"Good posture is the key to everything" and my head, low and behold, is attached to the rest of my spine." Both are things I've taught every client, Egoscue University student, and Posture Alignment Specialist I've worked with over the last 15 years.
Nate talks about how you should not hold your phone while looking at it and you can clearly see this is terrible posture:
The best way to guarantee good running posture and improve your running performance and decrease injury risk is to get a full posture alignment analysis from a certified and experienced Posture Alignment Specialist and Advanced Exercise Therapist. They will be able to show you what your dysfunctions and compensations are and how you can correct them with simple e-cises designed just for you. You can receive a FREE Posture Evaluation here.
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