A certain level of "training overload" is essential for successful physiological/psychological adaptations & performance improvement. However, athletes and coaches need to be mindful & calculated about getting the balance right between adaptive loading, and unsustainable overload or inadequate recovery.

Endurance athletes tend to be the most vulnerable to developing prolonged maladaptation, or an overtraining syndrome of sorts. Typical initial symptoms may include; feeling constantly fatigued; experiencing mood, sleep & appetite disturbances; impaired neuro-chemical & hormonal regulation; and a decline in training and competition performance.

Unfortunately, there is no one simple test available to diagnose over training syndrome (OTS). However, given that a chronic decline in sport/exercise performance is consistently prevalent amongst overtrained athletes, a performance test (click here to read more >) is an essential step in diagnosing OTS. Additional baseline physiological measures also provide a relative gauge on athlete responsiveness to a range of sub-maximal & maximal workloads. 

Persisting without appropriate intervention can lead to the development of more serious health concerns, including, but not limited to: chronic fatigue; heart rhythm disturbances; down-regulation of some genes normally expressed in abundance; hormonal dysfunction & immunosuppression, amongst others.

Science in sport & health.