If you've ever taken a CrossFit class or have done similar HIIT workouts, then you're no stranger to seeing double unders. Double unders are exactly what the name implies: The jump rope passes under your feet twice before you land.
"[Double unders are] definitely an advanced skill, but once you're able to do them you'll be able to unlock another level of fitness," Dan Witmer, co-founder of Jump Rope Dudes, an online jump rope fitness community, tells LIVESTRONG.com.
But don't let this complex skill intimidate you from taking a swing at things. Not sure where to start? The first step is to scale it down. Once you become a pro with single unders and basic jumps, you'll be able to add double unders easily into your workout routine.
We tapped trainers to break down how to do double unders correctly. Plus, we offer three exercises that'll help you get more out of this advanced move.
The Benefits of Double Unders
As a jump rope workout, double unders can improve your cardiovascular fitness, torch tons of calories (372 calories in 30 minutes for a 155-pound person, according to Harvard Health) and build lower-body endurance.
In order to nail the move, you have to jump both higher and faster than a standard skip, which spikes your heart rate in a flash. So don't be surprised if you feel breathless after just a few reps.
"It's almost like when you're running and you go into a sprint," explains Amanda Kloots, a fitness trainer who teaches jump rope classes in Los Angeles, California.
If weight loss is your goal, the intensity of double unders makes them a valuable metabolism-boosting addition to any workout. "Because it's such a strenuous movement, it requires you to recruit more muscles, which burns more calories," Witmer says.
And because double unders feel like a sprint, you don't have to squeeze in dozens of reps to feel like you got a tough workout. "It's a great tool for giving you a more efficient workout," Witmer adds.
Double unders are also fantastic for improving balance and hand-eye coordination. Once you try double unders for the first time, you'll see why: You have to time your jump with the double pass of the jump rope just right in order to complete the move.
How to Do Double Unders Correctly
If you're used to standard single- or double-leg jump rope skips, double unders will feel pretty awkward at first, as it's usually the timing that trips people up. "Obviously, anyone can do [double unders], I truly believe that," Witmer says, "but in order to get there, the biggest thing is timing."
You not only have to move the jump rope fast in order to get it under your feet twice, but you also have to jump high enough to give the rope enough time to get under your feet twice before they have a chance to land.
But don't worry, with a little practice — and patience — you'll be a double-unders pro in no time. If you're comfortable with the basic single- and double-leg skip, you're ready to master double unders.
Just keep in mind that double unders are pretty strenuous. If you try to do them every day as a beginner, you'll likely develop shin splints, aka acute pain in the shin and lower leg, Witmer warns.
Limit your double-unders sessions to two to three times per week, aiming to get 10 to 20 double unders per session, if you can. You'll be able to add reps and sessions as you get stronger.
1. Practice Without a Rope
Both Kloots and Witmer believe that the most effective drill for learning double unders is the bodyweight version, or double unders with an invisible jump rope. Here's how to do it:
- Set your jump rope aside but jump as though you still had one in your hands.
- Holding the ends of the jump rope in each hand, keep a natural bend in your elbows and keep them close to your body. Wrists are jutting out from the sides of your hips.
- Move the imaginary jump rope with your wrists (and only your wrists) and stay on your toes, keeping a soft bend in the knees.
- Count out single-under reps aloud, or in your head, jumping with you feet hip-width apart.
- When you reach your fifth rep, jump higher — about six to eight inches off the ground.
- As you jump, whip the imaginary rope once very quickly with your wrists. After swinging the rope hard once, allow the momentum to carry it around twice.
- Reset if you need to, or continue with single-under reps. Again, when you reach the fifth rep, practice doing another double under. Continue practicing the rhythm until you're ready to try it with a jump rope.
Don’t make the mistake of trying to swing the rope twice — swing it hard once and allow the momentum carry it around twice. “If you try to spin it around twice, it makes the rope really loose and throws it out of its inertia,” Witmer explains.
2. Keep Elbows Straight and Arms Light
A common mistake among beginners is bending sharply at the elbows and tensing the arms, Jereme Schumacher, CrossFit Level 1-certified physical therapist at Bespoke Trearments in San Diego, California, tells LIVESTRONG.com.
"Bending your elbows decreases your ability to generate torque on the handle, so make sure to keep your elbows relatively straight, which will allow the rope to spin faster," Schumacher says.
At the same time, you don't want your arms to tense up, either. Keep your arms relaxed with a natural bend in the elbows. In addition, you want to maintain a relaxed grip on the handles to ensure that your hands — not your arms — are doing the work, Schumacher says.
3. Keep Your Core Tight
Whether you're performing doing a double-under workout or just jumping rope for fun, you want to keep your core tight throughout the movement, Schumacher says.
Your posture plays a big role in nailing the double under, so avoid hunching forward and allow the rope to clear. Keeping your core braced throughout the movement will also help keep your back flat and shoulders back and away from your ears.
4. Alternate Single and Double Unders
As you begin experimenting with the rope, Kloots suggests practicing intervals, where you alternate regular jumps with double unders. Try this sequence:
- Perform 10 single unders.
- Then, attempt one double under and stop to reset.
- Repeat until you're able to complete a full double under on each attempt.
- Gradually decrease the number of regular jumps before each double under.
Once you feel confident, eliminate the breaks in between sequences. Do a couple of regular skips, perform a double under and then go right back into the regular skips without stopping to reset.
Learning the rhythm of the exercise is the hardest part, but when you get over that hurdle, double unders will feel natural. "Once you find the rhythm, it's like riding a bike," Kloots says. "You'll find it never leaves you."
5. Above All, Stay Relaxed
When you see a boxer or CrossFit athlete perform double unders, they seem effortless — and that's how they should feel.
"Double unders can get frustrating when you are starting off, but this will just cause poor rhythm," Schumacher says. "If you get frustrated, just take a deep breath, and try to stay relaxed while you are jumping," he says.
3 Double Unders Exercises
As you learn the double-under rope movement, there are a few exercises you can practice to help you get a better feel for the motion. If you're still struggling to get a good rhythm, Schumacher recommends these three exercises.
Move 1: Hollow Hold
- Lie face-up on a mat or the floor with your legs extended in front of you, arms extended overhead and elbows by your ears.
- Keeping your low back rooted into the ground, lift your shoulder blades, arms and head off the floor.
- At the same time, raise your legs up, hovering just above the floor, drawing your belly button into your spine.
- Hold this position for 30 seconds before lying back down to the starting position.
"Think about making your body the shape of a banana, and you should be balancing only on one point on your lower back," Schumacher says. This is the shape you want to make while doing double unders.
Move 2: Single-Under Jumps
- Start standing tall with your arms relaxed at your sides, one handle in each hand.
- Spin the rope over your body and jump once over.
- Keep the momentum going, repeating single jumps.
Single-under jumps are a great way to build wrist, calf and core endurance, which is needed for double unders. Try varying the speed of your single-under jumps to get comfortable with rope speed and rhythm.
Move 3: Penguin Jumps
- Start standing tall with your arms relaxed at your sides, one handle in each hand.
- Jump at a consistent pace, as if you were performing single unders with a rope.
- Once you have a consistent jumping rhythm, tap your hands against your thighs while in the air.
- Create a "jump, tap, tap" rhythm as you jump.