Is Overtraining a Myth? Muscle Stress Explained

published by: Debbie Luna
Last Updated:
November 11, 2022

Athletes, especially those who participate in competitive sports, routinely reach the limits of their physical abilities during demanding training schedules. Overtraining syndrome thus develops when the athlete’s training schedule lacks adequate rest and recovery periods. In the bodybuilding community, however, overtraining is commonly disregarded as an excuse to slack off on training.

Overtraining syndrome consists of a spectrum that progresses from functional overreaching and nonfunctional overreaching to overtraining, and is widely tackled by medical journals.

It is a phenomenon caused by stress accumulation brought about by training and other life stressors compounded by inadequate rest, hence resulting in long-term deficits in performance. However, the textbook definition of overtraining syndrome is more often seen in high level endurance athletes rather than in bodybuilders.

While overtraining does exist, it is important to understand why this phenomenon is increasingly disregarded as a myth by some bodybuilders and weight-training enthusiasts. Distinguishing between overtraining as recognized by medical journals and reduced physical performance due to other factors is necessary in preventing a plateau in fitness progress and long-term performance decrements.

What is Overtraining Syndrome?

Overtraining syndrome is defined as a medical condition that mainly presents as a decline in performance with accompanying maladaptive responses. This condition is said to be the result of an imbalance in exercise stress load, non-training stress load, and rest.

Recovery from this condition may take months to years. However, before reaching the state of overtraining syndrome, the athlete first enters functional overreaching, nonfunctional overreaching, and overtraining.

Functional Overreaching

Intense training regimens may lead to a decline in performance particularly in the absence of adequate rest and recovery periods. When appropriate rest is present, enhanced performance is observed following a temporary decrease that typically disappears within 3 to 14 days; This is known as functional overreaching.

Functional overreaching is used by high level athletes and coaches due to its benefit in improving performance. Because of the adequate rest periods provided, the body is able to compensate for the stress brought about by training.

Nonfunctional Overreaching

In the event that functional overreaching continues for weeks, the body may enter a state of nonfunctional overreaching defined as a more severe form of overreaching.

Nonfunctional overreaching leads to a performance decline with the presence of neuroendocrine and/or psychological symptoms. Although recovery from nonfunctional overreaching also takes several days to weeks, performance decline lasts longer than that in functional overreaching.


When training is further intensified without providing adequate periods of rest, overtraining may develop. Overtraining is defined as a long-term (weeks to months) decline in performance capacity with or without psychological and physiological signs of maladaptation.

This is primarily differentiated from nonfunctional overreaching in terms of the time needed for recovery. An athlete moves from overtraining toward overtraining syndrome with added stress and inadequate rest.

Varieties of Overtraining Syndrome

Overtraining syndrome is divided into a hyperarousal and a hypoarousal form. Hypoarousal, also known as parasympathetic or Addison’s overtraining syndrome, is more often diagnosed in endurance athletes such as swimmers, long-distance runners, and cyclists.

Hyperarousal (also sympathetic or Basedow’s overtraining syndrome), on the other hand, is more common in power athletes including sprinters, jumpers, and weightlifters.

While the two forms present with similar symptoms, the hyperarousal form occurs less frequently, thus overtraining is not often seen in bodybuilders.

Symptoms of Overtraining

The most common complaint of individuals who experience overtraining is underperformance. Because earlier manifestations such as fatigue, heavy muscles, and depression are ignored, chronic affectation of performance sets in. Thus, early recognition of overreaching and overtraining is important in preventing progression.

Around 90% of cases report sleep disturbances. This may present as difficulty in sleep onset, nightmares, night awakenings, and feelings of inadequate sleep.

Other symptoms include loss of appetite, weight loss, decreased libido and competitive drive, palpitations, excessive sweating, and mood changes such as emotional instability, anxiety, and irritability.

The most serious symptom is that of recurrent infections including upper respiratory tract infections and other minor infections that occur when an individual attempts to resume training prior to full recovery; Infections are observed every few weeks.

Science Behind Overtraining

There are several hypotheses aiming to explain the pathologic mechanisms of overtraining syndrome.

Although there is still no definitive explanation for this condition, the cytokine and hypothalamic hypotheses are two concepts considered in overtraining.

Cytokine Hypothesis

The cytokine hypothesis states that the microtrauma acquired from intense training induces an acute inflammatory response. When activation of muscles and joints is prolonged without adequate rest, the acute inflammation shifts to that of a chronic state, thus amplifying inflammation.

