Overtraining syndrome is a condition of maladapted physiology in the training stress syndrome, unexplained underperformance syndrome, muscle . the individual's current physiologic state in relation to recovery from prior work . tryptophan entry leads to increased serotonin, fatigue may decrease with. Exercise Performance Restraint Stress Central Fatigue Microdialysis Study Large Bailey S, Davis J, Ahlborn E () Effect of increased brain serotonergic activity on . In: Stanford S & Salmon P (eds) Stress, from synapse to syndrome. It is suggested that in overtrained athletes, central fatigue, mental exercise stress that elicits impairment of complex neuromodulation, also.
Its etiology has brought a great interest, mainly due to its multifactor feature, and it can be divided in two components: That division takes into account interactive metabolic factors affecting the muscles peripheral fatigue and the brain central fatigue upon the accomplishment of an intense physical work in athletes and other individuals 6.
In resistance sports, the overtraining syndrome is characterized by a persistent fatigue and apathy. Some researchers have been studying such fatigue, but its nature is yet to be clearly explained.
It can be muscular fatigue, and it may be related to the depression or even resulting from diseases. In general, the muscular fatigue involves a lack of ability in generating energy in a sufficient amount o maintain a given physical activity. The specific energetic path responsible by the muscular fatigue depends on the endurance and intensity of the event. It is possible that the energetic metabolism that is secondary to the endocrine changing is altered in the overtraining syndrome, and consequently affecting the fatigue as well.
Several diseases are associated to the fatigue, including anemia, mononucleosis, hypoglycemia, hypothyroidism, and the chronic fatigue syndrome Several case reports have demonstrated that the worsening in the sportive performance is associated to persisting viral infections for prolonged periods of time Whatever may be the cause of the fatigue in the overtraining syndrome, it is clear that there are more questions than definitive answers. The serotonin has an important role in investigating the development of the central fatigue, acting in the formation of the memory, in the lethargy, in the sleep and mood 33in the suppression of the appetiteand in the alterations of the strength perception Those training induced alterations in the metabolism of the nutrients have been proposed as one of the factors that contribute to the overtraining syndrome.
The "Central Fatigue Hypothesis" connects the signs and symptoms of the syndrome to similar symptoms than those that appear whenever there is an increasing concentration in the cerebral neurotransmitter serotonin It has been demonstrated that the cerebral serotonin level depends on the free in the plasma tryptophan that increases whenever the free fatty acid concentration increases. Due to the increase of the free fatty acid in the plasma levels during the resistance training, this theory proposes that the levels of cerebral serotonin increase before the presence of the overtraining 41, A similar alternative explanation admits that the ramified chain of aminoacids and tryptophan compete each other to reach the brain, and to penetrate into the hematoencephalic barrier.
According to this hypothesis, the decrease in the concentrations of the ramified chain aminoacids raises the level of the free tryptophan in the plasma and of the cerebral serotonin Up to this moment, the studies performed to determine the cerebral level of the tryptophan were made in animals. Those studies with rats present uniformity Data obtained from those studies support the above outlined hypothesis that the increase in the production of the serotonin in the brain, and its major metabolite 5-HIAA has direct relationship to the accomplishment of prolonged exercises 44,45 and to the appearance of the fatigue signs.
Both theories suggest that the cerebral serotonin increases up to the point that the fatigue and other overtraining syndrome's symptoms appear. This is not the only neurotransmitter associated to the perception and development of the fatigue, but it is the one that is under study However, the big existing discrepancy between experimental protocols makes it difficulty to analyze the results.
Even so, there are concrete evidences of the important role of the serotonin in the performance during prolonged exercises The overloaded training is related to the hard training for a few days, followed by a short recovery period that in this case is essential. The physiological homeostasis of the body needs to be stimulated through the intense training in order to imrove the sportive performance capability. This process is called super-compensation. Several days of intentionally heavy training are followed by a lighter training and resting for a few days, in order to reach the super-compensation and the performance climax.
