If any of the aforementioned actions describes the beginning of your upper-body workout routine, you're not doing much to prepare your muscles for the activity they're about to endure.
One of the most important parts of a good workout program is the warm-up. When planning these exercises, it's not as simple as throwing your arms in circles and conducting some light stretches. These exercises should increase your body temperature, improve joint lubrication, increase mobility and groove proper movement patterns.