Overtraining syndrome (OTS)

March 22, 2017


Overtraining syndrome (OTS)

Natural Standard Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Related Terms

  • Adequate relative rest, amenorrhea, burnout, catabolic, chronic fatigue, cortisol, functional overreaching, hematologic profile, intensive training, nonfunctional OTS, overreaching, overreaching, overtraining syndrome, periodization, physiological adaptation, psychomotor, recuperation, staleness, stress, supercompensation, supplementation, tryptophan, underperformance.


  • General: Overtraining syndrome (OTS) is a detrimental physical state that occurs when the performance of an athlete deteriorates during periods of intense training or competition because the body does not have enough time to recover from intense exercise. It is sometimes called burnout, staleness, or chronic fatigue in athletes.

  • In severe cases, performance may worsen to below the starting level or OTS may prevent an athlete from competing or participating in the sport entirely.

  • As OTS provides no benefit to health or performance, it is not useful to athletes and coaches. Training programs can usually be structured in a manner that may prevent OTS.

  • OTS is highly relevant to athletes undergoing intensive training programs and is thought to affect 10-20% of elite endurance athletes. Athletes often compound the problem by increasing their training load in the mistaken belief that it will improve their performance.

  • Overreaching: OTS and overreaching are different but related terms, as long-term overreaching may lead to OTS. Overreaching is a deliberate intensive training technique used to improve athletic performance.

  • Athletes of any discipline, from endurance sports (such as running) to explosive sports (such as weight lifting), commonly use overreaching to improve athletic performance.

  • Overreaching programs are performed with the intention of causing a physiological adaptation called supercompensation, which is the body's attempt to adjust to increased physical demands by increasing muscular and aerobic capacity (fitness) above its starting level.

  • Short periods of underperformance, in which the athlete fails to meet fitness targets, are considered a normal part of overreaching.

  • Overreaching is classified as either functional or nonfunctional, depending on the outcome.

  • Overreaching that improves performance is described as functional overreaching and generally does not have long-term negative effects on the athlete. Benefits may occur when temporary underperformance or fatigue is followed by adequate rest and the body recovers within 24-48 hours. Including rest or lighter workload days in a training program is known as periodization.

  • If the athlete continues to underperform and feel fatigued after the rest period has elapsed, the athlete is said to have experienced nonfunctional overreaching (NFO). Continued NFO may result in OTS.

  • OTS and its cause: The precise mechanical, physical, and biochemical (pathophysiological) processes that result in OTS are not fully understood. The most common belief is that OTS is the result of elevated levels of stress hormones and decreased levels of androgens in the body. It is thought that these hormonal changes occur when the pituitary gland becomes overstimulated by excessive exercise. These hormonal changes may cause the body to enter a catabolic state where complex molecules are broken down into simple molecules, causing a loss of muscle tissue and impairment of the tissue repair needed for sustained and improved athletic performance.

  • History of OTS: Literature on the earliest identification of OTS is scarce, but the identification of OTS is commonly credited to Robert Tait McKenzie, MD, of Canada.

  • In his book Exercise in Education and Medicine, McKenzie, former director of physical education at the University of Pennsylvania, distinguished three physiological states following exercise. The first was momentary exhaustion with rapid recovery. The second was equivalent to what is now described as functional overreaching. The final state was staleness, or overtraining, and the body needed weeks or months to recover. He observed that athletes experiencing OTS had low blood pressure, weight loss, and large variances (more than 20 beats) between their standing and resting heart rates.

  • Some researchers have sought to redefine OTS as unexplained underperformance syndrome; however, most scientific literature continues to use the term OTS.


  • General: An athlete engaged in training loads that carry a risk of overtraining syndrome (OTS) usually requires a significantly higher consumption of calories than an athlete who is not training for both performance and recovery.

  • Deficits in the intake of nutrients become apparent more quickly due to the demands of the body for energy and tissue repair during strenuous training periods. If dietary intake is lacking, it may hasten the onset of OTS; however, OTS may still occur even when the body is receiving adequate nutrition.

  • Some evidence suggests that the athlete with OTS may have nutrient deficiencies, particularly in protein, healthy fats (monosaturated and polyunsaturated), and calcium.

