Day 9 incorporates more core strength. A strong core allows you to punish the ground at push-off. After all, you can’t fire a cannon from a canoe. Day 9 practice revolves around the always favorite plank. Notice how we move from one position to the next or use arm/leg movements to challenge you further. A static plank is effective, but not run-specific. As always, be sure to listen to our cues to ensure you’re not cheating yourself or risking injury. We recommend using a yoga mat and for those who are fairly tight, a yoga block.