Double-Under
Primary muscles: Calves · Forearms · Core · Cardiorespiratory system
Overview
The double-under is a skill in which the rope passes under the feet twice during a single jump. Unlike a plain jump, it is a timing skill that requires precisely syncing the rope's rotation speed with the body's rhythm, and a metabolic conditioning exercise that tests cardiorespiratory capacity to the limit.
The key to the double-under is not the jump but the speed of the rope. Increasing wrist rotation speed so the rope can pass twice quickly takes priority over jumping higher. Many beginners make the mistake of jumping high and end up making the double-under harder.
A correct double-under posture keeps the body in a straight line. Kicking the feet back ("donkey kick"), bending the knees excessively, and bending forward at the waist are all faulty patterns. These compensations are also why double-unders don't link together consecutively.
Hold the rope handles comfortably, but loosely enough that the wrists can move freely. Keeping the elbows fixed at the sides and rotating only the wrists is the key to efficient energy use.
In CrossFit, double-unders appear in many WODs, including "Annie" (double-unders and sit-ups, 50-40-30-20-10). Advanced athletes can perform 100 or more per minute, at which point heart rate reaches over 90% of maximum.
Step-by-step
Grip and posture
Hold the handles comfortably, keep the elbows at the sides, and stand tall.
Start with single-unders
Find your rhythm first with regular jump rope.
Accelerate the wrists
At the peak of the jump, rotate the wrists quickly twice so the rope passes twice.
Land and rebound
Land softly on the balls of the feet and link immediately into the next jump.
Continuous rhythm
Match breathing to rhythm and keep the double-unders going.
Technical Standards
The rope passes under the feet twice per jump
Keep the body in a straight line (no kicking the feet or over-bending the knees)
Keep the elbows fixed at the sides and turn the rope with the wrists only
Land on the ball of the foot to minimize rebound
Minimize jump height and maximize rope rotation speed
Sync rhythm and breathing
Common Faults
Donkey kick: kicking both feet back as you jump, leaning the body forward
Overusing the arms: turning the rope with the whole arm causes fast fatigue and breaks the rhythm
Jumping too high: mistaking it for a jump problem rather than a rope-speed problem, wasting energy
Landing on the heels: landing on the heels spikes calf fatigue and breaks rhythm
Scaling
Single-unders × 3 — substitute 3 single-unders for each double-under. Or practice a single-double pattern, alternating one single-under with each double-under attempt.
Power jumps + separate wrist drills — first learn the jump rhythm without a rope, and separately practice drills that spin the rope fast with the wrists only.
Triple-under — an advanced skill where the rope passes three times per jump, requiring far more focus and timing than the double-under.
WODs featuring this movement
Annie
Sub-8 min (Elite), Under 12 min (Competitive), Under 18 min (Recreational)
24.3
AMRAP 20 min (score: completed reps)
23.3
For Time (12-min cap)
20.2
AMRAP 20 min (score: completed reps)
19.2
AMRAP 8 min (score: completed reps)
18.3
AMRAP 14 min (score: completed reps)
17.5
AMRAP 40 min (score: completed reps)
14.1
10-minute AMRAP
11.1
10-minute AMRAP - 10+ rounds (Elite)