  • Dietary considerations:

  • General: An athlete should maintain a dietary program in consultation with his or her trainer or nutritionist that is appropriate to his or her individual training program and nutritional needs. A diet consisting of 60-65% carbohydrates, 20-25% fats, and 15-20% protein is generally considered adequate to meet an athlete's needs; however, these ratios may be adjusted to suit the individual.

  • A diet, and possibly supplementation, that supplies as many of the body's nutritional needs for performance and recovery as possible may help protect against OTS.

  • Carbohydrates: Simple sugars (found in some fruits, vegetables, and processed and refined sugars) may be used to quickly replenish energy after training or competition. Complex carbohydrates (found in some breads, pasta, vegetables, potatoes, and grains) are derived from plants; contain calories, vitamins, minerals, and fiber; and take longer to digest. Extra carbohydrates are converted into glycogen and stored in the body for future use. There is some evidence that caffeine may increase glycogen synthesis.

  • Fats: Monounsaturated and polyunsaturated fats from plant sources (such as avocados and nuts) along with oils (like canola oil, olive oil, and safflower oil) help the body process vitamins and minerals.

  • Protein: Dietary protein, particularly from lean meats and dairy, is essential to repair damaged muscles from training.

  • Supplementation: Although some research suggests supplements may not offer protection against overtraining, other studies have suggested that supplementing with the amino acid glutamine may help reduce the occurrence of infections that often appear during periods of intense long-term exercise. Athletes who train intensely have been found to have lower-than-normal levels of glutamine in their blood, and it is possible that supplementation may redress this imbalance.

  • There have been studies with mixed results on the effectiveness of supplementing with vitamin C or the probiotic Lactobacillus fermentum in preventing the infections and illness that may accompany OTS.

  • Free radicals occur naturally in the body and may result in tissue damage. As exercise increases the presence of free radicals, some researchers suggest antioxidants such as beta-carotene, cherry juice, and vitamin E may reduce muscle damage, thus providing a buffer against OTS. Currently, there is little evidence to substantiate this theory.

  • Factors for an athlete to evaluate and discuss with his or her healthcare professional when considering supplementation include possible contraindications and interactions.

  • Diagnosing OTS:

  • General: It may be difficult to identify when an athlete has OTS. A qualified medical practitioner can obtain an accurate diagnosis and rule out other potential medical causes, such as asthma, an inflamed heart muscle, a viral infection, chronic fatigue syndrome (CFS), and major depressive disorder (MDD). However, no single decisive diagnostic test is currently available.

  • A commonly used measure for diagnosis of OTS is symptoms that continue after two weeks of adequate relative rest. What is adequate relative rest varies from athlete to athlete, reflecting both individual physical characteristics, such as recuperative ability, and the athlete's particular training program.

  • If the athlete continues to have symptoms after six months of adequate rest, this suggests that the problem may not attributable to OTS.

  • Symptoms: An early symptom of the onset of OTS is continued underperformance as measured against the athlete's previous performance history. The athlete or the trainer may observe this.

  • If underperformance continues, the training program, including its periods of rest, should be evaluated, along with the athlete's diet, general health, and mental state. It is important that the athlete is consuming sufficient carbohydrates, nutrients, and fluids to support training needs.

  • Other symptoms may include general fatigue, increased resting heart rate, decreased maximum heart rate, elevated blood pressure, increased susceptibility to minor infections, unnecessary continual muscle soreness, weight loss, decreased motivation, decreased appetite and competitive drive, loss of libido, difficulty sleeping, mood disturbances (such as depression, anxiety, and irritation), excessive perspiration, and not enough perspiration due to dehydration.

  • A comprehensive examination of the athlete and his or her individual training and lifestyle factors may show that a recent illness, such as a cold or the flu, may account for the underperformance and OTS symptoms. Other possible external causes, such as the demands of work, school, other physical activities, and emotional or psychological issues such as depression, should also be considered before a diagnosis of OTS.

  • In many cases, by the time a medical practitioner is consulted, the athlete may already have OTS.

