Does anyone know about any credible plank fitness standards?

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

Hi Jim,

You can just test your clients on the plank and then retest them after few weeks to see if they were able to hold it longer than the first time. Based on their time you can train them accordingly. At least this is what I do (I like it simple).

Best,
Harris

Planks are a great way to assess many factors
I time my clients as soon as I think they are ready to hold proper form and re do the test 4 weeks later.

Be your own credible source as everyone is different!