The NEWF Bag Jack-Knife to Push Away Core Strap Exercise will leave your core with a deep burn for days.  

Step 1: Adjust the NEWF Bag shoulder strap height to 6-12 inches off the ground and put one foot into each handle

Step 2: While in a push-up position, pull your hips up as high as you can while keeping your arms and legs straight.

Step 3: Once you get your hips as high as possible, lower your body back towards the starting position. Instead of stopping at the start position, continue to push your body back as far as you can while keeping your arms straight and core flat.

Step 4: Once extended to your limit, bring yourself back to the starting position.