admission to a recovery clinic is sometimes indicated to provide closer medical monitoring and personalized care. Recovery takes several months and may even exceed a year.
• CHRONIC OTS: In some cases, the condition is extremely severe and can even threaten the patient's life. It always requires hospitalization, intensive therapy or at least special care. The clinical picture is dramatic and may include acute renal failure, cardiac arrhythmias, liver damage and other problems. An aggressive, persistent treatment plan must be implemented.

Causes of Overtraining

Why does OTS occur? It is not caused by training one extra day; several factors can produce chronic fatigue. Some are listed below:

• Excessive High-Intensity Training
• Insufficient Recovery Between Stimuli or Training Sessions
• Excessive Training Volume
• Some athletes believe success lies in quantity and therefore do not allow the necessary recovery periods. They think victory can be achieved only through very hard, demanding training.
• “Training groups”: We all recognize the external motivation that comes from training with others. The risk is that group training often disregards the main training principle: individualization. A moderate pace for a higher-level athlete may be above another athlete's functional threshold, creating greater strain and training load. Two athletes who train together may therefore need different recovery periods after the same session.
• “Failure to respect load progression”: Athletes often return from injury or illness and try to “make up for lost time”. This commonly violates the principle of progressive training load and subjects the body to a stimulus for which it is not prepared.
• “Lack of training periodization”: This is especially common among recreational athletes beginning sports such as running or triathlon. Their training lacks logical organization, contains no load-deload cycle structure, and follows a monotonous program without periods in which the athlete can absorb the training load.

Prevention and Early Detection of Overtraining

Athletes tolerate different training levels. A stimulus that is excessive for one athlete may be too small for another and produce no physiological adaptation. Tolerance to training-induced fatigue also changes within the same season. It is therefore essential that athletes of every level follow an individual training plan that considers not only training factors such as volume, intensity and density, but also external factors that affect daily fatigue, including academic stress, personal relationships, family and work.

The following strategies are used to monitor training more closely:

• Among US swimmers, 10% showed overtraining symptoms. This percentage was reduced to 0 through POMS scales, a method for measuring mood states, by reducing training load when mood was low and increasing it when athletes' mood was higher (Budgett, 1994).
• An athlete's subjective perception of load—Subjective Load Equivalents, Cejuela and Esteve, 2011—first thing in the morning and after each training session, 20-30 minutes later, can be a simple, useful way to determine whether the training “dose” is correct. For example, high subjective-load values would make little sense during a deload week with relatively easy sessions and low volume and intensity.
• During competition there is no objective criterion for determining whether an athlete is overtrained. If performance is below expectations based on preceding training, however, we can assume that the taper was not appropriate and that the athlete arrived “overcooked”, as it is commonly described. Sufficient recovery is therefore essential both after competition, when an athlete gives 100%, and after high-intensity training, allowing the athlete to absorb the load and enter supercompensation.
• Use an objective method to quantify training load, such as TRIMPS or ECOs. This helps determine whether the athlete is completing the intended target load, or more or less than their level and condition can theoretically absorb.
• A more objective way to determine whether an athlete is absorbing the training load is to monitor biological parameters such as CK, urea and hemoglobin in blood tests.
• Finally, proper nutrition, hydration and rest between sessions help athletes absorb more training load and train better. Athletes who combine training with work or demanding academic lives do not recover in the same way as athletes who only train and rest. A recreational athlete should therefore never follow a program prescribed for a professional athlete.

Symptoms of Overtraining

How do we know when we are entering an OTS process? OTS symptoms can be highly individualized, which sometimes makes it difficult to tell whether an athlete's tiredness reflects the “normal” fatigue of training or the emerging disorder. Even so, certain symptoms occur in most cases.

The first indication of OTS is a decline in physical performance. The athlete may notice a loss of muscular strength, coordination and maximal-effort capacity.

OTS symptoms can appear at several levels, with differences between manifestations involving the sympathetic and parasympathetic nervous systems (García Manso JM, 1996).

At the sympathetic nervous-system level, symptoms are clearer and may allow rapid detection. They include increased resting heart rate, night sweats, appetite loss and the resulting reduction in body weight, emotional instability, increased basal metabolism, elevated resting blood pressure, delayed recovery, reduced peak lactate levels and/or increased incidence of infection.

At the parasympathetic nervous-system level, OTS symptoms are harder to identify because they are less alarming, and some can be confused with appropriate training adaptation. They include low resting heart rate and blood pressure, low heart rate during exercise, low plasma lactate during maximal and submaximal exercise—the lactate paradox—rapid pulse recovery, anemia, digestive problems, low reactivity and/or hypoglycemia.

Psychological Overtraining

In most cases, OTS is accompanied by psychological symptoms including depression, apathy, mood disturbances, hyperreactivity to stress, increased anxiety and perceived exertion, low self-esteem and difficulty concentrating (Fry, Morton and Keast, 1991).

Some authors use the term burnout to describe these symptoms of excessive demand, adopting the definition of Maslach and Jackson (1981): a three-dimensional syndrome characterized by emotional exhaustion, depersonalization and reduced personal accomplishment.

Although the name OTS appears to indicate that excessive training is the syndrome's only cause, stress from competition and exposure to non-sport stressors in an athlete's life also contribute. OTS incidence increases during both training periods and the competitive season, when physical effort is not generally greater but psychological pressure or stress is higher (Morgan et al., 1987).

Conclusions

• OTS is a disorder associated with an inappropriate relationship between training and recovery.
• OTS can occur at several degrees of severity, so the required recovery period may be longer or shorter.
• OTS has several possible causes, but it is primarily associated with excessive training load that the athlete cannot tolerate.
• RPE scales and training-load quantification are two valid tools that allow coaches to determine whether athletes are absorbing their training loads correctly and are not developing OTS.
• OTS symptoms affect athletes both physically and psychologically. Treatment involves stopping all physical activity for a relatively prolonged period.

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AUTHORS:

Sergio Sellés Pérez (Degree in Physical Activity and Sport Sciences. Lecturer and researcher at the University of Alicante).

Roberto Cejuela Anta (PhD in Physical Activity and Sport Sciences. Lecturer and researcher at the University of Alicante).