Thread: Overtraining

I am pretty new to the forums here. One thing I learned here is not to overtrain. I understand that to much volume can result in overtraining. Now with that said, is there a set number of sets and reps that would be considered overtraining? How do you know if you are overtraining or not? A lot of people here seem to think 10-12 sets is way to much for a body part. I see these people in my gym doing 9 sets for triceps and 9 more for biceps. These guys look pretty big too. Are they overtraining?
Example workout:
Flat Bench 4 sets
Incline Bench 4 sets
Pec Deck 4 sets
Is that workout overtraining?

This is my chest workout
Flat Bench 5 sets
My chest is sore for two days after that. Am I overtraining or undertraining?

Ok based on a standard bodybuilding split routine training each body part once per week with a low-average out of gym active level with good calorie + diet while beiing natural i can tolerate around 6 sets for large and 4 for small this is around my maxium i can do for prolonged periods, i might be able to do 9 for large and 6 for a small, for a short time but i have found doing either the 6/4 or 9/6 no way near as productive then when i train with about 2-4 for large 1-2 for small and each body part every 5 days.