Over-training: A Brief Review

C. Harmon Brown

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Over-training is a complex syndrome difficult to diagnose, as it is the end result of a gradual progression from intensive training to short term over-training to the full-blown syndrome. There is considerable variation in each athlete's ability to adapt to a training regimen. When a group of athletes train together in the same program, many will adapt, while others will fail to do so and become over trained. Despite numerous studies in a wide variety of sports, no simple set of clinical or laboratory tests has been found which will readily separate the responses due to intensive training from those of over-training. However, if a laboratory is readily available, serial studies of the haemoglobin, white cell count, differential white cell count, and ferritin may be of some value. The coach and the athlete must be aware of those factors in the training program, such as persistent high loads, inadequate recovery, or sudden changes in the training volume/intensity which may precipitate over-training. the athlete and the coach must be able to communicate freely and discuss the athletes subjective responses to the training, as well as devising as many coping strategies as possible to reduce other life stresses. A training diary which records and assesses all of these elements in a systematic fashion would seem essential.

    Athletes and coaches live by the dictum that a progressive increase in the training load is critical to an improvement in performance. Gradual, progressive increases in the training volume and/or intensity are expected to result in a 'super-compensation' response, and better performance. When the expected competitive results fail to occur, the automatic reaction is that the athlete hasn't trained hard or long enough. This pattern on the part of the coach and athlete may well lead to 'Short term Over- training' (often called 'over-reaching'), or in the worst-case scenario, to 'Long term Over- training' characterised by a discernible extended period of poor results from further training.

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    In recent years a great deal of research effort has been directed toward a better understanding of the "Over-training Syndrome", especially its causes, diagnostic markers, management, and prevention. Vernacchia has recently provided a detailed review of the psychological aspects of over- training (3). Recent sports medicine publications and scientific gatherings are replete with numerous studies which focus on efforts to unravel the puzzling clinical and laboratory issues surrounding this problem (1.2.8). The "Over-training Syndrome" has been recognised for many years. It occurs in many different sports, and in animal species other than man. In today's sports environment of ever-increasing training loads, it may be difficult to distinguish between the temporary fatigue and aches and pains of a hard training session, and the gradual onset of an over-training syndrome. Furthermore, the signs, symptoms and pathogenesis of over-training will be different, depending on the event in question.

    Short term over-training (also called over- reaching) by definition, may last from a few days to two weeks. It is characterised by excessive fatigue after a work-out, increased effort during the training session (i.e., what used to be manageable is now a struggle), worsening of training performance, and a stagnation or decline in competitive performance. If a decrease in training load and adequate rest are permitted over the following 1-2 weeks, then recovery super-compensation and eventual improvements will occur. However, if the decision is to persist with the current training pattern, or there is an increase in the workload, then Long term Over-training is likely to develop.
    Over-training ("staleness", "burnout") is a SYNDROME i.e., a complex of symptoms and signs which may vary from athlete to athlete. The transition from post-workout tiredness to over-reaching to over-training may occur gradually, and it is difficult to distinguish one from the other, except in retrospect. Over-training is characterised above all by fatigue, both before, during, and after training; a deterioration in sub- maximal and maximal performance; longer rest periods are needed for recovery between exercise sets; muscles feel unusually sore and stiff, and the athlete feels the need for a massage. Psychological symptoms may predominate, with the athlete becoming moody, depressed, and irritable. Sleep patterns are disturbed and appetite and weight may decrease. In female athletes, alterations in the menstrual cycle are common, especially amenorrhea. The over- trained athlete also has an increased susceptibility to infections, especially viral upper respiratory illnesses. Over-training can be regarded as the body's reaction to a variety of STRESSORS, including those related to training, as well as others which are associated with the athlete's life-style.
    "High-risk" training and competition pat- terns may include:

  1. Repeated high-intensity training sessions, without adequate recovery. An increase in training volume is more likely to lead to over-training than an increase in intensity.

