Isometric Core Strength: Forearm Plank Into A 5 Second Isometric Knuckle Pushup Midway Hold.

Johnny Grube doing a tough Isometric type of pushup from the forearm plank position.

Start from a forearm plank, from there bring each arm to a pushup position WITHOUT twisting the torso, than lower mid way and
hold for 5 seconds and repeat.

Don't do another until you are set in the forearm plank, you want as little movement in the core.

Try 10 of these.

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