There is some science behind this but its not 100% down to the posterior delt. Firstly internal rotation of the shoulder could be caused upper crossed syndrome. This is basically where the pec major and minor, upper trapezius and levator scapulae become tight and the serratus anterior, rhomboids and neck flexors become inhibited or weak. This often leads to a tight thoracic region. So in order to firstly address upper crossed syndrome we need to stretch the tight muscles and activate the inhibited/weak muscles. Once this problem has been resolved we can look at shoulder biomechanics. Internal rotation reduces the space between the shoulder joint. This means that the structures within the joint can get irritated due to constant rubbing. This creates pain. One way to combat this pain is to increase the shoulder joint space. This is where your posterior deltoid comes into play as it is an external rotator of the shoulder along with infraspinatus and teres minor. Strengthening the external rotators has been shown to increase the shoulder joint space. The best way to do this is with a resistance band. The link below shows how to do these. I would place a rolled up towel between the arm and the side of the body to maintain a gap. Hope this helps.

 

http://www.google.co.uk/imgres?imgurl=http://www.physioadvisor.com.au/assets/256/images/13846256%28400x400%29.jpg&imgrefurl=http://www.physioadvisor.com.au/10660350/shoulder-instability-shoulder-subluxation-phys.htm&h=354&w=400&sz=108&tbnid=P46C2-NRrxHwFM:&tbnh=90&tbnw=102&zoom=1&usg=__hu47baMetsfls2qvWcdfruqWeLQ=&docid=7S2QPYbpBLP-SM&sa=X&ei=ViBwUrj3AYrY7AbkroD4Dw&ved=0CDYQ9QEwAQ

Awesome. Thanks for the info. I will try this exercise, but how heavy should the resistance be for this exercise?

Haha yeah, I'll try the bent over dumbbell raises when I'm strong enough to do so, right now im doing the same exercise but with lighter resistance bands. And yeah I've heard stories of people having shoulder injuries from not exercising their rear delts, or having over developed front delts. Might be bro science, but it seems legit.

There is some science behind this but its not 100% down to the posterior delt. Firstly internal rotation of the shoulder could be caused upper crossed syndrome. This is basically where the pec major and minor, upper trapezius and levator scapulae become tight and the serratus anterior, rhomboids and neck flexors become inhibited or weak. This often leads to a tight thoracic region. So in order to firstly address upper crossed syndrome we need to stretch the tight muscles and activate the inhibited/weak muscles. Once this problem has been resolved we can look at shoulder biomechanics. Internal rotation reduces the space between the shoulder joint. This means that the structures within the joint can get irritated due to constant rubbing. This creates pain. One way to combat this pain is to increase the shoulder joint space. This is where your posterior deltoid comes into play as it is an external rotator of the shoulder along with infraspinatus and teres minor. Strengthening the external rotators has been shown to increase the shoulder joint space. The best way to do this is with a resistance band. The link below shows how to do these. I would place a rolled up towel between the arm and the side of the body to maintain a gap. Hope this helps.

 

http://www.google.co.uk/imgres?imgurl=http://www.physioadvisor.com.au/assets/256/images/13846256%28400x400%29.jpg&imgrefurl=http://www.physioadvisor.com.au/10660350/shoulder-instability-shoulder-subluxation-phys.htm&h=354&w=400&sz=108&tbnid=P46C2-NRrxHwFM:&tbnh=90&tbnw=102&zoom=1&usg=__hu47baMetsfls2qvWcdfruqWeLQ=&docid=7S2QPYbpBLP-SM&sa=X&ei=ViBwUrj3AYrY7AbkroD4Dw&ved=0CDYQ9QEwAQ

You will do dumbbell bent-over raises when you are strong enough?

 

Come on man!  Grab the 5 pound dumbbells and get to work! :)

 

4 sets of 12-15 reps with a nice controll TEMPO.  You will love it!

I recently found out that exercising the rear delts will help pull back your shoulders so they won't rotate inward. This sucks because I've been working out for a year, and I've never trained that before. So what are some good rear delt exercises, both isolation and compound. i only have dumbbells and resistance bands, no access to a gym. I know a prone cobra is supposed to help fix/prevent internal shoulder rotation, so how do you do those? Also what are some good stretches to prevent internal shoulder rotation?

My favorite isolation movements for the rear delts are the reverse pec deck, the reverse cable fly, and the rope cable face pull. All 3 of these exercises work well. Typically for each shoulder workout I will pick 1 isolation and 1 compound exercise for the rear delts. I also feel that doing a rear delt exercise first in your shoulder routine helps to loosen up the shoulders which makes the shoulder presses go more smoothly. I start my shoulder workouts with a reverse pec deck and then about mid way through the workout I like to do a seated bent over dumbbell fly. 4 sets of 8-15 reps for both exercises. For the seated bent dumbbell fly it's very easy to lose proper form. You dont need a lot of weight to really feel this exercise. I usually start with the 15's and end out with the 25's for my 4th final set. Keep a slight bend in your elbows and really contract the rear delts at the top. Lower the dumbbells slowly with good control to keep more tension on them. If you cant resist the weight on the negative portion of the reps then lighten the weight a little.