Overtraining
Making a Difficult Diagnosis and Implementing Targeted Treatment
Arja L.T. Uusitalo, MD, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 29 - NO.5 - MAY 2001
In Brief: Overtraining syndrome is a serious problem marked by decreased performance, increased fatigue, persistent muscle soreness, mood disturbances, and feeling 'burnt out' or 'stale.' The diagnosis of overtraining is usually complicated, there are no exact diagnostic criteria, and physicians must rule out other diseases before the diagnosis can be made. An orthostatic challenge shows promise as a diagnostic tool, but the subjective feelings of the patient remain one of the most reliable early warning signs. Prevention is still the best treatment, and certain subjective and objective parameters can be used by athletes and their trainers to prevent overtraining. Further studies are needed to find a reliable diagnostic test and determine if proposed aids to speed recovery will be effective.
Overtraining has for decades been one of the most popular topics in meetings and journals dealing with top-level sports. The problem has been well known for 70 years (1), but many specifics concerning overtraining are still very unclear. Researchers have tried to determine what happens to athletes when they begin to overtrain. How does the pathologic condition of the whole body progress? If the pathology and physiology of overtraining were better understood, we could have uniform criteria for the early recognition of impending overtraining and should be able to diagnose and cure the overtraining state with greater efficiency. Prevention is still the best cure, and athletes, coaches, and physicians need to recognize the early warning signs.
What Is Overtraining?
In medical literature, the word "overtraining" has had many meanings. It has been used to mean overload training, overreaching, and overtraining syndrome. Overload training, a few days of hard training followed by short-term fatigue, is an essential part of all athletes' training. The physiologic homeostasis of the body needs to be displaced by intensive training stimuli so that performance capacity can be improved, a process called reaching or supercompensation (2). Several days of intentionally heavy training are followed by some days of less intense training and rest to achieve supercompensation and peak performance.
The time needed for supercompensation is essential to recognize. If an athlete is not allowed to adapt before a new stimulus is given, a greater and progressive imbalance in homeostasis will occur (3). Reaching becomes overreaching when tapering the activity does not yield the desired supercompensation and fatigue is unintentional, resulting in performance decrement with or without other typical stress-related psychological, psychosomatic, and physiologic symptoms and signs. If the intensity and duration of the training are not reduced, overreaching leads to overtraining and overtraining syndrome, due mainly to long-term imbalance of physical training and recovery (figure 1). Overreaching differs from overtraining in its short recovery time. Recovery from overreaching can take 2 to 3 weeks, a safe time for tapering without a decrease in performance capacity (4). The recovery period in overtraining syndrome can take from many months to years.
![[Figure 1]](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_s_vlQlGd2x8E1Hzc4rlL8Js34lOUSfb00cLNf4Ni1_tBud51Vh7MBGORwrADGcupCIKSzPlUSBSN6lHuvqRaqfv77dttlyuoRaakuq957YG0Nrnv1MGJMErq_-f1YwkLVS4MDMYpV6=s0-d)
Overtraining state can be used as a synonym for overtraining syndrome. Overtraining state, also called athlete's maladaptation state, includes performance decrement with other typical stress-related psychological, psychosomatic, and physiologic symptoms and signs that can be graded from mild to severe. A mild form includes low-grade psychological and psychosomatic symptoms (eg, anger, fatigue, tension, loss of appetite, or sexual unwillingness), some short-term sleep problems, and muscle fatigue. It can also include immunologic or hormonal disturbances such as menstrual irregularities. A severe form includes symptoms such as depression, severe long-term insomnia, long-term muscle soreness, or some abnormal sense perceptions. It has been proposed that the duration of overloading time that resulted in the overtraining state is directly proportional to recovery time and also to prognosis (5).
Further Definitions
Two types of overtraining states have been presented (6,7): sympathetic and parasympathetic. The sympathetic type is possibly the impending overtraining state, proposed to be identical to acute stress reaction. Individual cases (7) show that the overtraining state seems to develop idiosyncratically due to different training histories and possibly heredity factors. In some cases, the "sympathetic overactivity" phase is missing from the pathophysiologic chain, or could not be detected. The phase slowly progresses to autonomic nervous system exhaustion when intrinsic sympathetic activity presumably decreases in connection with decreased responsiveness of the sympathetic nervous system.
