Undersun Fitness

- 5 March

Resistance bands are the most practical, cost-efficient, and effective equipment for building muscle and getting stronger anytime, anywhere – and Undersun Fitness is leading the charge in this area. 

Where cardio is concerned, no piece of equipment is more practical, cost-efficient, and effective than a jump rope. It’s the perfect complement to training with resistance bands. So it was only natural that we would add this tool to our arsenal… via the Undersun Jump Rope.   

Undersun Jump Rope Description

The Undersun Jump Rope was born from an all-too-common disdain for long, boring cardio sessions. You know that dreadful feeling: You’re going through a tough workout, knowing all along that you have a full cardio session to do after your resistance training. That’s how a 30-minute workout turns into an hour-long session, or an hour into an hour-and-a-half. 

“I’ve always incorporated jump rope into my own workout routines, and a lot of the reason was that I hated doing cardio,” says Undersun Fitness owner and founder James Grage. “The idea of doing resistance training for an hour or more, only to add on an extra 30 minutes of cardio, was never appealing to me. I always thought cardio was pretty boring, but I don’t like the idea of wasting time standing around between sets.”

What James is talking about is doing cardio during your workout, not after, by jumping rope between sets of resistance training. All those 30-60-second rest periods normally spent inactive now become cardio intervals that burn extra calories and body fat and improve conditioning. And guess what? Your 30-minute workout is still only 30 minutes (or 45 or 60 minutes), yet you’ve done both resistance training and cardio in that time.

“Jumping rope between sets is a great way to keep the heart rate elevated through your whole workout,” says James. “So that’s one of the ways I’m able to get around having to put extra time into doing cardio, and that was also my reason for coming out with the Undersun Jump Rope.”

Jumping Rope for Cardiovascular Fitness

One great thing about jumping rope is that it can be done with varying intensity, which makes it a useful cardio tool for people of all fitness levels. 

“Me and Annik both incorporate jumping rope into a lot of HIIT [high-intensity interval-training] workouts,” James says, referencing Undersun Fitness co-owner and lead trainer of the TA2 Bodyshock program, Annik Nayler. “Because even though you get your heart rate up with the jump rope, you can also control your heart rate. Jumping rope in itself isn’t always high intensity exercise.”

“For example, I may do, say, 30-60 seconds of a high-intensity exercise like burpees, getting the heart rate elevated, and then jump rope for 60 seconds to bring the heart rate back down,” says Annik. “Or I’ll do a resistance-training exercise, like bicep curls, and then turn around and do the jump rope for a minute.” 

Undersun Jump Rope Key Features

High-Quality Aluminum Handles – “Of all the jump ropes I’ve ever had, the ones I really liked always had really nice handles, and the ones I hated always had cheap handles,” says Grage. “So for the Undersun Jump Rope, we wanted something with a really nice, durable handle, but also something that had a good feel and a little bit of weight to it. That’s why we ended up going with this aluminum handle with a knurled grip. It almost has the feeling of a barbell.”

Adjustable Length – The “rope” portion is a strong but durable 5mm PVC cord, and it comes intentionally long (118 inches, nearly 10 feet) with the ability to easily adjust the length. “You can keep some extra length on there,” says Grage, “but you can always shorten it as you go. A lot of jump ropes have the adjustment inside the handle, so you actually cut the rope and tie it in a knot so that it’s hidden in the handle. We wanted one where you had an external adjustment, so that’s why there’s the two eyelets at the end of each handle. That way, you can feed the rope through one, then the other, to quickly and easily adjust the length of it.”  

(See below for instructions on how to adjust the length of your Undersun Jump Rope, plus the embedded video in this article.)

Convenient Carry Bag – The Undersun Jump Rope comes with its own small black nylon bag. This makes it easy to stow away in a backpack, drawer, closet, or car without it getting tangled with other items.  

Aesthetic Design – Not only is it functional, but the Undersun Jump Rope looks great as well. The cord is classic Undersun orange, and the handles have the brand’s sun logo printed on. 

User Tip: To get the maximum life out of your rope, we recommend jumping on a smooth surface, like a rubber matting or gym floor. If you jump rope on rough concrete surfaces or anything with rough edges, you’ll prematurely wear out your rope. This is the case with any jump rope.

Get Your Undersun Jump Rope Here!

How to Adjust Your Undersun Jump Rope to Proper Length

By James Grage


Determining the right length of jump rope to accommodate your size and fitness level is an important yet often overlooked detail. 


When you’re a beginner, you want your rope length on the longer side. Most beginners hold their hands out a little wider from the body. As you get better at jumping rope, you’ll want to start shortening the length of rope and holding it tighter to your body. This makes the movement more efficient and allows you to jump faster.  

To determine exactly how long your jump rope should be, use one of these two simple methods:

(1) Add 3 feet to your height – If you’re 6-feet tall, go with a rope length of 9 feet. If you’re 5’5”, the rope length would 8’5”. Keep in mind, this does NOT include the handles. Don’t use the handle itself as part of your measurement. Just one end of the rope to the other. 

(2) Step on the Rope – Holding your jump rope, a handle in each hand, step on the center point of the cord with one foot, and pull the handles up toward your sternum (breastbone). The lower ends of the handles (where the rope attaches) should come right up to your sternum. If the ends come up significantly higher than that, adjust the cord to make it shorter. If below, let out some cord to lengthen it. (In the video included in this article, I show you how to adjust cord length on the handles.)