“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 1 of 3: The Cord
I’m constantly surrounded by competitive jumpers. My business partner, Molly Metz, is a 5-Time World Jump Rope Champion, and the entire JumpNRope staff is composed of champions as well. Our company conducts trainings on double-unders and speed-step jumping— trainings at which we are privileged to meet hundreds of CrossFit jumpers ranging in skill level from “Never got a double under” to “I’m training to be on ESPN”. If there is one constant across the entire range of skill levels that each jumper looks for in a jump rope, that constant is comfort; every last jumper chooses a jump rope that feels just right to them, no matter how different it may be from others’.
From a high-level view, there really aren’t that many differences between jump ropes, you may think—‘so long as the rope isn’t too long or too heavy, it’s probably going to work well for me’. This mentality is wrong. There are several variables that factor strongly into the design of a jump rope- each with its own purpose. Let's start with the jump rope's cord. The four main variables that one can adjust are the cord's (1) length, (2) thickness, (3) stiffness, and (4) weight (or more accurately weight per length). However, since we are discussing the type of cord to use, let's not consider the length for the time being. I'll cover sizing a rope in a later discussion (Part 2 of 3: The Size). This leaves only thickness, stiffness, and weight.
The stiffness of a jump rope’s cord is a measure of the cord's ability to adapt to changes - more flexible, means more adaptive. Note: here I’m speaking about the flexibility of a cord to bend, not stretch. Finding a cord that bends just enough, but doesn’t stretch is difficult, but achievable (we’ve done it!). Just as there is a large range of athletic skill in jumping rope, so is there a large need for a jump rope to be adaptive. Higher-end athletes have great control of the rope as they jump, as well as good jumping form-- meaning they rarely need the rope to adapt to mistakes and form adjustments on the fly. This means that they tend to like stiffer jump rope cord as it provides repeatability in the jump- small changes don’t change the rope’s shape.
Newcomers to jump rope tend to like cords that are more flexible, as flexible cord can accommodate their mistakes and improving jump rope form. Don't, however, get caught with the notion that flexible cords are ONLY used by beginning jumpers, as there is ALWAYS room for improvement for athletes jumping rope. Additionally, training with heavier, flexible cords can be quite advantageous, as it provides just enough resistance to quick jumping, but allows for enough speed in your step that you’re training with fast feet.
- An example of "stiff" cord is the 1/16" stainless steel cord used in the uncoated and blue-coated R1: Speed Rope. This cord has been championed these past five years by JumpNRope and the competitive jump rope world for speed and power events. Note: the coating on the cord provides a nice barrier to general wear-and-tear.
- An example of “flexible” cord is either the black coated steel cord used in the coated R1: Speed Rope (used heavily in CrossFit and elite athletic training), the PVC cord used in the R2: Trainer Rope (used for training everywhere by everyone- flexible, but not stretchy), or in the beaded cord of the R3: Beaded Rope (used for warming up and strengthening arms).
The weight of a cord is also, without a doubt, a central factor to deciding upon the right jump rope. One might think, in fact, that since a heavy rope is more difficult to throw around that, conversely, a lighter rope is always better. Well, lighter is NOT always better. Imagine the case in which you jump with a near-weightless rope. It would be quite difficult to judge by feel whether you should jump or not— you wouldn't really know where the rope is in relation to your bounding body—weight helps the user gauge the rope’s location. Additionally, a super-light rope is much less controllable— just a small amount of flicking of the wrist will propel the cord around your body wildly. Therefore, there's a trade-off between a light rope and a heavy rope: fast & hard-to-control or slower & stable. Finding that balance in weight is a jumper's preference. A skilled jumper with experience will likely choose a lighter rope, because they have the rhythm of jumping under control, while a beginning jumper will be much better off with a slightly heavier, more stable rope.
Combine this analysis with what we've learned from the stiffness of the cord, and we find that a great beginning jumper will likely find success in a slightly heavier cord, with plenty of flexibility, while the more-experienced jumper will prefer either a semi-flexible stainless steel cord or a flexible coated steel.
- The R1: Speed Rope features either the semi-flexible steel cord or a flexible coated steel cord. Both ropes are super-fast (used by World Champion jumpers!) and should be considered ‘competition ropes’ to work towards.
- The R2: Trainer Rope, which features the flexible PVC cord, is slightly heavier than a thin steel cord, and provides a nice stable jump rope for beginners, or a nice fast-paced resistance for higher-end athletes.
- For a great arm burnout or overall athletic warmup, the R3: Beaded Rope provides weight via 60 colored beads, and is great for a very stable jumping experience.
In Part 2 of this 3 part series, I will discuss the two variables of the jump rope's cord that we haven't discussed- the thickness and the length. This discussion will focus on both the aerodynamics of the cord, along with how to become an efficient jumper by playing with the rope’s length.
...for more information on the different types of jump ropes available, please visit the JumpNRope Jump Rope Selection Guide webpage.