Arms Stretching - Hanging From a Bar With Supinated Grip.
Muscles involved: Biceps brachii, brachioradialis
With arms externally rotated and forearms supinated (the palm of the hand facing backward), hang suspended from a horizontal bar. Relax the body during the few seconds that the stretch lasts and then return to the ground in order to “release” the muscles.
This is exactly like the starting position for performing “chin-ups” for the back and biceps. And it is precisely this pair of muscle groups, the back muscles and the elbow flexors, that are being stretched during this exercise. The only things to note are knowing how to relax the body and not to maintain a constant tension in the arms, which would prevent them from being stretched, and use only the forearms and hands to support the weight of the body.
As an alternative, you can try to hold on to a lower bar and keep the feet on the ground, but then progressively take all of the body weight off the feet until your whole bodyweight is hanging, even if your feet may still be touching the ground.