  2. Closely-spaced competitions, or a series of competitions, without sufficient recovery.

  3. Sudden increases in training load, without adequate time for adaptive conditioning.

  4. Monotony of the training routine.

    The addition of life-style or environmental stressors can add significantly to those of the training regimen, and must be considered when evaluating the athlete's overall conditioning status. These may include inadequate sleep due to work or study, academic pressures, financial worries, family and inter-personal conflicts, and travel demands ('jet lag').



    Many mechanisms have been proposed to explain the signs and symptoms of the over- training syndrome. Some of these have been well described in animal models, but they have been difficult to validate in human athletes.



  1. Depletion of muscle glycogen. This condition has been well described after repeat- ed bouts of endurance work, and it will lead to extreme fatigue and poor performance. Indeed, 'carbohydrate loading' has been used for many years to improve endurance performance and offset the effects of muscle glycogen depletion during training and competition. However, athletes who are suffering from over- training have not been restored to health by ingesting adequate dietary carbohydrate, nor has over-training been prevent- ed even though carbohydrate intake is adequate to meet the athlete's needs. However, attention to proper nutrition, with adequate total calories, nutrients, carbohydrates, and fluid replenishment is still critical to the athlete's health.

  2. Branched-chain amino acids (BCAA). The branched chain amino acids (valine, leucine and isoleucine) are utilised by exercising muscle, reducing their levels in the blood. In addition, plasma free tryptophan (fTRP) levels are increased. This combination allows more fTRP to enter the brain where it is converted to 5- hydroxytryptamine (5-HT), which interferes with a number of the brain neurotransmitters needed for a normal response to exercise. Maintaining higher blood levels of BCAA is theorised to block the entry of fTRP into the brain, and prevent the onset of 'central fatigue'. Although this has been demonstrated in animals, the evidence in man is conflicting and not well supported (4).

    Hence, despite strong commercial advertising and promotion, at present there is no good reason to advise the use of BCAA supplements as an energy source or over- training preventive.


    Many changes in the neuro-endocrine system have been described following intensive training as well as over-training. These include alterations in the hormones from the adrenal medulla and the adrenal cortex, such as the catecholamines (epinephrine and nor-epinephrine), and the 'stress hormone' cortisol. The hypothalmic - pituitary axis is also involved, with changes in prolactin and the gonadotropins - luteinizing hormone and follicle-stimulating hormone (LH and FSH). In females, suppressed non-cyclic levels of LH and FSH may lead to lower estrogen levels, menstrual cycle disturbances, and eventually the "Female Athlete Triad". Similar, but less apparent changes may occur in males, as both free and total testosterone levels have been noted to be suppressed in both sexes.


Diagnostic markers of over-training

1. Chemical Markers
    A number of the biochemical markers, as noted above, as well as the testosterone/cortisol (T/C) ratio and immune system alterations, have been touted as indicators of over-training. However, studies by other investigators have failed to differentiate the changes associated with intensive training from those of over-training with the use of these parameters. Furthermore, there may be considerable variation in response among individuals, so that unless good baseline values are established for each athlete, alterations are difficult to interpret. Hence, laboratory markers are expensive, low in predictive value, and not practical for the coach and athlete unless studies can be done frequently during the course of training.


2. Clinical Markers
    A number of clinical signs and symptoms have been espoused as 'early warning signs' of over-training. These include:

  1. Increase in the early morning heart rate. The heart rate must be taken when first awakening, and should be recorded each day. An increase of 5-6 beats per minute over base line suggests possible over- training, if other factors such as infection can be excluded.

  2. Weight loss and loss of appetite. A gradual loss of weight associated with a decrease of appetite is suspicious.

  3. Excessive fatigue, with failure to recover between training sessions.

  4. Sleep disturbances. The sleep pattern is disrupted, and the athlete still feels fatigued after a night's sleep.

  5. Muscle soreness. Persistent muscle soreness and stiffness, out of proportion to the training load, is often a tip-off. Athletes seek out the therapist, and request daily massage.

  6. Changes in mental status. Athletes (and/or their team-mates) note changes in mood, including depression, anxiety and irritability.