  • Medical tests: Some studies have used laboratory testing, including obtaining a detailed hematologic profile (blood analysis), of athletes with OTS. Blood analyses may show elevated levels of stress hormones (cortisol and epinephrine) and decreased levels of androgens, commonly associated with OTS. For many athletes, such tests may be too costly, invasive, and time-consuming and may not provide a definite diagnosis. It may also be that by the time a medical practitioner has been contacted in response to symptoms, the athlete has already developed OTS. As a result, the daily systematic observation by the athlete or his or her trainer remains an important but relatively simple and cost-effective tool in identifying and preventing the onset of OTS.

  • A simpler alternative may be to measure the athlete's maximum oxygen consumption or maximum power output to see if it has been reduced, but as this could be caused by other factors (such as viruses or asthma), it may lack evidence for a diagnosis of OTS.

  • Other studies suggest the use of psychomotor speed (the speed at which routine physical and mental tasks are completed) testing as a diagnostic tool for OTS. This is because research suggests that athletes with OTS have similar symptoms to people who have CFS or MDD, including psychomotor slowness.

  • Daily monitoring: In addition to measuring performance, athletes engaged in strenuous training programs should be monitored using daily diary records of levels of fatigue and stress, perceived exertion, muscle soreness, and sleep quality. Measurements of body weight, body fat, blood pressure, heart rate, and food and fluid intake should also be taken. An assessment of the athlete's mental state may be accomplished by psychological testing such as Profile of Mood States (POMS) questioning to identify the athlete's mood.

  • One of the difficulties in diagnosing and treating OTS is that the same training program that causes one athlete to develop OTS may lead to improved performance in another. Furthermore, an individual's ability to adapt and benefit from a particular training program may also vary due to factors like the individual's base fitness and health, as well as external nontraining emotional or psychological stressors arising through employment, school, or interpersonal relationships. This illustrates the need to manage and monitor training programs on an individual basis.

  • Managing OTS:

  • General: Researchers suggest that the physical symptoms of OTS should be treated as first priority, as resolving these symptoms often resolves the associated psychological ones as well. Immediate short-term rest may be sufficient for mild cases, while others may require extended rest, monitoring of dietary and fluid intakes, and psychological support. A holistic approach to treatment may involve relaxation, counseling, psychotherapy, massage, hydrotherapy, close examination of nutrition, and the use of vitamins and supplements, in addition to rest.

  • Treatment of OTS is similar to that of CFS, and athletes usually recover quickly if their training is modified to address the central needs of rest and recuperation. It is important that the rest is adequate to allow for full recuperation; otherwise, the athlete may quickly relapse and underperform again.

  • The psychological symptoms of OTS may be more difficult to precisely treat, but the athlete's mental state may be measured using diary observations and psychological questionnaires. Treatment commonly includes taking time out from training (even in season), involving the athlete in decisions about his or her training program, and taking breaks from physical activity with mental activity such as technique and performance visualization.

  • In addition, psychological tools such as resilience training may help the athlete manage stresses involved with competition and competition preparation. The athlete may need increased reassurance and emotional support to deal with negative mood states arising from OTS and any frustration or anxiety at his or her inability to perform at the desired level.

  • Other studies suggest that managing the training load according to the mood of the athlete may help reduce the incidence of OTS.

  • OTS before competition: Additional difficulties may arise when increased rest is needed in the lead-up to a competition, causing preparation time to be reduced. Some researchers advocate maintaining the athlete's base fitness with a program that incorporates very light (so as not to affect the athlete's recovery) aerobic exercise or other activity that is not directly related to his or her individual sport. Other options are short sprints or power sessions that include substantially longer periods of rest than work. For severe cases requiring complete rest, neither of these options may be appropriate, and in all cases, medical advice should be obtained.

  • Following OTS in the lead-up to a competition, some athletes perceive their subsequent retraining to be faster and easier once they resume full training after the competition. It is unclear if this is a result of familiarity with the training or confidence in the outcome.


