Here’s a new forearm stretch you can do besides the typical palm down palm up ones.
Kneel on your left leg.
Take your right arm and put it out straight with your elbow resting on your right knee.
Finger up and palm facing away from you.
Take your thumb and pull it downward while keeping your arm straight and your fingers up.
Then slightly rotate your shoulder and fingers to the right while keeping your thumb pulled downwards.
You should feel this on the inside of the middle of your elbow (where they take blood) and on the top of your forearm.
This stretch gets the Pronator Teres muscle which is responsible for pronating the arm. Overuse of this muscle (ie pitching) can sometimes shorten the muscle, causing it to be tighter and to inflame the underlying nerve. This is why you sometimes get tight in the middle of your forearm. The tricky part is that not throwing also shortens the muscle, causing it to micro-tear when you throw again. So make sure you’re using the stretch just as often as our internal and external shoulder stretches to ensure we’re loose.