Fix Your Running Form

Arms and hands

The arms play an important supporting role in balancing and propelling your body while running, keeping it moving smoothly and straight ahead. Your arm swing should be predominantly forwards and backwards, with your hands barely crossing over your core.
Swinging your arms sideways is inefficient and, along with excessive shoulder rotation, can sabotage your stride.
Arms, wrists, hands and fingers should be loose and relaxed, with elbows bent at 90.

Stretch: elbow raise. Stand up straight, with your feet together and your arms down by your sides. Raise one elbow behind you as high as possible. Hold the stretch, then relax the arm and let it swing forwards as if you're running. Try to raise your elbow slightly higher with each stretch.