The parasympathetic type can be defined as an advanced overtraining state or an exhaustion state. It could also be called "athlete's burnout." Parasympathetic activity has been proposed to increase with physical endurance-type training, as analyzed by heart rate variability measurements (8-10). Parasympathetic cardiac modulation tends to decrease (7) in all types of the overtraining state (7).
However, there is no real evidence for the aforementioned theories. We do not know in which situations an athlete will demonstrate the sympathetic or parasympathetic type of overtraining state and if these types really exist. Is the type dependent on training modality, training history, individual properties, sex, age, or something else?
According to von Israel (6), the sympathetic type appears mainly in sprinters and power athletes and the parasympathetic type in endurance athletes. It is also possible that young and less experienced athletes tend to react in a "sympathetic" way and experienced athletes in a "parasympathetic" way. We have found both sympathetic and parasympathetic types of overtraining states in endurance athletes (7). It is possible that athletes react individually to overloading and exhaustive training, no matter what kind of training they do. It remains unclear whether athletes reacting in a sympathetic way could develop an exhaustion type of overtraining state if training were continued. Stress researchers have reported that men and women react differently to physical and mental stress; men favor the sympathetic type (11,12). In my experience this seems to be ambiguously so.
The overtraining state has also been categorized as either peripheral or central (5). The peripheral type can mean local overloading, for example, at a muscle level. The central type, more complex and more severe, includes muscle soreness and fatigue due to changes in the central nervous system.
Overtraining research has been very unsystematic, and the terminology and study protocols have varied from study to study. The different overtraining terms make the analysis of literature more complicated. In many studies the various types have not been differentiated, making results difficult to interpret. Physiologic signs and symptoms can be opposite in so-called sympathetic and parasympathetic states, complicating efforts to set uniform criteria for the overtraining state.
Etiology of Overtraining
Factors that influence vulnerability to the overtraining state can be classified as internal and external (table 1). An athlete's stress tolerance is determined by his or her adaptation capacity, coping strategies, and physiologic properties. The total quantity of internal and external stressors determines how an athlete will react. Some athletes are more vulnerable to "burnout" or overtraining, which makes the role of coaches and the self-knowledge of athletes very important.
TABLE 1. Factors That Can Increase Vulnerability to the Overtraining State
Internal
General health
General nutrition
Mood state
Personality (type A) stressors
Hereditary physiologic factors
Age
Sex
Menstrual cycle External
Intensity of physical training
Volume of physical training
Social, economic, and psychological stressors
Training history
Environmental conditions and time of year
Food intake
Sleep (quality and quantity)
Infections
Medication, alcohol, tobacco, or other substances
Travel (jet lag, altitude)
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Of the internal factors, personality types A and B influence stress tolerance and coping strategies (13,14), but it is not known how personality influences the vulnerability to the overtraining state in athletes. As mentioned before, men and women seem to be different in coping with stress and possibly in stress tolerance. The incidence of overtraining is higher in men (15), but both sexes seem to respond to short-term overload training in similar ways (16). Personal experience during an experimental overtraining study shows that women were more vulnerable to the overtraining state.
Of the external factors, a progressive increase in intensive training volume with a considerable increase in total training volume is the strongest cause, inducing an imbalance between an athlete's adaptive capacity and the recovery time required. It is not known whether the main cause is the increase in intensity or the volume of exercise training. According to Lehmann et al (17), the worst two things are training monotony without recovery or easier training days, and an increase in training volume. In studies by my colleaques and I (7,8), both an increase in volume of intensive training and an increase in total training volume were needed to induce the overtraining state in endurance athletes. Koutedakis and Sharp (15) reported that the overtraining state appears mainly during precompetition or competition season when increased intensive training volumes occur.
It is obvious that traveling (jet lag) and strong environmental conditions (eg, altitude, cold, or hot weather) are additional stressors for an athlete's body, increasing vulnerability to the overtraining state. A deficient calorie intake seems to decrease stress tolerance (18), and sleep deprivation seems to affect metabolic and endocrine function (19).
Central Adaptation
There are many theories but not much evidence about the origin and the pathophysiologic changes of the overtraining state.
Possible central pathophysiologic changes are hypothalamic dysfunction (20); changes in concentration and function of neurotransmitters (amino acid imbalance theory) (21); changes in the hypothalamic-pituitary-adrenal (HPA) axis and pituitary function, and sensitivity to feedback from the periphery (22-25); decreased central command to skeletal muscles (26); and changes in autonomic nervous system function, which can have both central or peripheral context (7,27-29).
