This is a great way to really ramp up the intensity of your everyday plank for both your beginner clients, as well as some of your more advanced clients. You do not need to hold it for obscene amounts of time if you do it right so the RKC plank not only makes your workout more intense, it also helps keep the time shorter.
For your beginners, have them get into a strong plank position from their knees and elbows. Now from this position have them keep their body still and have them pull their elbows down towards their navel building as much tension as possible. Again, their body should not move, they are trying to build up maximal tension in the core. To make this version a little harder you can always have them start with their elbows further out in front of them. So instead of starting with the elbows underneath their shoulders, have them start with the elbows underneath their chin.
Now lets take the everyday plank and put it on steroids. That is how I typically describe the harder progression of this exercise. This version starts out the same as a normal plank, but that is where it ends. You are going to ramp it up by building up a ton of tension. Here are the 4 steps that I teach (in this order):
- Extend your knees and contract your quads as hard as possible, as well as adducting (or bringing your inner thighs towards each other).
- Squeeze your bum cheeks together (to the point that they should actually be externally rotating their hips). **This is the area where they will let go of the pressure first, and most times they don’t realize. Make sure that you cue this throughout the duration of the exercise.
- Pull your elbows down towards you navel.
- Pull your toes up towards you navel.
As I mentioned in the easier version, your body should not move, so if their body shifts up when they pull their elbows down they are doing it wrong. If you see their head (or even their whole body) shaking you know that they are doing it right.
As far as time under tension, I like to start with a 7 second hold followed by a 3 second rest. This allows them to do some quality work, without their form going to crap. Combined with the incomplete rest of 3 seconds you can easily build up to a 60 (technically 63) second set by doing 9 reps. Once they’ve mastered the 9 reps of 7 seconds, you be the judge of whether you want to move it up to 10 seconds or 15 seconds. Heck why not 14 seconds or 17 seconds just to be random! But let me stress one thing here, do not sacrifice perfect form for more time. This exercise changes completely when done at anything under maximal contraction.
Here is my good friend Bret Contreras rocking some sweet plaid shorts while doing some RKC planks!
You don’t necessarily have to do all 4 steps to begin with. When I’m teaching this, I like to slowly increase the complexity, so I’ll start them with only squeezing the quads and bum. Once I’ve seen they have got that then I’ll have them pull down with the elbows, and lastly I’ll have them pull up with the toes. Always remember to progress your clients to the appropriate level, anyone can kill their client, or make them extremely sore. A great trainer knows how to apply the proper dose (which I know is every one of us).
Here is a great video by Bret who I originally learned this exercise from: