Scientists from Brazil have found out that the “culprit” of fatigue, pain and decreased immunity during excessive exercise is an excess of PARP1 protein. The results of the study are published in the journal Molecular Metabolism (MolMeta).

It is known that excessive physical activity without sufficient recovery can not only reduce athletic performance, but also cause serious damage to the body. In extreme cases, overtraining syndrome develops: endurance deteriorates, appetite decreases, chronic fatigue accumulates, muscles ache, the risk of injury increases, and immune and metabolic processes are disturbed.

To find out what exactly triggers such changes, scientists conducted an experiment on mice. The animals were forced to move until they reached exhaustion. After such training in rodents naturally observed a sharp drop in performance, apathy and stress behavior - for example, freezing or compulsive licking of hair. 

The analysis showed that the activity of PARP1, a protein responsible for repairing damaged DNA, was dramatically increased in their muscles. Scientists explained that its function is to protect cells under stress, but in excess it disrupts the work of mitochondria, provokes inflammation and worsens energy metabolism.

According to Barbara Krisol, one of the authors, a similar clinical picture is observed in muscular dystrophy, obesity and even cachexia - extreme exhaustion in cancer patients.

It was also found that mice injected with a PARP1-blocking drug did not develop symptoms of overtraining despite high exercise. However, this drug is used in the treatment of cancer and causes severe side effects, so it can not be used to accelerate the recovery of athletes. Scientists are now looking for gentler and safer ways to regulate PARP1 levels, including the use of natural compounds.