Difficulty: Intermediate to advanced
Purpose: To increase core strength. This is different than other ab exercises that have spinal flexion. Here, this is called an isometric movement meaning, you contract the abs without flexing or extending the spine. This is great for increasing core strength in athletic movements.
Execution: Start above your kneecaps (or use a mat to avoid discomfort in the knees) Keep your weight forward and slowly move your body weight forward through your arms. Keep lowering your hips until you can no longer stay stable. If you experience pain in your back, you've gone too far. Only go as far as your core can withstand. Work on going further each time you do it.
Pro Tip: Think about moving your hips forward, not your arms. Hold your breath on the way down and release when you're back up.