Which of the following hormones, if increased at baseline, may be indicative of overtraining?

When baseline levels of cortisol are increased, it can be indicative of overtraining. Cortisol is a stress hormone produced by the adrenal glands in response to physical and emotional stress. In a balanced training program, cortisol levels fluctuate but typically return to baseline after workouts. However, when a person is overtrained, cortisol levels can remain elevated due to the chronic stress the body experiences from excessive training without adequate recovery.

This prolonged elevation can lead to various negative outcomes, such as increased fatigue, diminished performance, and compromised immune function. Therefore, monitoring cortisol levels can be an important factor in assessing an athlete's recovery and overall training status. In contrast, while testosterone, insulin, and growth hormone each play vital roles in physical performance and recovery, they do not serve as direct indicators of overtraining in the same way that elevated cortisol does.