“What Makes a Jump Rope Just Right?”
John Obrecht, Ph.D.
Vice President – JumpNRope, Ltd.
In this three-part series Dr. Obrecht explains what makes a jump rope just right from the scientific perspective of a Ph.D. Physicist. In Part 1 of 3: The Cord, we learn about the variety of jump rope cords, and how careful selection can lead us to a better jumping experience. In Part 2 of 3: The Size, we learn about how to become efficient in jumping by choosing the proper cord size. Finally, in Part 3 of 3: The Handle, we learn about the most important part of the jump rope, namely the handle technology that makes your rope turn efficiently.
- Dr. Obrecht did his Ph.D. work in Atomic Physics at the University of Colorado at Boulder with Nobel Laureatte Eric Cornell. He is currently the Vice President of JumpNRope, Ltd.
Part 2 of 3: The Size
In part 1 of this 3 part series, I discussed the different variables of a jump rope's design and I outlined the key points that one should look for in a jump rope's cord, namely the cord's weight and flexibility. In this part of the series, however, I will focus more on efficiency in jumping, and how to reach a level of jumping at which double-unders become a breeze.
Let's now look at the thickness of the cord. Most jumpers are not going to truly notice the thickness of the jump rope's cord unless they’re performing jump rope with high-intensity. They may notice the fact that thicker ropes are typically heavier than thinner ropes, but you generally won't notice the aerodynamic drag created by the thickness of the cord. A good rule of thumb is this: unless you can hear the whistling noise created by the speed of the cord, you're likely not bumping up against aerodynamic drag as your main challenge in jumping. Therefore most of us aren't going to need to factor the aerodynamic cross section of a jump rope cord into our decision-making process when selecting an appropriate rope.
Others, however, like those competing in the CrossFit Games or the World Rope Skipping Championship, are going to be selective with the thickness of the cord. In the case of reducing aerodynamic drag, thinner is always better, obviously. What can end up becoming an issue with thinner cords, however, is the durability of the cord, as thinner cords will tend to have a higher risk of bending, breaking, fraying, or any other casualty of jumping rope. There's a simple trade-off that comes along with a lower-profile cord, and finding that can be challenging.
- An example of a durable, low-profile cord is the blue-coated and uncoated stainless steel cord of the R1 Speed Rope. This rope is used by the fastest jumpers in the world!
- The absolute fastest jumpers in the world use a very special, lightweight steel cord for speed events. Though not recommended for the general public, JumpNRope supplies these jumpers with these custom-made R1: Speed Ropes!
Along the lines of efficiency in jumping, comes a discussion on the length of the jump rope’s cord. When it comes to a jump rope's length, shorter is typically better, up until that point at which you can't jump it comfortably anymore. Short ropes are efficient, as you don't have as much cord to throw around (weight), and the cord you do throw around doesn't travel far from the axis of rotation (the centrifugal force that your arms work against).
Efficient jumping comes then from small movements of the wrists and feet controlling a relatively small rope (small being relative to the user’s size). It may happen from time to time, however, that fatigue has set into your body and your arms aren’t able to control the rope the way that they do when they are fresh. This is why it is important to be able to adjust the length of your rope (at least a small amount). Adjustment can come from either tying a knot in your cord (if it is flexible- like PVC), or moving a sizing collar up or down along your steel cord. The ability to change the rope’s length to adjust for your fatigue level is important to consider in choosing your just right rope. If you plan to be using your arms a lot in a workout, make sure you allow for a few inches of room in your jump rope’s cord!
Putting this all together, the key thing to look for in the dimensions your jump rope’s cord are (1) short, yet comfortable, length, with (2) a thickness of the cord that is commensurate with your skill level—thin profile for skilled jumpers, and (3) the ability to adjust the length of your cord at a moment’s notice!
In Part 3 of this 3 part series, I will be discussing the most critical part to your jump rope’s design, the handle. A properly-designed handle will facilitate easy jumping and allow for an effortless turn.
...for more information on the different types of jump ropes available, please visit the JumpNRope Jump Rope Selection Guide webpage.