Arm circles are a simple exercise used to warm up the shoulders and improve flexibility. To perform arm circles, stand with your feet shoulder-width apart and extend your arms out to the sides at shoulder height. Begin making small circular motions with your arms, gradually increasing the size of the circles. This exercise can be done in both clockwise and counterclockwise directions. It is often included in warm-up routines for sports or fitness activities, helping to prepare the upper body for movement and reduce the risk of injury.