Another important muscle group to stretch is your chest muscles, or pectoral ("pec") muscles. They have a tendency to become tight as a result of working with your hands in front of your body at a desk for long periods of time. When your chest muscles become tight, they begin to pull your shoulders forward, affecting your posture as well as neck, back and shoulders. A good stretch to counteract this is called the "Doorway Stretch." This stretch is done standing up in a doorway, with both arms out to the side and elbows bent. Place your forearms and palms against the door frame. From this position, gently lean forward into the door frame until you feel a stretch through your chest and the front of your shoulders. If you can't rest both forearms against the door frame, try this stretch one arm at a time. This should be held for about 30 seconds.Lastly, stretching the sides of your neck, or your upper trapezius ("trap") muscles is important as well. These muscles become tight due to poor posture and/or improper ergonomic setup at work. This stretch can be done just sitting in your chair. To stretch your right upper trap muscle, place your right arm behind your back. With your left arm hold onto the right side of your head and gently pull left until a stretch is felt along the right side of your neck. Repeat this stretch in reverse for the left side of your neck. Try these stretches throughout the work day or at the end of a long work day. Regularly stretching the hip flexors, chest and neck will keep these tight muscles from pulling on your body and help you maintain better posture while sitting at your desk.