Fatigue is one of the earliest symptoms of overtraining. Some experts call the earliest symptoms, those that resolve quickly if you just decrease the workout intensity on every third or fourth day, overreaching rather than overtraining.
If you continue overreaching without recovery, you may experience some of these symptoms of overtraining:
Tension
Irritability
Decreased appetite
Restless sleep
Loss of sexual desire
More aches and pains
Declining athletic performance
In the more severe form of the overtraining syndrome, the following can occur:
Depression
Menstrual irregularities in women
More significant sleep problems
Prolonged muscle soreness
Markedly diminished athletic performance