Overtraining is one of the most discussed and at the same time least understood conditions in sports medicine. It is easy to attribute any drop in results to it, but true overtraining syndrome occurs more rarely and lasts considerably longer than ordinary fatigue. The editorial team examined where it comes from, how it relates to training load and why pharmacology here often only makes the situation worse.
Overreaching and overtraining: terminology
The joint consensus of the European College of Sport Science and the American College of Sports Medicine proposes viewing overtraining as the end point of a continuum (Meeusen et al., 2013). At the beginning stands functional overreaching (functional overreaching) — a short-term, planned decline in performance after a hard block, followed by supercompensation.
If load continues without sufficient recovery, non-functional overreaching develops. Performance drops for weeks or months, psychological and hormonal symptoms appear, but full recovery is still possible without a lengthy break in one's career.
Overtraining syndrome is the most severe form: the decline in results lasts for months, and to it are added sleep and mood disorders, frequent infections, appetite disturbances. Distinguishing non-functional overreaching from overtraining syndrome is often possible only retrospectively — by how much time recovery took.
Scientists acknowledge that true overtraining syndrome has been poorly studied: it cannot be ethically reproduced in an experiment, and most data come from case reports and observations (Halson & Jeukendrup, 2004).
| State | Decline in results | Approximate recovery time |
|---|---|---|
| Functional overreaching | Short-term, with subsequent gains | Days — up to 2 weeks |
| Non-functional overreaching | Prolonged, without supercompensation | Weeks — months |
| Overtraining syndrome | Prolonged, with systemic symptoms | Months |
Load mistakes that lead to overtraining
The classic cause is a prolonged mismatch between load and recovery. However, the consensus emphasises that the matter is not only "too much training": cumulative stress matters, which also includes sleep deprivation, work, study, travel and emotional tension (Meeusen et al., 2013).
A typical mistake is increasing volume and intensity at the same time. Also considered risky are monotonous programmes without easy days, frequent competitions without recovery periods and sharp "catching up" after illness or injury.
The psychology of "more is better" is also dangerous. When results decline, a motivated athlete often responds with extra training instead of rest. This deepens the imbalance and speeds the transition from functional overreaching to non-functional.
Low energy availability deserves separate mention. Training against a background of a chronic deficit of calories and carbohydrates is very similar in its manifestations to overtraining, and these states often overlap. Modern authors advise checking energy balance in every athlete suspected of overtraining.
Biological mechanisms: what science knows
There is no single explanation for overtraining; instead there are several hypotheses, each of which describes part of the picture. The glycogen hypothesis links the state to chronically low glycogen stores in the muscles due to insufficient carbohydrate intake. However, overtraining has also been described in athletes with normal glycogen, so this hypothesis is not exhaustive.
The cytokine hypothesis, proposed by L. Smith, suggests that repeated micro-damage to tissues without full recovery triggers systemic inflammation. Pro-inflammatory cytokines act on the brain and can explain "sickness behaviour": fatigue, low mood, disturbances of sleep and appetite (Smith, 2000).
Another group of hypotheses concerns neuroendocrine regulation — the "hypothalamus — pituitary — adrenal glands" axis and the autonomic nervous system. A systematic review of hormonal studies showed that the data are contradictory: basal levels of cortisol or testosterone often do not differ, whereas the hormonal response to stimulation may be blunted (Cadegiani & Kater, 2017).
Most likely, overtraining is a multifactorial state in which energy deficit, inflammation, changes in neuroendocrine regulation and psychological stress are combined. That is precisely why the search for "a single marker" has so far yielded no result.
Pharmacology: masking and provocation
The link between overtraining and pharmacology is twofold. On the one hand, some drugs mask early symptoms. Stimulants and high doses of caffeine allow one to train "through fatigue", while painkillers and non-steroidal anti-inflammatory drugs dampen the pain that should have been a signal to reduce load.
On the other hand, anabolic steroids speed muscle recovery and allow one to withstand larger volumes. However, tendons, ligaments, the nervous system and the heart adapt more slowly than muscle mass. This creates a gap between what an athlete "can lift" and what the other systems can withstand. The Endocrine Society, in its scientific statement, describes a wide spectrum of cardiovascular, psychiatric and endocrine risks of such substances (Pope et al., 2014).
After stopping androgen use, suppression of one's own hormonal axis develops. The symptoms of this state — fatigue, apathy, reduced motivation, a drop in strength indicators — are very similar to overtraining, and they are easily confused. Correct diagnosis here requires a hormonal examination.
"Cutting" drugs — thyroid hormones, clenbuterol, diuretics — combine a stimulating effect with heightened catabolism and electrolyte losses. Against a background of a calorie deficit, they increase cumulative stress on the body and can speed the development of non-functional overreaching.
- stimulants and painkillers — mask early signals;
- anabolic steroids — increase the volume perceived as "tolerable";
- androgen withdrawal — mimics the symptoms of overtraining;
- weight-loss agents — heighten energy and hormonal stress.
Who is in the risk group
Overtraining is most often described in endurance sports — running, swimming, cycling, rowing — where large volumes are the norm. However, strength athletes, combat-sports competitors and team-sport players are not immune either, especially during periods of a dense competition schedule.
The risk group includes athletes who combine training with hard work or study, have unstable sleep, travel frequently across time zones or keep a low weight for competition.
Amateurs who train "on enthusiasm" without planning are also at risk, although their absolute volumes are smaller. What is decisive is not the athlete's level but the balance between stress and recovery for the specific person.
A separate group is people who use pharmacology without medical supervision. They often train with volumes unattainable without drugs and at the same time carry the risks of hormonal and cardiac disturbances.
Editorial conclusions
Overtraining is the extreme point of a continuum that begins with normal, planned overreaching. Its main cause is a prolonged imbalance between cumulative stress and recovery, not merely excessive training.
The mechanisms of the state are multifactorial: energy deficit, inflammation, changes in hormonal and autonomic regulation, psychological load.
Pharmacology does not protect against overtraining but often masks its symptoms or provokes similar states, in particular after withdrawal from anabolic steroids.
We also recommend reading our materials on the prevention and diagnosis of overtraining, on chronic fatigue in athletes and on the recovery of the hormonal system.
References
- Meeusen R, Duclos M, Foster C, et al. Prevention, diagnosis, and treatment of the overtraining syndrome: joint consensus statement of the European College of Sport Science and the American College of Sports Medicine. Med Sci Sports Exerc. 2013;45(1):186–205.
- Halson SL, Jeukendrup AE. Does overtraining exist? An analysis of overreaching and overtraining research. Sports Med. 2004;34(14):967–981.
- Smith LL. Cytokine hypothesis of overtraining: a physiological adaptation to excessive stress? Med Sci Sports Exerc. 2000;32(2):317–331.
- Cadegiani FA, Kater CE. Hormonal aspects of overtraining syndrome: a systematic review. BMC Sports Sci Med Rehabil. 2017;9:14.
- Kreher JB, Schwartz JB. Overtraining syndrome: a practical guide. Sports Health. 2012;4(2):128–138.
- Pope HG Jr, Wood RI, Rogol A, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341–375.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