  • General: Excessive exercise is believed to overstimulate the pituitary gland and cause changes in hormonal levels. Athletes who have overtraining syndrome (OTS) have been found to have elevated levels of stress-related hormones (such as cortisol and epinephrine) along with decreased levels of androgens. However, the precise role of hormones in OTS has not yet been conclusively determined. These kinds of markers may be present in athletes who are experiencing functional overreaching rather than OTS. Athletes diagnosed with OTS do not always show these kinds of hormone fluctuations.

  • Analysis of the symptoms and blood analysis of athletes who have OTS has led many researchers to conclude that OTS may be the result of the athlete's body entering into a long-term catabolic state. A catabolic state occurs when complex molecules are broken down into simple molecules. When an athlete trains too much, blood tests sometimes show a rise in the by-products of protein metabolism (such as ammonia and urea). In addition, damaged cells release enzymes like creatine kinase. Blood levels of the stress hormones adrenaline and noradrenaline may rise as well. In the case of OTS, this causes a loss of muscle tissue and impairment of the tissue repair needed for sustained and improved athletic performance. In addition, a body that is stressed by training also metabolizes protein stored in muscles for energy, further reducing muscular performance.

  • OTS inhibits physical performance. The body's ability to fuel the muscles for work and repair tissue damaged by training is exceeded. If training stress on the body continues and the body remains in a catabolic state, performance may continue to deteriorate. Symptoms may remain until sufficient rest time is provided to allow the body to recuperate by repairing damaged muscle fibers and replenishing energy stores.

  • Any athlete thought to have OTS or be at risk of its onset should consult a qualified health care professional.

  • OTS risk factors: Certain types of training programs are thought to increase the risk of OTS. These include high-intensity interval training, in which repeated periods of strenuous activity are interspersed with shorter periods of rest. Other possible high-risk programs involve a sudden increase in the intensity of training, long periods of heavy repetitive training, and training conducted at times when the athlete is experiencing other nontraining stresses of a physical or psychological nature. The specific level of intensity, duration, and stress that triggers OTS varies among athletes.

  • In many instances, these kinds of training programs successfully improve athletic performance and are considered safe when the athlete is able to recover with less than two weeks of adequate relative rest. Studies suggest that athletes who engage in endurance training (such as distance running or swimming) may have an increased risk of OTS than athletes who participate in power or explosive training (such as weight lifting and sprinting). This may be because power or explosive training provides longer periods of rest relative to the duration of the exertion than endurance training. Competition periods may cause OTS, but it most commonly occurs during long-term periods of strenuous training.

  • Some research suggests that stressors originating from sources other than exercise may also play a part in OTS. Examples of these kinds of secondary stressors include stress originating from work or school or other emotional or psychological circumstances. Athletes who feel their training is monotonous, restrictive, or lacking in positive reinforcement may also have an increased risk of developing OTS.

  • Low-risk training: Some research favors training programs that allow the athlete recuperation sufficient to allow his or her body to fully recover at least every two weeks. Alternatively, the athlete may rotate between high- and low-load days to ensure adequate rest.

  • In general, training programs involving progressive increase in workload combined with a period where training load is tapered down are believed to carry a reduced risk of OTS compared to a moderate training program that continues year-round.


  • General: Researchers have identified several possible signs and symptoms in athletes with overtraining syndrome (OTS). Athletes frequently exhibit different combinations of signs and symptoms.

  • Diagnosis is further complicated because athletes who are experiencing functional overreaching (FO) often show some of the same symptoms as athletes who have OTS.

  • Fatigue: An athlete with OTS may experience persistent feelings of fatigue and excessive weariness, even after resting. This fatigue may cause underperformance accompanied by a reduction in the athlete's maximum level of physical effort and decreased maximum oxygen consumption. There may also be persistent muscular aches and soreness.

  • Changes in heart rate: Some athletes with OTS may have an increased resting heart rate and experience changes in blood pressure. An increase in resting heart rate of more than five beats a minute may suggest the athlete has OTS. In addition, the heart rate of an athlete who has OTS may be delayed in returning to normal levels after physical exertion.

  • Weight loss: There may be unexplained weight loss. In a trained athlete with already low body fat levels, even a small drop in weight may suggest the onset of OTS. During periods of significant physical stress, the body begins to metabolize protein stored in muscle tissue, which may decrease muscle mass and cause weight loss. An increase in metabolic rate or dehydration may also contribute to weight loss.

