Open up the side of your torso and breathe into the stretch.
Lean straight to the side, do not let your chest rotate forward or back.
Reaching one arm overhead and easing sideways opens up the entire flank, from the hip up through the obliques and along the ribcage to the lat. It is held one side at a time, and slow breathing into the stretched side is what actually deepens it, each exhale buying a little more length. Perfect between heavy sessions or after a day hunched over a desk.
The whole side of your torso, the obliques and the muscles along your ribs and up toward your armpit. You should feel one long line of stretch from your hip to your reaching hand.
20 to 40 seconds per side is plenty, breathing slowly into the stretched side. Ease in gradually rather than dropping straight to your end range.
Rotating forward or back is your body escaping the stretch. Keep your chest facing straight ahead and bend purely sideways, even if that means less range. A shorter, honest side bend beats a deep twisted one.