It is essential that the necessary time to achieve the super-compensation is recognized. If an athlete is not yet adapted before a new stimulus is given, there will be a progressive and higher imbalance The result is the overreaching, that is a set of transitory symptoms, signs and changes that appear during the heavy training, and they are diagnosed through tests. Both the overreaching and the overtraining syndrome cause a decrease in the performance, as well as similar signs and symptoms, but they have different recovery time.
The overreaching needs two or three weeks to re-establish the sportive performance of the athlete, but in the overtraining syndrome, this process takes months or even years 7, The overtraining syndrome affects a considerable percentage of individuals involved in and resting intensive training programs.
It is defined as a neuroendocrine disorder hypothalamohypophysial that results from an imbalance between the demand of the exercise and the functional capability, and it may be aggravated by an inadequate recovery, thus causing a decrease in the sportive and athletic performance, the incidence of bruises, neuroendocrine changes, alterations in the mood, constant fatigue, among other symptoms 8.
Athletes of all performance levels may develop the syndrome, and a relevant number of signs and symptoms have been associated to it. But despite such extended list, up to this moment there are not yet quite established criteria 8maybe due to the lack of a culture implying in a systematic evaluation routine for sportsmen.
The malfunction or imbalance in the autonomous nervous system was presented as the reason for the signs and symptoms of the syndrome There are several but not well evidenced theories on the origin and pathophysiological alterations of the overtraining syndrome. There is also lack of sufficient evidence for the hypothalamohypophysial-adrenal axle HPA alterations, as well as for the alterations in the hypophysial sensitivity.
A quite intensive training period during a training program seems to reduce the adrenocorticotropic ACTH and the growth hormone 57 concentrations.
Peripheral alterations related to the overtraining syndrome can cause changing in the secretion of hormones and in the sensitivity of the peripheral endocrine glandules. These alterations also include a decreasing glycogen reserve, decreasing neuromuscular excitability, alteration in the adrenoreceptors sensitivity, and changing in the immunological function 7. The only effective treatment is the prolonged rest that makes impossible to the athletes to participate in competitions, and may lead to a loss of motivation, and even to abandon the sports.
Thus, the best way to avoid the syndrome to manifest is the prevention. Since up to this moment there are no physiological or biological markers that allow an early diagnosis of the syndrome 12the use of instruments that allow to find measurements to the mood 12 have demonstrated effectiveness in detecting the initial signs of the overtraining syndrome, preventing its complete development, and avoiding the inactivity period 58, It is considered highly susceptible individuals to develop the syndrome: The overtraining can be distinguished in basedovoid sympathicotonic and Addisonian parasympathicotonic.
The first one is characterized by the predominance of stimulation processes and an intense motor activity. The recovery after loads is insufficient and late. This form of overtraining is easy to be diagnosed, since the athlete feels sick, and there are several indicator signs and symptoms, such as: It is a prolonged response to the stress that precedes the exhaustion, and attacks younger athletes in anaerobic sports involving speed, strength and power.
Excessive amounts of training, anxiety and accumulation of competitions with insufficient recovering intervals are generally mentioned as factors that cause sympathicotonic overtraining. The anxiety of being obliged to produce maximal strength in the everyday train, and to compete in a great amount of events can be emotionally stressing, particularly in quite anxious athletes The parasympathicotonic originated syndrome is characterized by predominant inhibition processes, physical weakness, and lack of motor activity.
The athlete may express that he is not feeling tired, but he is not able to mobilize the necessary energy to participate in a sportive event. The resting athlete may present no symptoms, but these symptoms can supervene in a furtive and sudden way. It may appear depressive and neurohormonal manifestations, apathy and low resting heart rate This kind of syndrome affects highly trained athletes in aerobic sports, such as the triathlon, long distance swimming, marathon, and road cycling, and it is quite common in older individuals with a longer sportive life 5,6.
