Ever have one of those days that starts with stiff neck when you get out of bed, then you get off the train and your right shoulder hurts, at lunch time you notice your left hip hurts and by the time you get home you can hardly walk in the door? Of course you have. Unfortunately everything from your head to your toes is connected someway. This can certainly have negative effects on your mobility. A study out of The Journal of Orthopedic and Sports Physical Therapy looked at how neck limitation can affect your gait.
There were 14 subjects in the neck pain group and the control group. Each group performed treadmill walking at 3 different speeds for a specific period of time while the researchers performed a 2D video gait analysis. The researchers found the neck pain group had decreased trunk rotation as well as limited stride length.
How can your neck be such a limitation? Everything in your body is connected. All of our muscles connect via fascia which is similar to a web. If you have a tight muscle higher up in your body, the fascia will be tighter at that muscle which will pull on connected muscles lower down the chain. For runners, one of the most important chains of fascia is called the posterior chain. Most runners know the major players such as the calf muscles, hamstrings and gluts but they do not realize it includes the erector spinal muscles which run all the way up to the skull.
This is just another way to remind you the importance of stretching. Stretching your muscles will also stretch your fascia which will affect the fascia of the entire chain. Focusing on your neck posture should become a habit when you are at work, on the computer, standing on the subway; basically every moment of your life. Slow neck circles and stretching your upper traps can actually be helpful to do during the day, especially before you run!

Falla, D., Gizzi, L., Parsa, H., Dieterich, A., Petzke, F. People with chronic neck pain walk with a stiffer spine. Journal of Orthopedic & Sports Physical Therapy. February 2017.