Hypothalamic dysfunction. The role of hypothalamic dysfunction in the pathophysiology, signs, and symptoms of overtraining is appealing; however, only a few studies cite it (20,22,23). Changes in noradrenergic, serotonergic, and/or dopaminergic activity in the brain (specifically in the hypothalamic and suprahypothalamic regions) can cause hypothalamic dysfunction, but the role of neurotransmitter changes in overtraining is unknown. It is assumed that chronic exercise training and stress may modulate the transmitter activity. The transmitters, especially norepinephrine and serotonin, also regulate pituitary hormone release during stress (30). Serotonin influences mood, sleep, temperature regulation, cardiovascular regulation, and higher brain functions.
Amino acid imbalance. An imbalance in amino acids could, in theory, lead to increased serotonin concentration in the brain. Prolonged and intensive exercise (21) and overloading exercise training periods (31) can increase tryptophan concentration and decrease the blood concentration of free branched-chain amino acids, leading to an increased concentration of brain tryptophan that is converted to serotonin. Some evidence has shown that chronic stress could also increase dopamine synthesis in the brain (30). On the other hand, animal studies have shown that reduction in central dopamine during exercise relates to increased fatigability (32).
Changes in the HPA axis. Sufficient evidence for the changes in HPA axis function and pituitary sensitivity in the overtraining state is missing. A very intensive training period during a normal training schedule seems to reduce maximal exercise-related concentration of adrenocorticotropic hormone (ACTH) and growth hormone and tends to decrease maximal exercise-related cortisol concentration (23). Conversely, resting ACTH concentration seems to be increased after exhaustive marathon races (33), a finding identical to the increased ACTH seen in exercise-trained rats and their response to acute stress (30). This phenomenon with "normal" cortisol concentration is the supposed result of decreased pituitary sensitivity to cortisol feedback and not decreased adrenal sensitivity to ACTH (25).
Autonomic nervous system dysfunction or imbalance has been presented as one reason for the signs and symptoms of the overtraining state (34). Intrinsic nighttime sympathetic activity has been proposed to decrease following intensive training and in the overtraining state as a compensating response to increased sympathetic activity during daytime activity and exercise training sessions (34). The increased low-frequency power of R-R-interval variability on electrocardiogram during supine rest in overloaded and overtrained athletes (34,35) refers to their possibly increased sympathetic activity at the cardiac level during daytime (7). Maximal exercise-related sympathetic activity was also found to increase during short, intensive training, as evidenced by increased catecholamine levels (28,29).
Related to the changes in sympathetic activity, physical training has been shown to change adrenoreceptor sensitivity and density (36). This influences plasma catecholamine levels via the feedback loop and responses to interventions such as exercise. These changes have not been demonstrated to progress during the overtraining state.
Peripheral Adaptation
The ability of peripheral organs to receive information from the central nervous system has been proposed to change in the overtraining state (17). Some changes take place with normal physical training, and this phenomenon is called peripheral adaptation. The question is where the limit between normal training and overtraining lies. For example, in overloaded recreational athletes, adrenal sensitivity to ACTH can decrease (37). This could explain some findings of decreased cortisol release in overtrained athletes (20,38,39) during exercise or hypoglycemia.
Peripheral changes related to overtraining could be changes in sensitivity and hormone secretion of peripheral endocrine glands (eg, decreased adrenal sensitivity to ACTH (32) and decreased secretion of thyroid hormones (40)). Peripheral changes might also include decreased glycogen stores (41), decreased neuromuscular excitability (42), changes in adrenoreceptor sensitivity (36), changes in immunologic function (43-46), and, theoretically, heart and skeletal muscle cell dystrophy.
Koutedakis et al (26) found decreased concentric maximal voluntary contractions in quadriceps muscle in presumably overtrained athletes. At the same time, they found no differences in eccentric maximal contractions between overtrained and normally trained endurance athletes. The authors attributed the discrepancy to impaired excitatory central drive to the spinal motoneurons in overtrained athletes. Six weeks of intensive cycle training decreased neuromuscular excitability (42), but recovery had already occurred in 2 weeks, even if the performance capacity remained decreased. Different recovery of peripheral and central mechanisms could explain this finding.
