Arm carriage refers to how you hold your arms when you run -- the most important part of your running technique.

The ideal way to hold your arms is so that your thumbs brush by or just barely below your hipbones with each step. If you've been holding your arms too high, you'll think this position is too low, but it's not. You have far more power when you run with your thumbs brushing by your hipbones.

To determine how you're holding your arms, run in place in front of a mirror or ask a friend to take a video or picture of you, from the front, as you run.

Your arms should never cross your midline (the imaginary line that runs down the middle of your body, from right between your eyes down to your navel). This is called crossing over. If you practice actually brushing your thumbs by your hipbones as you run and also keeping your hips still, you won't be able to cross this midline.