Which of the following is a sign of overtraining?

Chronic fatigue and decreased performance are significant indicators of overtraining. When an athlete engages in excessive training without adequate recovery, it can lead to physical and mental exhaustion. This state results in the body's inability to adapt to the training stimulus, ultimately causing a decline in performance, a feeling of constant fatigue, and a lack of enthusiasm for workouts.

In contrast, improved athletic performance, increased motivation to train, and better sleep quality are all signs of proper training regimens and recovery. They indicate that the body is responding positively to the training stimulus rather than being overwhelmed by it. Therefore, the presence of chronic fatigue and decreased performance is a clear sign that the body is struggling to cope with the training load, marking it as a key indicator of overtraining syndrome.