Watch P90X2 - X2 Shoulders + Arms (2013) : Full Movie Online Free Shoulder instability can lead to an assortment of injuries as we age. By keeping our shoulders and arms strong an din balance, we can avoid breakdowns. And that - along with looking good in short-sleeved shirts - is the philosophy behind the creation of X2 Shoulders + Arms. Keep shoulders and arms strong and in balance. And look great in sleeveless shirts.