Diagnosis of Overtraining
Unlike with diagnoses of most diseases, physicians have no exact criteria for the overtraining state. The diagnosis is based on three points: (1) patient history, (2) carefully ruling out other diseases, and (3) laboratory findings.
History-taking includes a careful account of symptoms and signs (see table 1). Changes in training regimen are of utmost importance. Performance decrement with an increased feeling of fatigue (subjective and objective evaluation) is the main sign of overtraining.
The overtraining state can only be diagnosed after clinical examination has ruled out other conditions. Diseases such as Addison's disease, anemia and other nutritional deficiencies, asthma and allergies, cardiac diseases (eg, hypertrophic cardiomyopathy), diabetes or glucose intolerance, hypo- and hyperthyroidism, infections, muscle diseases, and psychiatric disorders can mimic overtraining.
Laboratory tests for differential diagnosis (table 2) and laboratory findings that can be connected to decreased performance capacity (table 3) (47-51) are helpful. Several laboratory parameters have been proposed to indicate an impending or actual overtraining state: a decrease in testosterone and increase in cortisol concentration, or a decrease in their ratio (52); decrease in nocturnal catecholamines (27); changes in catecholamine concentration in blood during rest and after exercise (53); decrease in maximal blood lactate concentration (53); decrease in plasma glutamine concentration (43,44); increase in uric acid and creatine kinase concentrations (reflecting overload at the muscle level) (53); decrease in the ratio of blood lactate concentration to ratings of perceived exertion (54); changes in morning heart rate (55); and changes in initial heart rate response to orthostatic stress (56).
TABLE 2. Laboratory Tests for the Differential Diagnosis of the Overtraining State
First Step
Hemoglobin, hematocrit, leukocyte count, thrombocyte count
Erythrocyte sedimentation rate
Blood glucose
Sodium, potassium, calcium
Alanine aminotransferase, alkaline phosphatase
Thyroxine, thyroid-stimulating hormone
Electrocardiograph (ECG)
Cardiac ultrasound
Clinical ergometric/ergospirometric test (ECG, blood pressure, PEF/FEV1 blood lactate, Borg scale) Second Step
Differential leukocyte count
Ferritin
Transferrin, albumin
Creatine kinase
Immunoglobulin (IgE)
Orthostatic test and autonomic nervous system function tests
Cortisol and testosterone (free testosterone) Third Step
Estrogen, follicle-stimulating hormone, luteinizing hormone
Adrenocorticotropic hormone (stimulation test)
Catecholamines (urine) and catecholamine metabolites
Magnesium, zinc Further specific examinations if needed
PEF/FEV1 = Peak expiratory flow/one-second forced expiratory volume
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TABLE 3. Recommended Parameters for Detecting Signs of Overtraining
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| Parameter in the Field | Sign of Impending Overtraining |
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| Subjective Psychological Evaluation |
| Subjective fatigue ratings | Increased feeling of fatigue despite adequate recovery time (easier training of 1 day to 2 wk) |
| Mood state | Decreased positive and increased negative feelings |
| Muscle fatigue ratings | Increased despite recovery time (easier training of 1 day to 2 wk) |
| Perceived exertion during constant exercise load | Increased |
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| Physical Performance Capacity |
| Heart rate during constant submaximal load | Increased |
| Time for a given distance with constant submaximal HR | Increased |
| Time for a given distance during maximal effort + HRmax, or | Increased; HRmax decreased |
| Time to exhaustion during constant velocity | Decreased |
| Power during maximal effort | Decreased |
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| Cardiovascular Factors |
| Resting morning heart rate | Increased or decreased more than normal individual variation |
| Heart rate response* to orthostatic test in connection with decreased heart rate variability during standing after standing up** | Increased or decreased more than normal individual variation |
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| Other |
| Weight and nutrition | Increased or decreased more than normal individual variation |
| Log of external and internal stress factors (other than exercise training) | See table 1 |
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| Parameter in the Laboratory | Sign of Impending Overtraining |
| Mechanical efficiency during submaximal load | Decreased |
| Maximal performance capacity (Wmax, VO2max, time to exhaustion***) | Stagnant or decreased |
| Nutrition and health status | See table 2 |
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| *Rest vs 3 min after standing—mean of a few heart beats, not the single value (66). **First standing minute excluded. ***Normal variation 2% to 12% in these parameters (74). HR = heart rate; HRmax = maximal heart rate; Wmax = maximal workload |
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There have been many proposals for tools that could be used to diagnose the overtraining state, but psychological symptoms and signs have been among the most sensitive indicators during very short to long-term training periods (16,57,58). Since the 1920s, psychological changes have been thought to be the main reason for the decrease in performance capacity of overtraining. Decreased positive feelings (eg, vigor) and increased negative feelings (eg, tension, depression, anger, fatigue, and confusion) normally appear, even after a few days, during an intensive training period. The most sensitive sign seems to be an increased self-perceived fatigue rating. Furthermore, increased ratings of perceived exertion during exercise after only 3 days of overloading could indicate a central limit of increasing fatigue (58).
