Shoulders are only one of two ball and socket joints in your body (hips) and can require additional movement prep prior to jumping into a workout.
Performing a quick but intentional warm-up can provide lot's of benefits including increased blood flow, activation of the supporting muscles, and increased mobility.
The PVC Shoulder Warmup (around the world) is one of our favorite quick before class movements to incorporate because of the range of motion it takes the shoulders through and how easy it is to get done.
PVC bars are readily available at Reign Fitness but if your gym doesn't have one, you can easily use a resistance band. If your gym doesn't have a band, they're cheap to buy and can easily be thrown into a gym bag.
Utilizing a band is also a great way to scale this mobility warmup exercise because of the give it provides.
Set-up with a wide grip on the PVC bar, feet shoulder width apart, and. slowly rotate one arm behind your back followed by the the other. If you need a little extra help to get that arm over your head, be sure to keep a slight bend in your arm throughout the movement.
If you see any overhead pressing (DB press, BB Press, Thrusters) than be sure to incorporate this quick shoulder mobility exercise before class gets going.