Thread the Needle

How to do it

Start on hands and knees. Slide the right arm under the chest, threading it through to the left side, palm facing up. Lower the right shoulder and right ear to the floor. The left hand can stay grounded next to the right shoulder, or — for a deeper version — reach overhead along the floor or up toward the ceiling. Hips stay over the knees. Hold and breathe, then switch sides.

Why it's good for runners

The thoracic spine — the mid-back — needs to rotate when you run, because every arm swing twists the upper body against the opposite leg's push-off. If the thoracic spine doesn't rotate, the lumbar spine has to, and that's how low backs get cranky over long runs. Thread the Needle is a passive thoracic rotation that pays off in cleaner arm carriage and a calmer low back.

Common mistakes

Don't shift the hips toward the opposite side when threading the arm through — the hips stay stacked over the knees, so the rotation actually happens in the thoracic spine. And don't grind the shoulder into the floor; lower as far as is easy, and let breath bring it the rest of the way over time.