Cytokines are immunoregulatory proteins that are released by immune cells and have varying effects on the body. The symptoms seen in overtrained individuals such as depression, fatigue, heavy muscles, and sleep disturbances can all be linked to the action of specific cytokines released during the inflammatory response brought about by muscle trauma.

Although the symptoms of overtrained individuals fit into the cytokine hypothesis, there are limitations surrounding this concept as only few studies have investigated the relationship between cytokines and overtraining.

Hypothalamic Hypothesis

A dysregulated hypothalamus is said to contribute to the symptoms of overtraining syndrome. In particular, the recurrent infections, fatigue, weight loss, and decreased competitive drive all fit into the hypothalamic hypothesis.

The hypothalamic hypothesis claims that the stress causing overtraining affects the hypothalamus leading to drastic changes in hormones, specifically cortisol.

Cortisol increases in the presence of stress, causing breakdown of molecules such as proteins. Because there is overwhelming stress in overtraining, cortisol is persistently elevated resulting in muscle breakdown instead of recovery.

However, in chronic states of overtraining, cortisol level may decrease as a result of adrenal insufficiency. This then leads to symptoms such as fatigue, depression, and lack of motivation.

Common Misconceptions on Overtraining

There is a common perception that overtraining is only caused by an increase in workout intensity. However, factors such as poor nutrition, inadequate rest, and other life stressors also contribute to overtraining.

Poor nutrition is either eating less than the body requires or consuming the wrong type of food. In order for the body to keep up with the demands of training, it must be provided with adequate nutrition. A proper balanced diet composed of enough proteins, fats, and carbohydrates allows the body to recover.

Inadequate rest and other life stressors also contribute to overtraining as these dysregulate the endocrine system, thus causing changes in hormone levels. These hormones are required in muscle building and repair.

In the bodybuilding community, overtraining is often disregarded as myth likely due to the infrequent occurrence of this condition in power athletes. Nonetheless, overtraining may still occur in bodybuilders and other power athletes especially when training is done without the use of rest or recovery days.

How to Prevent Overtraining

The main prevention strategy for overtraining is to incorporate adequate rest in training programs. The problem with this idea is that most athletes refuse to rest when advised.

A recommended alternative to a complete recovery day for endurance athletes is a five to ten-minute aerobic exercise at a pulse rate of 120-140 beats per minute.

This should be slowly built up over the course of 6-12 weeks. However, a once-a-week complete recovery day should still be applied. During recovery days, the individual should avoid their own sport as there is a tendency to increase exercise intensity right away.

Because overtraining is not very common in power athletes, there are no studies discussing the optimal prevention strategy incorporating rest days. In general, overtraining in power athletes can be prevented by resting for a few days to a week. Aside from preventing overtraining, this also helps the individual overcome plateaus.

Final Thoughts

Because the word overtraining has gained varying definitions outside the medical community, misconceptions are expected. Overtraining syndrome is a medically recognized condition that should be analyzed as a spectrum ranging from functional overreaching to overtraining. While functional overreaching is useful in training programs to enhance sporting performance, coaches and athletes should be mindful not to progress to nonfunctional overreaching and overtraining.


1. Carfagno, David G. DO, CAQSM1; Hendrix, Joshua C. MS-III2. Overtraining Syndrome in the Athlete: Current Clinical Practice. Current Sports Medicine Reports: January/February 2014 - Volume 13 - Issue 1 - p 45-51 doi: 10.1249/JSR.0000000000000027

2. Roy, Brad A. Ph.D., FACSM, FACHE. Overreaching/Overtraining: More Is Not Always Better. ACSM's Health & Fitness Journal: March/April 2015 - Volume 19 - Issue 2 - p 4-5 doi: 10.1249/FIT.0000000000000100

3. Fry AC, Kraemer WJ. Resistance exercise overtraining and overreaching. Neuroendocrine responses. Sports Med. 1997;23(2):106-129. doi:10.2165/00007256-199723020-00004


5. Budgett R. Fatigue and underperformance in athletes: the overtraining syndrome. Br J Sports Med. 1998;32(2):107-110. doi:10.1136/bjsm.32.2.107

Debbie (Deb) started powerlifting and Olympic lifting in High School as part of her track team's programming; She continues to train in order to remain athletic. Inspire US allows Deb to share information related to training, lifting, biomechanics, and more.
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