Good thoracic spine mobility is vital for pain-free shoulders, especially if your sport requires you to raise your arms overhead.
Thoracic spine mobility is another one of those areas of mobility that are compromised by our modern lifestyles. These simple mobilisations will make an enormous difference to your thoracic extension and thus your ability to get your arms overhead without placing undue stress on your lower back or shoulder capsule.
As mentioned in the video, you want to work on this over a period of days to make the initial change and then return to it a few times a week, especially if you spend a lot of time driving or sitting at a desk.
While I use yoga tune-up balls in the demo, you can use tennis balls, lacrosse balls or anything of a similar size. Just tape them together using athletic tape to make the peanut shape.
I have been known to use the padded arm of the sofa in place of a foam roller. Anything of the approximate shape of the roller will do the job very nicely.