Monitoring Training Effects
Athletes often visit their physician after they have suffered from overtraining symptoms for weeks. In that situation, the symptoms and signs can be attributed to overtraining or detraining or both. Many classic overtraining signs, such as those associated with autonomic nervous system function, cannot be detected after a 1-week recovery. Therefore, if possible, training effects should be regularly monitored by certain objective and subjective parameters. Many factors, most of which are reviewed by Tremblay et al (59),have to be controlled when evaluating the importance of changes in follow-up parameters (see table 4).
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TABLE 4. Factors That Should Be Controlled When Monitoring Intraindividual Training Effects by Measuring Physiologic Markers
Standardized Conditions
Time of day (47)
Time of year
Testing environment: humidity, temperature, light
Use of caffeine, alcohol, tobacco, or other substances
Nutrition and previous meal
Medication
Actual health
Menstrual cycle
Training history (48)
Training volume and intensity during previous days (49)
Time interval to previous exercise
Quality and quantity of sleep (50)
Stress level (psychological, social, economic) Methodologic Factors
Posture
Identical collection, transportation, storage, and analysis protocols Others
Changes in blood volume (51)
Changes in weight
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Training history and a sedentary lifestyle have been shown to influence hormonal changes induced by 1 week of intensive training (48). Some training/overtraining studies (22,37,42) have been performed using sedentary people as subjects, but they are not comparable to studies of athletes.
Changes in plasma volume have rarely been taken into consideration when the influences of training and exercise on blood markers have been measured, but the change in plasma volume is considerable during exercise and as a result of exercise training (51). It is one of the main reasons why heart rate, hemoglobin, and hematocrit changes induced by exercise training are detected after a very short period. Some hormonal changes induced by one exercise session, and possibly also by long-term exercise training, can be explained by a change in plasma volume (60).
Concerning some blood markers such as catecholamines, the acute stress of venous puncture increases the values derived from plasma or serum. After the venous puncture, resting for 30 minutes is recommended before blood sampling. If taken sooner, the values should be interpreted to reflect a degree of psychological stress and physical pain.
There are no overtraining studies in which all the aforementioned factors have been considered. The recommendations for follow-up parameters are presented according to the existing information. These markers can be indicators of an athlete's starting to move from adaptation to maladaptation. In that case, coaches and athletes should be careful to limit the dose of exercise training and other stressors.
Physical Parameters
Natural markers of the training state include changes in performance capacity (time to exhaustion, maximal oxygen uptake, maximal lactate, maximal heart rate) and physical performance-related parameters during submaximal exercise (blood lactate, oxygen uptake, heart rate). Which of these parameters first shows adaptation incompetence? Normally, efficient long-term physical training should improve all maximal and submaximal performance-related parameters. Highly trained athletes, however, require a lot of well-planned training to register some improvement.
In a study by Billat et al (29), endurance-trained male athletes showed some improvement of maximal performance (economy, running velocity) during a normal 4-week training period. Overloading did not immediately decrease performance capacity, and 4 weeks of further overload training did not change any maximal physical-performance-related parameters. Only submaximal heart rate, which already decreased after the normal training session, showed a further decrease (29). This can be partly attributed to increased blood volume and changes in intrinsic heart rate, but also to changes in autonomic nervous system function. Others have reported identical findings of unchanged performance capacity during short-term overloading with a decreased submaximal and/or maximal heart rate (58,59).
