Question

Is it safe to throw the day after you work on upperbody(shoulders, triceps, chest, etc.) in the gym?

Yes, because you are using pretty much different muscle groups.

The only concern I would have would be for the muscles of your shoulders. They would get a workout in both cases.

For that reason, I wouldn’t go all out.

Yes you can throw the day after. The only thing i would watch out for is maybe actual pitching the day after because sometimes just a tight shoulder, as Chris said, or a tight back or chest could result into a change or mechanics which does lead to injury. A way to keep this from happening is to stretch stretch stretch. Also as Chris said your not going to want to throw around Max Out weight the day before. I think as long as you stretch before and after pretty much anything you do with you arm regarding throwing or stregenthing you should be okay. If you happen to feel a little bit tight ease up on the throwing maybe or just try to long toss which i found tends to stretch your arm out. Just listen to your arm if it hurts…ease up.