With both the pike and straddle variations focus on keeping your legs straight and fully engaged from your hip out to your toes. This is a pulsing motion and your heel should hover above the floor in the bottom traveling just a few inches above that each rep.
Keep a light fingertip touch to the floor rather than pressing your palm into the ground. The further you walk your hands forward the more challenging it will be. The closer you keep your hands to your hips the less challenging it will be. Start with your hands by your hips if you are not sure and then inch your fingertips forward.
These are incredibly effective for developing strength and stability for a solid trunk and anterior chain.
