Aaron Case Blogs on Running/Walking Techniques
I wanted to follow up on Lynn's excellent advice about how to relax your shoulders and upper body when running and walking. I have used her advice very successfully myself.
At this point in your training program, you may find that your shoulders are up around your ears especially at the end of a run. I know that in the highest mileage weeks that my legs start to ask for help from my upper body. The primary driving force for forward propulsion should be you gluteal (butt) muscles with your quadriceps (front thigh) and calf muscles providing more of the lift so that you don't run yourself into the ground - literally.
These "lifting" muscles will start to fatigue, especially your quadriceps because these muscles also act (contract eccentrically) as a shock absorber as your knee bends to cushion your landing. In other words, upper body tension can be a sign that you are making a futile attempt to lift and twist your body to compensate for tight/fatigued/weak quadriceps and calf muscles.
You may just need some extra rest/time-off/cross training, adding some simple body weight squating exercises to your routine and/or stretching/massaging your quadriceps and legs in general more frequently.
In summary, during your run, follow Lynn's great advice. If the tendency to use you upper body excessively persists, think about the above compensation mechanisms.
Good luck and hang in there!
Aaron Case at www.FastTrackChiro.com
Chiropractor and Active Release Techniques provider