If you carry a lot of muscle, chances are you have tight shoulders. That'll lead to aches and pains, and also prevent you from breezing through mobility-based movements like Turkish getups, snatches, or med ball throws.
The reason why football players are never mistaken for bodybuilders is because regardless of how much muscle they pack on, they're still able to move freely, have joint integrity, and achieve full ranges of motion, whereas watching bodybuilders sprint or perform any feats of athleticism can be a cringe-fest.
As far as the upper body is concerned, having good circumduction – the ability to move the shoulder a full 180 degrees – comes from a combination of flexibility through all muscles that cross that junction, and strength of the working muscles to pull your arm through the desired ranges. In short, that combo of strength and flexibility are what creates mobility, and it's probably something you need more of.
Medicine Ball Tomahawks
Medicine ball tomahawks truly hit the entire posterior chain when done correctly, but the focus is on the same shoulder mobility mentioned above.
Use a light medicine ball to start. Ten pounds should be plenty. The rules are simple:
- Keep wide elbows at all times. It's easy to do this exercise if you cheat by doing a biceps curl instead.
- Keep your chin tucked and neck packed. Craning your neck forward (into the floor) is just a compensation pattern that won't make for any positive improvement for the joint mechanics.
- Touch the medicine ball to the upper back and pause on contact. Raise everything else you can off the ground at the same time to create a full arched-angel position.
This movement will light up your weak lower traps and rear delts, and give you an honest indication of what your shoulder rotation looks like. There's no reason why you shouldn't be able to ace this movement, but you probably won't at first.