3. Psychological Markers
    Many studies now indicate that the athlete's subjective evaluation of his/her own mental and physical status is the best indicator of possible over-training. Thus, open communication between the athlete and the coach is essential for guiding the training program. A daily diary which records not only the actual training program, but also the athlete's perception of the intensity of the workload, would seem essential for the concerned athlete.
    Several workers have found that a questionnaire which assesses the athlete's feelings of well-being, mood and attitude correlates very well with more objective performance and laboratory indicators of intense training and possible over-training. Morgan's (5) Profile of Mood States (POMS) has been well validated in a number of studies of athletes in several sports in predicting over-training as well as eventual success. However, its 65-question format may be too tedious for frequent application.
    Hooper, et al (7) studied a group of Australian national swimmers for six months. They found that subjective ratings of sleep, fatigue, stress and muscle soreness on a scale of 1-7, with 1 = very low or good, and 7= very poor or bad could account for up to 76% of the variance in performance during training and competition. Foster (6), working with members of the US speed- skating team, has derived a formula for assessing 'training stress'. This involves the athlete's overall evaluation of the intensity of each day's workout (expressed as the rating of perceived exertion (RPE) on a modified Borg scale) x the duration of the work- out (minutes). The variation in daily training load (Le., standard deviation) for the week is used to determine the 'Monotony' of the workload. Weekly load x monotony = "Training Strain". Thus, when there is little variation in the daily training load, and hence little time for recovery, the monotony factor is magnified and "Strain" increases. Foster has shown that a high level of 'strain' correlates well with the incidence of respiratory infections, often a harbinger of over- training.


    A carefully designed training programme, with adequate time for rest and recovery, especially during periods of intense training, is essential in preventing over-training. Athletes need to 'listen to their bodies' care- fully, record their impressions in a daily training diary, and be able to communicate freely with the coach. The coach may need to take the lead, ask "how do you feel today?" and be willing to tailor the training programme appropriately.
    In addition, the coach and athlete must be sure that the athlete is receiving proper nutrition, with adequate calories to meet the demands of the workload and a balance of macro and micronutrients to maintain health. Given the time pressures of training, school and work, finding the time to prepare meals and to eat properly may suffer. In these situations, a post-training glucose- electrolyte replacement drink can be useful, as well as between-meal snacks. Vitamin and mineral supplements may be needed, but should not be a substitute for a balanced diet. Good hydration must be stressed as well. The athletes should monitor their weight to assure that their nutrition is adequate, and that they are re-hydrated after training.
    Adequate sleep is also essential for recovery from heavy training. The athlete should be refreshed from a night's sleep. Persistent lassitude may suggest an inadequate quality or amount of sleep, or may be a harbinger of over-training.


1. OVERTRAINING: The Challenge of Prevention, or a Consensus Statement American College of Sports Medicine/U.S. Olympic Committee Summit Orlando, Fla. June 7, 1998 . (available on Internet at Consensus statement).

2. FOSTER. C. and LEHMANN. M. CHAIRS: Training/Over-Training: The First Ulm Symposium Med. Sci. Sport Ex. 30 (7): 1137-1178,1998

3. VERNACCHIA, R.:Psychological perspectives on Overtraining. Track Coach 138:4393-4399;4420,1997

4. GASTMANN, UAL. and M.I. LEHMANN: Overtraining and the BCAA hypothesis Med. Sci. Sport Ex. 30(7): 1173-1178,1998

5. MORGAN, W.P. ET Al.: Psychological monitoring of overtraining and staleness Brit. J Sports Med. 21: 107-114,1987

6. FOSTER C.: Monitoring training in athletes with reference to overtraining syndrome Med. Sci. Sport Ex.30 (7) 1164-1168,1998

7. HOOPER, S.I., McKINNON, LT. ET Al.: Markers for monitoring overtraining and recovery Med. Sci. Sport Ex. 27 (1): 106-112,1995

8. BUDGETT, R: Fatigue and underperformance in athletes. Presented at American College of Sports Medicine annual meeting June 4,1998



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