Double-Unders: Friend or Foe?

Posted: April 20, 2012 in Uncategorized

Double-unders are commonly the first nemesis of every new CrossFitter; though they often don’t realize it until they have been sucked into the realms of CrossFit, from which no one leaves. The trainers don’t over-emphasize the rx’d double-under, and instead happily provide modifications of 2 for 1, 3 for 1, and even 4 to 1 singles for every prescribed double. The pressure to rX usually comes from within when we get sick of doing extra jumps, and we see what effect it is having on our times. We are intrinsically forced to start practicing but how and where do we start. What kind of rope should we use? How long should it be? How high should we jump? How do we increase our rope speed, and what should the cadence be? These are some of the questions that are commonly asked singularly but without the answers to all of them collectively, we can’t effectively string together a substantial run of double under repetitions.

For me, the process was a long one. Maybe it was because I am very analytical when it comes to movement and I wanted to understand every intricacy. Maybe it was due to the fact that I was looking in a hundred different places for any information or instruction. Or maybe it was due simply to the incoordination that is inherently part of learning a new skill. I will attempt to articulate how the process was for me so as to assist anyone who is struggling and would like to forego any plantar fascia, foot and calf pain, shin splints, or any other side effect of the dreaded double under. First we will examine some of the common mistakes that people make, followed by some tips, modifications, and progressions.

Because CrossFit is multi-dimensional, athletes are forced to learn to use their balance, strength, and flexibility differently for the imposed demands of different exercises. For example, the variations of the squat teach us to keep our weight in the heels; but for plyometric exercises like box jumps and double-unders, the heels should make minimal, if any, contact with the floor during reps.

Our muscles contract and relax in many ways to produce and slow movement. One quality is that muscles have a “spring-like” quality so as we are coming down from a jump, there is an increasing energy potential that will assist greater force in the opposite direction. Think about how a spring works; the more compressed a spring becomes the more potential energy there is to generate force in the opposite direction. Imagine a pogo stick without a spring, or a trampoline that is only 6 inches above the ground; all momentum would be lost and wasted. The same principle can be applied to the double-under if we are coming down flat footed each repetition. This type of jumping pattern is not musculo-skeletally efficient and can potentially increase the risk of joint problems and stress fractures because instead of the muscles using the force and momentum for movement, that energy is lost and the impact is transferred into the bones and joints of the legs. That is kind of a long and drawn-out way to simply say Stay on the Balls of your feet!

Another movement inefficiency or mistake has to do with the jump itself. Jumping should be a smooth movement without any locking or jarring, and very little flexion (bending) at the knees or hips. When people are starting out, they will do whatever it take to get high enough for two rope revolutions per jump. The most common jumping “techniques” are bending the knees to 90 degrees and the pike jump where the knees are straight but the hips are flexed and come forward so the body is bent at the waist. There are a few flaws in jumping this way. First, both are very inefficient and will cause fatigue very quickly. Second, the chance of injury is much greater; maybe not immediately, but over time and hundreds of repetitions, the constant force of landing from inefficient jumping will eventually cause joint and connective tissue injury. Lastly the idea that jumping higher will make the double-under easier is inherently flawed. This was an epiphany to me as I watched the Games Athletes; none of them were jumping any higher than they would on single jumping. Learning the double under has less to do with the height of the jump and more to do with rope position, speed, and cadence.

Another common problem with jumping is the speed of the jumping in relationship to the exercise. Most people, when trying to learn the skill, naturally speed up there jump as the increase the speed of the rope. Athletes will get the hang of the skill much faster if they consciously focus on slowing their jump down.

Now we will move to the most common mistakes athletes make with the revolution of the rope. We will first examine the speed and cadence, and finally the placement and movement of the arms, wrists, and hands.

When starting out, most athletes think that the rope cadence is an even-beat cadence like in singles, only twice as fast. This is not the case, at least for me. It’s hard to describe a cadence in words without the aid of sound effects or clapping etc. The best way I can describe the syncopated rhythm is by comparing it to a heart-beat. Each beat of the heart, if broken down, is two separate, but fast and consecutive beats. The double under is the same for me. I like to do two quick rotations in a row broken up by a very brief pause, rather than just a double-time, even cadence.

The arm position plays perhaps the most important role in finding your double-unders. The rope needs to short enough that there isn’t any lag in the rope to maintain speed, but long enough that it’s not getting tripped up at the feet. Too many times we blame the rope length when more often the culprit is our arm position. The wider we position our arms, the shorter the rope becomes and higher we have to jump. The same can be said if our arms are too far forward or back as well. The best way to avoid shortening your rope with your arms is to position the elbows so that they are just outside of contact with the side of your body.

I have recently seen and read about how the “sling-shot” bench press training aide, can be modified and used for several other exercises as well. In addition to “pushing” exercises, the sling-shot can be used to assist an athlete in keeping their elbows in and forward to help build muscle memory for the double under. If you don’t have a sling-shot, you can also use a power band, belt, etc to stabilize the upper arm and prevent the arms from moving back and out.

The fact that the elbows should remain close to the body shows us that the shoulders are not generating the movement of the rope. Instead, the speed of the rope’s revolution should be generated through the pronation (inward twisting) of the forearm, and circumduction of the wrist, both at high frequency.

As this is a new skill for many, all of the items discussed above can be a little overwhelming to consciously focus on all simultaneously, so I have broken down the skill and into steps that I used when learning.

  1. Rope Length – Standing on the center of the rope with one foot, the end of the cable should be close to the chest/arm-pit level.
  2. Start with Singles- Forget about any other way you may have jumped rope in the past (double jumps for every rope revolution, forward/back single leg jumping etc.) Jump in place using only minimal flexion at the knees and hips. Hold your elbows close to the body and use the forearms and wrists. Watch yourself in the mirror to make sure that you are not excessively bending your knees and hips.
  3. Speed up you Singles- After you feel comfortable with singles at a slow pace, speed up progressively to the point that you are going as fast as you can jump with only jumping 2 or less inches per repetition. Note that in order to reach top speed, you must maintain the proper technique discussed above. When you have solid form fast singles go to the next step.
  4. Transition into doubles- Start slow. Perform 4 singles and one double and repeat. When you can maintain this pattern unbroken, do 3 singles to 1 double. Follow this pattern until you work up to consecutive double-unders.
  5. Have someone watch you. Tell them to watch your knees, hips, and shoulders. They may be able to help pinpoint what is sabotaging your efforts.
  1. Gwen says:

    You mention shin splints and plantar fascia. I successfully did double unders for my first 2.5 years of crossfit, but in year 3 developed both of these problems, mostly on one side. I am trying to figure out what’s going wrong. Something with my form? Or maybe my footwear? I wear Innov-8 F-lite 230s. Thanks for your thoughts.

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