Several physiological alterations that occur in the overtraining syndrome have been described, but up to this moment, none of them was considered solely reliable to be accepted as a diagnostic test 63, Some of them are: The early diagnosis and prevention of the development of the whole situation, as well as to propitiate the maximum performance achievement demands in the full knowledge of the physiological and psychological processes involved in the physical adaptation before the stimulus he is submitted to.
External factors such as stress, interpersonal and environmental relationships have significant importance in this context, and important parameters must be considered in evaluating situations whenever the overtraining is observed. The overtraining syndrome is defined as a neuroendocrine disorder, in which the serotonin seems to have an important role in the physiology, along with other neurotransmitters.
But the study needs to be deepened together with nutritional aspects related to the tryptophan and the aminoacid levels of the ramified chain that can be involved in the central fatigue. The development of the overtraining syndrome involves several internal biological and external environmental factors that must be identified and controlled in order to avoid it is settled down.
Athletes, individuals involved in physical activities and rehabilitation, trainers, sports and health scientists would be benefited by the discovery of a simple, specific and sensitive test that allow to make the diagnosis of the syndrome.
On going studies are focused to validate instruments in the early detection of the overtraining syndrome in Brazilian athletes and non-athletes. American College of Sports Medicine. ACSM's Guidelines for exercise testing and prescription. Med Sci Sports Exer ; Noradrenergic versus serotonergic antidepressants: J Clin Psychiatry ;59 Suppl Int J Sports Med ;13 Suppl 1: Psychology of sport injury. Overtraining in endurance athletes: Med Sci Sports Exerc ; Making a difficult diagnosis and implementing targeted treatment.
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One must always consider a more pervasive medical cause for unexplained underperformance. It is very important that there is a frank conversation around the psychological aspects of dedicated endurance training. Many would contend OTS does not occur without some psychological stressor in the setting of excessive exercise.
In addition, athlete, coach, and sports medicine professional should be comfortable talking about mood and understand that depressed and anxious moods do not equate to mood disorders, but rather are symptoms of excessive exercise that may be adaptive or maladaptive. In addition, sleep disturbances can be a cause or effect of impaired mood, both of which can also be a cause or effect of overreaching. Conclusion OTS is a rare entity in the realm of overreaching in which 1 excessive exercise is not properly matched with recovery and 2 an excessive stressor leads to significant mood disruption in the setting of maladaptive physiology.
While many hypotheses exist as to the causative factors, research is still ongoing. Therefore, diagnosis remains clinical and often one of exclusion. Diagnosis of OTS can only be made after proper clinical evaluation and exclusion of the much more common medical conditions of endurance athletes.
Common conditions with presentations similar to OTS include asthma, anemia, hypothyroidism, immunodeficiency, hypocortisolemia, chronic fatigue syndrome, and depression among others. The hallmark of OTS prevention is education of the health care provider, athlete, and coach es. The most paramount warning sign athletes should be educated about is the caution one should employ when decreasing performances are meet with increased efforts without a return to better performance.
All stressors need to be shared among the team to avoid excessive training load.
- Diagnosis and prevention of overtraining syndrome: an opinion on education strategies
When possible, training plans and life stressors should be inversely matched. Standard tools anecdotally successful in OTS prevention include periodization of training and life stressors910 keeping a training log with RPE and adjusting volume and intensity based on performance, monotony, strain, and mood, 25 ensuring adequate calories, hydration, and sleep, 916 abstinence of training during periods of high stress in mood, sleep, environment, and body, 916 and utilization of a psychological monitoring through Recovery-Stress Questionnaire for Athletes, POMS, or Training Distress Scale.
Footnotes The author reports no conflicts of interest in this work. Mood states as an indication of staleness and recovery. Int J Sport Psychol. Koutedakis Y, Sharp NC. Seasonal variations of injury and overtraining in elite athletes.
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Diagnosis and prevention of overtraining syndrome: an opinion on education strategies
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