Many of the form flaws we looked at earlier stem from a tight upper body. Increase your chances of running with a smooth whole-body motion by maintaining good upper-body flexibility. The shoulders are key here—think of them as your arms’ hips in which you want good range of motion in all directions. Do stretches that target the different shoulder muscles, such as internal and external rotators.
Also work on your neck so that you can hold your head loosely over your body when you run. Jim and Phil Wharton’s materials show an excellent series of stretches for neck and shoulder muscles. As with the feet and ankle stretches, these are easy to sneak in a few times a day as a great way to reboot your body and counteract too much sitting, typing, and time in front of screens.