Most runners run with extremely bad posture:
• Elbows are stiff and locked (often raised)
• The body is leaning forwards or stooping; either at the neck or collapsing at the bottom of the rib cage
• Shoulders are lifted; often one higher than the other
• Considerable tension in the upper body
• Frozen sacroiliac; immobile
• Knees twisted (the foot flicks out sideways)
• Weight is bearing heavily down into the knees
• The skeleton is not moving freely, naturally or comfortably
This would be bad posture for any form of exercise. It causes serious fatigue and adverse wear and tear on the body.
The tension in the body uses energy and tires you out.