Nicholas DiNubile in his Framework book series uses two planks as measures of core stability. He rates people using the scale of RED, YELLOW, and GREEN. This is what he says a would earn a green score:
Prone Plank: all these done with no rest: prone plank 60 seconds then lift right arm holding it by your hip for 15 seconds supporting your body weight on your left forearm and both feet. Repeat lifting your left arm. Then with both forearms on ground lift your right leg up and hold 15 seconds. Repeat with your left leg. Next lift your right arm and left leg simultaneously and hold for 15 seconds. Repeat with your left arm and right leg. Then return to the plank position and hold for another 30 seconds. If you can do all positions in a row for full time you earn a green score.
He uses a side plank on your elbow to measure lateral strength and to earn a green score you have to hold each side for 3 minutes without sagging.
I use these quite a bit to test clients strength and give them a goal to build towards. I make sure that clients are not in thoracic flexion during both of these and I cue them to keep their shoulder blades together (which puts them in a much better position and makes it harder for most people who are used to doing everything in flexion).
Let me know what you think after you try it.
Matt Whitehead – Oregon Exercise Therapy