The IYTL exercise are very effective to stabilize the shoulder joint. That means they strengthen the muscles in the back of the shoulder, preventing the shoulder from rolling forward. This leads to less compression and grinding in the joint, less inflammation and pain.
Tips on performing: I recommend you begin these standing straight up looking in a mirror, so there is very little load on your shoulder muscles as possible. Concentrate on form. Your targets should be relaxed movement and no pain. Once you feel stronger, progress to standing, bent over at a 45-60º angle with a straight back. Or you can lie on a bench chest down as in the video. Once you feel strong and confident, you can start add dumbbells, 1 lb in each hand. Increase by a pound or so over time but do not loose your emphasis on form.
IYTL Shoulder exercises
If you're new to these, start with the standing position for 2-3 weeks before progressing to bent-over. When practicing bent-over IYTL's, keep your back and core braced (straight back, a healthy curve in the low back).
I show all the movements in this video, but include a link to the Eric Cressey video because the T is so important and he coaches it so well.
T's or Band Pull-Aparts with Eric Cressey - this is the T exercise from the IYTL exercises, explained in greater detail.
These are shown standing with a resistance band, which is fine if you've been performing these long enough to feel confident in your ability t do them with resistance. If you're just starting, do them standing straight up with the emphasis on form.
When you feel stronger and more confident, progress from standing to bent-over at a 30-45 degree angle. After that, you can add weight in the bent-over position, such as 1 lb in each hand. Btw, a can of soup is one pound. Increase by a pound or so over time but do not loose your emphasis on form.