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Advanced Core Stability: One Arm RKC Plank

I love the RKC plank ever since learning about it several months ago from my friend Bret Contreras. It's simple to teach, difficult to perform and satisfying in the feel of whole body muscular activation you get with it.  It's one of the only "floor" exercises that gives you the sensation of intense whole body contraction similar to gymnastics open chan movements such as the planche.  As opposed to a regular plank, where whole body tension is often times not very significant and can be held for prolonged periods, an RKC plank relies on developing large amounts of whole body tension and susequent  neuromuscular "irridation", where the whole muscular system becomes a tightly wound spring.

 

 

Credit obvilously goes to Pavel Tatsouline for the genesis of this exercise, which takes a traditional plank and adds "muscle" to it via increased lattissimus, quadriceps, and gluteal contraction.  By doing this, the abdominals are forced to contract more intensly than in a standard plank, with the net effect of increased dynamic stiffness and "pillar stability" around the lumbar spine.  I believe the magic in a properly performed RKC plank is in it's "anti lumbar extension function"- where the force couple of the quadriceps, abdominals and gluteals, along with added isometric tensioning of the latissimus/thoracolumbar fascia really lock down the lumbar spine in an appropriate fashion.  Creating dynamic stiffness and strength in this position transfers nicely to activities on two feet in strength or regular sport.

As I was progressing myself as well as my clients and teams through this exercise, I thought of how I could make a hard exercise even harder.  Not just for the sake of making it harder arbitrarily, but to add another musculoskeletal and performance challenge to the activity; in this case to resist lumbopelvic and trunk rotation.

 

Enter The One Arm RKC Plank

The One Arm RKC plank is a great progression for an already tough exercise.  By removing the support of an arm, you now require your stabilizing musculature of the trunk (internal/external obliques, quadratus lumborum) to work extremely hard to resist falling into rotation.  The natural inclination is to elevate the pelvis to counter the trunk rotation; this is what we are trying to avoid.

Additionally, you will notice a significant overflow of muscular activity of your triceps, as your forearm and fist is the only upper extremity contact with the ground at this point.  In addition, the latissimus fires extremely hard, leading to "tenting" of the thoracolumbar fascia, which further lends to additional lumbar stabilization.

You will find that the quadriceps, gluteals and abdoninals contract even harder than in a traditional RKC plank as a result of the induced instability. This is involuntarily if performed correctly, and another example of "self limiting" exercise. 

 

Setting Up

The one arm RKC plank is performed by first setting up into a traditional two arm plank, then contracting the quadriceps as well as the glutes (into posterior pelvic tilt), which leads to increased abdominal contraction.  When these muscles are set, then "pull" your elbows to your feet isometrically while at the same time isometrically "pull" your toes (your foot contact in the plank position) toward your elbows.  What you will feel is a boatload of whole body tension that we will use to our advantage soon.

Now, while continuing to hold the tension, slowly and deliberately remove one of your forearms from the floor placing your hand palm up in the "small" of your back.This requires an even further intense contraction of the support arm, and can be facilitated by pushing your support elbow and fist into the floor. Intent is everything here-push hard! 

At the same time, you will feel gravity trying to pull your pelvis down on the unsupported side.  This is normal and expected.  To counter this, focus on bracing  your quadriceps and gluteals even tighter on the unsupported side, as well as focusing on keeping a neutral spine position and not allowing your hips to "pike".  At this point, the intensity of whole body muscular contraction increases even further as you fight to keep your trunk and hips parallel to the ground.  This is the crux of the exercise:  Whole body tension from the supporting forearm through the toes, while working hard to keep your pelvis and trunk level.

The video below outlines what you should be striving for in the performance of this exercise:

 

 

 Here is an alternate view of the transverse plane from "top down", again avoiding pelvic and /or trunk hiking:

 

 

Program Placement, Sets and Time

This exercise can be flexible in terms of program placement.  It fits nicely in a warm up/ movement prep, between sets of your main exercises, or at the end of a session.  I have utilized it as a facilatory activity with sprinting and plyometrics, sandwiching a set or two between repetitions as a "potentiation" primer. 

In terms of sets, 4 to 8 sets, lasting from 6-15 seconds/set is a good place to start.  Obviously, you will do an equal number of repetitions on each side, although you will more than likely have a more dominant side with better perfoormance, so adjust set times accordingly.  At least 1-2 minutes rest between repetitions should be taken; more rest may be needed if technical performance suffers.  Of course, technical failure is the end point for this exercise; learning to judge this is important as well.