This movement is great to loosen up the entire body, but it will also strengthen your shoulders and lower back.
Begin by taking a shoulder width stance with a kettle bell in between your legs. Squat down and grip the kettle bell with both hands in a double overhand grip. Bring the kettle bell to your knees. Next, slightly swing the weight back further in between your legs. Now, explosively pull the weight out and up so that it swings to shoulder height. You should be pulling with the muscles of your back and shoulders to get the weight moving and to stop it at the bottom. Next, allow the weight naturally fall back to the starting position. Repeat until you have completed the set.
This exercise can also be done with a dumbbell that has been turned on its side. Also, this exercise can be done one arm at a time with either dumbbells or kettle bells.
Make sure you are warmed up or you have to begin with very light weights. Since, this is an explosive exercise, you should be careful not to strain any muscles.