I have talked about this in other videos, and I have talked about this a lot in another video when it comes to shoulder pain.
How you do the vertical hanging exercise is you are grabbing the bar with your hands shoulder-width apart, and your arms are straight above. Then what you are doing is gradually add more and more of your body weight onto your arms, and you are looking for a light stretch in the shoulders. What we are not trying to do is rip the shoulders apart, what we are trying to do is lightly stretch the muscles in the shoulders and then also lightly loosen up that shoulder joint.
Once again if you are doing a lot of sitting and a lot of driving, we are losing some of that shoulder movement. What we want to do is add the Vertical Hanging to stretch out the shoulder muscles especially when it comes to overhead exercises, for example, barbell pressing or snatches.
Stretching out those shoulders muscles will end up making any overhead pressing movement, or any overhead movement, easier. If you are losing some of the range of motion to your shoulder, then you are putting more stress and strain on other parts of your body like your mid-back, your low back and your hips.
Typically, I get people to hang for about 15 seconds, using 25% of their bodyweight. Then do their next set of exercises. After that, fill-in by hanging with 50% of their bodyweight for 15 seconds, finally working all the way up to their full bodyweight. But you are going to increase the weight gradually on the arms, and then they are lightly stretching out those muscles around that shoulder joint.