The most sensitive physical parameters for follow-up of the training state and overloading seem to be changes in physical efficiency, mechanics, and coordination (16,63) in addition to heart rate changes during submaximal and maximal exercise. Increased submaximal heart rate is a definitive marker of insufficient recovery during a continuing exercise training regimen (detraining excluded). However, results of submaximal exercise tests can be misleading (64). Low heart rate during submaximal exercise does not exclude the possibility of the overtraining state (65), and low blood lactate during submaximal exercise can be evidence of both increased performance capacity and low muscle glycogen concentration (64,66). Therefore, it is also important to measure maximal physical performance in conjunction with submaximal tests.
Secretory Indicators
Many hormonal changes appear first during exercise or some other intervention rather than during rest. Therefore, the most sensitive parameters of an impending overtraining state could be exercise-related hormone concentrations if monitored in follow-up (39). Hormonal changes have not proven to be sensitive or specific indicators of the overtraining state, but many neuroendocrinologic changes are naturally evident during the overtraining phase. Reliable measures of hormone levels during maximal exercise require appropriate laboratory conditions, which are not always possible. For results to be meaningful, identical collection, transportation, storage, and protocols of analysis must be observed.
Serum testosterone. Concentration of serum testosterone has been shown to directly reflect training volume and intensity but is not specific for the overtraining state (39,67-70). Testosterone concentration has been shown to decrease following endurance exercise training (70); however, decreased testosterone release does not appear to stem from functional changes at the testicular level but rather to changes in the function of the hypothalamus-pituitary-testis axis. Resistance exercise overtraining has not been studied as well, but testosterone concentration seems to increase with heavy training and overreaching in resistance-trained athletes (71).
Cortisol. The concentration of this stress-related hormone in serum can be postulated to change during the overtraining state. Findings concerning the changes of cortisol concentration during overtraining are controversial, reflecting different grades or types of overtraining state and individual differences in reaction types. Cortisol levels should decrease in hypothalamic dysfunction (20). Maximal exercise-induced cortisol rise has been reported to decrease with increasing training load and in the overtraining state (39). Saliva tests are preferred to serum tests if cortisol concentration is measured (25).
Catecholamine concentration. Findings of changes in catecholamine levels during overtraining are controversial. Increase in resting plasma norepinephrine concentration seems to reflect an increase in training load (39) and is not specific for the overtraining state. Intensive endurance training, however, seems to decrease exercise-induced catecholamine concentration (39,53). The behavior of stress hormone levels (maximal cortisol decrease and catecholamine increase) seems to be identical in overreached resistance- and endurance-trained athletes (28,71).
Plasma glutamine. Rowbottom et al (72) proposed an increase in plasma glutamine level to be a marker of long-term balanced training and a decrease in concentration to be an indication of overtraining (43,44). Glutamine is needed for optimal functioning of the immune system. Decreased muscle glutamine concentration, decreased secretory immunoglobulin (IgA) concentration (45), and changes in quality, quantity and function of white blood cells could be reasons for immunosuppression and susceptibility to upper respiratory infections in the overtraining state. However, Shephard and Shek (46) have concluded that immunologic parameters do not seem to be potential markers of the overtraining state in clinical practice.
Uric acid and creatine kinase. Plasma uric acid shows some correlation to anaerobic threshold, but creatine kinase concentrations, while they seem to react to acute overloading, are less reliable as potential indicators of overtraining (72).
Heart Rate
Measures of resting heart rate seem to be insensitive for the overtraining state, but a decreasing trend in heart rate variability during standing, in connection with a significantly increased or decreased heart rate response to standing up (orthostatic challenge), seems to indicate the impending overtraining state (7,65). Heart rate changes during an orthostatic challenge are recommended follow-up parameters of the overtraining state and may be a promising new diagnostic tool. Decreased heart rate variability during standing after standing up seems to be a change common to all types of stress reactions and overtraining states of athletes (7,65). Heart rate variability measurements, however, should be used carefully in individual follow-up because they are seldom reproducible (65) and require carefully standardized conditions. The ability to measure short-term heart rate variability during the challenge increases the sensitivity and specificity of the test for the impending overtraining state.
Contrary to this, heavy but tolerated training in a group of endurance athletes seemed to increase heart rate variability during standing, which strengthens the notion of heart rate variability as a promising diagnostic tool of the overtraining state (8).