  • Sleep problems: The athlete may experience sleep disorders. This may present as difficulty sleeping, nightmares, or not feeling rested after sleep. Sleep is an important part of the body's recuperation, thus issues reducing the quantity and quality of sleep may compound the athlete's symptoms. Sleep disturbances may occur due to the muscles' increased uptake of amino acids during strenuous exercise. The increased utilization of amino acids may cause an imbalance in the levels of tryptophan, a neurotransmitter thought to be important to tiredness and sleep, which may lead to feelings of fatigue, lethargy, and depression.

  • Immune suppression: Long-term exercise may increase cortisol levels and reduce glutamine levels, which decreases immune function and may lead to increased incidence of infections, particularly of the respiratory tract. Other issues may involve allergies, asthma or flulike symptoms, and bowel disorders (such as diarrhea).

  • Overuse injuries: Injuries such as tendonitis, posterior tibialis syndrome, and stress fractures in the legs may occur in athletes with OTS. These types of overuse injuries are thought to be due to either the high-training loads or the body's inability to repair itself because of not enough recovery time between training sessions.

  • Menstrual irregularities: Researchers have also identified OTS as one cause of amenorrhea, the loss of the menstrual period in females that may cause a loss of bone density (osteopenia). Testing of the athlete's blood may also show increased levels of stress hormones such as cortisol and epinephrine and increased levels of creatine kinase, resulting from the microscopic damage sustained by the athlete's muscles during strenuous training.

  • Psychological changes: The athlete may experience negative mood states, such as depression, anxiety, tension, anger, and a loss of self-confidence. There may also be general irritability, an inability to concentrate, a lack of motivation, and apathy. OTS may also reduce libido due to a decrease in luteinizing hormone (which leads to low levels of testosterone in males and estrogen in females).

Author Information

  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).


Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Budgett R. Fatigue and underperformance in athletes: the overtraining syndrome. Br J Sports Med. 1998 Jun;32(2):107-110. View Abstract

  2. Budgett R, Newsholme E, Lehmann M, et al. Redefining the overtraining syndrome as the unexplained underperformance syndrome. Br J Sports Med. 2000 Feb;34(1):67-68. View Abstract

  3. Edwards AM, Clark N, Macfadyen AM. Lactate and ventilatory thresholds reflect the training status of professional soccer players where maximum aerobic power is unchanged. J Sports Sci Med. 2003; 2:23-29. www.jssm.org

  4. Hoch AZ, Stavrakos JE, Schimke JE. Prevalence of female athlete triad characteristics in a club triathlon team. Arch Phys Med Rehabil. 2007 May;88(5):681-682. View Abstract

  5. Johnson MB, Thiese SM. A review of overtraining syndrome-recognizing the signs and symptoms. J Athl Train. 1992;27(4):352-354.View Abstract

  6. Lehmann M, Gastmann U, Petersen KG, et al. Training-overtraining: performance, and hormone levels, after a defined increase in training volume versus intensity in experienced middle- and long- distance runners. Br J Sports Med. 1992 Dec;26(4):233-242. View Abstract

  7. McKenzie RT. Exercise in Education and Medicine. 2nd ed. Philadelphia, PA: W.B. Saunders Company; 1915.

  8. Morgan WP, Brown DR, Raglin JS, et al. Psychological monitoring of overtraining and staleness. Br J Sports Med. 1987 Sep;21(3):107-14. View Abstract

  9. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). www.niams.nih.gov

  10. Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com

  11. O'Connor PJ, Morgan WP, Raglin JS, et al. Mood state and salivary cortisol levels following overtraining in female swimmers. Pyschoneuroendocrinology. 1989;14(4):303-310. View Abstract

  12. Pedersen DJ, Lessard SJ, Coffey VG, et al. High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is congested with caffeine. J Appl Physiol. 2008 Jul;105(1):7-13. View Abstract

Copyright © 2013 Natural Standard (www.naturalstandard.com)

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.


March 22, 2017