The traditional front plank is one of the most popular exercise movements for developing core strength. In this exercise the lifter lies with their toes and forearms on the ground and tries to maintain a straight and locked out position in an isometric hold for as long as possible. The problem with this movement is that the only way to progress the intensity of the exercise is by continuing to hold a plank for longer and longer. Once the plank exceeds roughly 10 seconds in duration the exercise becomes more of an aerobic endurance type movement rather than a strength movement. Furthermore, the traditional plank fails to fully activate the deep abdominal wall (1), thus failing as a complete core strengthening movement. As Professor Stuart McGill said with regards to traditional planks for time: “there is no point to this kind of activity other than claiming a record.” (2)
Instead of traditional planks, try using the RKC plank to strengthen the core. RKC (Russian Kettlebell Club) planks involve brief periods of maximal exertion followed by brief to moderate periods of recovery, allowing individuals to achieve greater core activation and strength. To set up the RKC plank, angle the forearms at approximately 45 degrees to one another with the elbows slightly higher than the shoulders on the floor. During this plank the lifter will retract and depress their shoulders, trying to pull the floor back towards them with their arms. The glutes will contract trying to bring the toes further towards the body center and pulling the pelvis into posterior rotation. The goal in this movement is to intentionally contract the abdominal walls as hard as possible while bringing the arms and toes closer to the body midline (they won’t actually move far as they are fixed to the ground, but this type of movement is the intent). This maximal contraction should last between 5-10 seconds and can be followed by a period of complete rest or by the less intense traditional plank.
The advantages of the RKC plan are that this type of plank fully activates and engages all of the core musculature, plus the shoulders and glutes as a bonus. Where a traditional plank for extended periods of time is an aerobic exercise, the RKC plank is short in duration and trains for true strength rather than endurance.
Personally, I program my clients to do 1 to 1.5 minutes of 5 seconds of maximal effort RKC plank followed immediately by 5 seconds of rest in the traditional plank for 3 sets.
For a better understanding of how the RKC Plank is performed, please refer to the video.
Dr. John Rusin. The Best Exercise You Aren’t Doing: RKC Plank. Drjohnrusin.com.
Rosie Fitzmaurice. Business Insider, March 24, 2018.