Prevention and Treatment of Overtraining
Prevention is the best treatment for the overtraining state. Tapering the training regimen combined with rest, proper nutrition, and sleep help the body heal. Recognition and treatment of depression is important. Therapies such as massage and sauna baths can speed recovery.
Periodization of training with enough recovery should prevent overtraining (73) if other stressors and their influence on recovery are also taken into consideration (see table 1). Periodization means that correct loads of training stimuli are administered followed by adequate recovery periods. Periodization also diminishes the monotony of training when done over the short and long term.
Fifty-two training weeks of the year have been divided into phases of training emphasis called macrocycles. Each training week is called a microcycle (microcycles can be also longer—up to 10 days), and each microcycle includes both strenuous and recovery days in an appropriate proportion. Three or 4 microcycles compose a mezzocycle. Each mezzocycle consists of 2 to 3 microcycles with higher training loads and 1 recovery microcycle. Macrocycles with different training regimens can be classified as preparation, precompetition, competition, and tapering; all preparing for optimal performance in competition. As noted before, careful follow-up of athletes' subjective feelings and some objective parameters (table 4) are also an important part of prevention.
If the overtraining state persists in spite of all efforts to prevent it, effective treatment is needed. The best treatment is to rest and avoid sport activities for approximately 2 weeks. After the resting period, the patient can start light training. Athletes should try different sports, refraining from the training modality and intensity that caused the overtraining state. Training should progress very slowly, with the pace determined by carefully listening to the patient's feelings.
Athletes should forget the past and concentrate on the future. Otherwise, they can easily start comparing their performance and feelings to the time before the overtraining state, inducing a neurotic attempt to recapture the previous feeling. This can delay recovery and highlights the huge role of psychological factors in recovery. Professional psychological help is sometimes recommended for athletes who are seeking to overcome an overtraining problem.
Depression is one of the biggest psychological problems among overtrained athletes, and differentiation between primary depression and overtraining with secondary depression is difficult. Training history, discussions with coaches and other athletes, and a family history can help clarify this question.
Both primary and secondary depression need to be addressed with antidepressants and psychotherapy. Overtrained athletes, however, should get therapy for depression as soon as possible because it can speed recovery. This is only a hypothesis because there are no well-controlled studies about how antidepressant use affects recovery time. In secondary depression, the use of medication needs to be considered very carefully.
Adequate nutrition is one of the most important background factors behind a positive training effect and is also very important for overtrained athletes. If the diet is balanced, additional supplements and nutritional modifications have not been proven to speed recovery. The most common deficiency, especially in female endurance athletes, is iron. Zinc, magnesium, and calcium deficiencies have also been reported in endurance athletes, especially those who deliberately restrict their diets (75). In those cases, supplementation is needed.
The most commonly used supplements are the antioxidant vitamins C and E, but long-term, excessive intake of these vitamins can be harmful. Greater-than-recommended doses are not recommended even for overtrained athletes.
Amino acids are often used as supplements among athletes, but there is no consensus about their benefit. Research has not presented evidence for the benefit of valine, leucine, isoleucine, tryptophan, or glutamine supplementation among overtrained athletes (76). Future research is needed concerning this topic.
Adequate sleep is important during recovery. All additional stressors should be minimized. Traveling can increase tiredness, but in some cases, changing the environment and finding new hobbies can be good for recovery. Increased sexual activity may aid a recovering athlete, as it relaxes and modulates neurotransmitters beneficiently (77).
Massage, cryotherapy, and thermotherapy (including sauna bathing) are widely used to speed recovery. However, if an overtrained athlete feels exhausted and phlegmatic (parasympathetic type of overtraining), it is better to refrain from these therapies for several weeks. Powerful massage is also a type of exertion for muscles and may slow the recovery process. For phlegmatic athletes, caffeine can be used as a stimulant, but no evidence exists for its actual effects on recovery.
An All-Encompassing Approach
Unless tapering and adequate recovery time are built into a training schedule, overreaching can lead to overtraining. Objective markers for diagnosis of the overtraining state are few, but changes in heart rate variability during orthostatic challenge may be a promising new diagnostic tool. The subjective feelings of the athlete are still one of the most reliable indicators of an impending overtraining state. Until further studies reveal specific diagnostic indicators and confirm the efficacy of nutritional supplements, physical therapies, and psychotherapy as treatments, prevention is still the best cure.
