Did a little research for ya on the net is this what i found....
Five endurance-trained men were studied before, immediately after, and 3 months after overtraining, which was defined as twice the previous average weekly training volume with unchanged intensity.
Basal testosterone levels decreased to 5.37 +/- 67 ng/mL from 8.68 +/- 93 ng/mL immediately after overtraining and basal cortisol levels increased to 215.3 +/- 31 ng/mL from 145.7 +/- 27 ng/mL.
Both cortisol and testosterone levels returned to pretraining values 3 months after resumption of previous training volume.
Sperm count decreased significantly by 43% immediately after overtraining and by 52% 3 months after overtraining.
These results indicate that overtraining reduces testosterone levels, which is highly correlated with an increase in levels of cortisol.
Hope this answers your question.