Runners tend to avoid working out tension in their shoulders. Over the years of coaching when I correct a runners arm swing, that is swing their arms via elbows and NOT a shoulder roll the stride generally smooths out. That is because there is a strong connection between the elbows and hips. The Kenyan runners have a great expression ‘run with your hips and elbows’, interestingly enough they don’t say ‘run with quads and calf’s’. Try these shoulder exercises, you will need to them at least once a week, you can use a belt no need to buy any straps.