The most prevalent disease in athletes is now unveiled: researchers discovered the causes of ‘overtraining syndrome’

The world has more than one billion of physically active subjects and millions of athletes – numbers that are quickly growing. Despite several health benefits, up to half of the athletes may be affected by overtraining syndrome. Now, a study just published at the British Medical Journal (BMJ) finally revealed the actual causes of the disease.

Almost all athletes have likely heard about overtraining syndrome, which is extremely popular in social media and websites (more than 411,000 results in Google). By analyzing 117 parameters in more than 50 participants from three different groups, this brand-new study was able to elucidate many of the missing gaps to explain the origin and consequences of this syndrome. Overtraining leads to an unexplained decrease in performance and a chronic state of fatigue, many times associated with low sex drive, lack of muscle recovery, and mental disturbances, and initially not caused by any organic, hormonal, or metabolic clear dysfunction.

Researchers have always struggled to find markers and causes of this syndrome. Now, the study can help to understand how it occurs. “Although overtraining syndrome was initially correlated with excessive training (from which the name “overtraining” was derived), the periodization of the training sessions, largely spread among most sports practitioners, unexpectedly failed to lead to its reduction, showing that other important factors were as or more important triggers”, explains the endocrinologist Flávio Cadegiani., MD, MSc, PhD, and the main researcher responsible to sign the study.

Doctor Endocrinologist Flavio Cadegiani

The study just published at the British Medical Journal (BMJ) finally revealed the actual causes of overtraining syndrome. By joining multiple behavior aspects, including eating, social, sleeping, and psychological patterns, with basal and stimulated hormones, muscle, inflammatory and immunology markers, and analyses of body composition and metabolism, and simultaneously comparing all these parameters in athletes affected by actual overtraining syndrome with both healthy athletes and sedentary controls, the Endocrine and Metabolic Responses in Overtraining Syndrome (EROS) study was able to elucidate the once unknown root causes and mechanisms that lead to overtraining.

“The EROS study discovered that dysfunctions in overtraining syndrome were neither overt nor absent, but relatively altered, as the majority of the parameters were altered when compared to healthy athletes, but within the reference ranges for general population. It means that this syndrome results from a mix of losses of the multiple biochemical and hormonal conditioning processes found to occur in athletes, which we termed as ‘mix of deconditioning processes’. Basically, the conditioned athlete became ‘hormonally and metabolically deconditioned’, which leads to a ‘physical decondioned state’, represented by a decrease in sports performance, the hallmark of overtraining syndrome. Ultimately, this novel finding elucidates the underlying reason of the key aspects of overtraining syndrome.”, explains doctor Cadegiani.

Meanwhile, the EROS study also found that insufficient calorie, protein, or carbohydrate intake, poor sleep quality, or concurrent excessive cognitive effort were the prevailing predictors of this syndrome, not excessive training, as previously suggested.

With all the new findings, authors suggested that “Paradoxical Deconditioning Syndrome” could be a more appropriate and descriptive name for the previous misnomer (‘overtraining’). In summary, the researchers from the EROS study recommend a change in the extensively disseminated name “Overtraining Syndrome”.

Finally, the study also discovered the existence of multiple intrinsic and independent metabolic and hormonal adaptations to exercise, in addition to those known to happen in cardiovascular and muscular systems. This serendipitous finding may explain some of the health benefits and progressive improvement observed in athletes that could not be fully explained previously.

“Since we now know that ‘overtraining syndrome’ is a syndrome caused by ‘hormonal and metabolic deconditioning’ that leads to ‘physical deconditioning’, and can be triggered by eating, sleeping, or social issues, we may now be able to effectively prevent this extremely common sports-related disease. One less problem for athletes? Hopefully, yes”, says the researcher, doctor Flávio Cadegiani.

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