Muscles Targeted: Double unders have become extremely popular and they are now being included in many CrossFit WODs (workout of the day). This exercise consists of jumping rope where the rope is passed under the feet twice while the jumper is in the air. It is an excellent aerobic exercise that burns lots of calories in a short amount of time while targeting virtually every major muscle group in the body. The muscles in the legs (quadriceps, glutes, hamstrings, calves) are used to propel the body upward and the core muscles in the abdomen and lower back are used for stability throughout the exercise. Muscles in the arms and shoulders are used throughout the entire range of motion when the jumper is grounded as well as airborne to build and maintain rope speed.
Exercise Instructions: Begin the double unders exercise by holding a jump rope in both hands and stand with your feet slightly less than shoulder width apart. Relax your shoulders and bring the rope around to the front of your body. Swing the jump rope and jump over it several times using a single jump in order to warm-up before starting the double jump technique (double unders). Let your knees flex slightly when you land to absorb some of the impact. Increase the speed of the rope so that it passes under your feet twice on every jump. Keep your abs and butt muscles tight to maintain control of the jumps. Keep your elbows tight to your body, close to the rib cage and generate the rotation of the rope from your wrists. Your jumps should be low and efficient, ideally 2″ to 3″ off the ground. Keep your toes pointed at the ground when you are in the air and land on the balls of your feet. Focus on maintaining the correct form throughout the duration of the exercise.
Things to Avoid: The double under exercise is an easy movement to mess up since it is much more difficult than a traditional single jump that is normally executed when jumping rope. The most common mistake is to try get some extra time in the air by either pulling the knees up or bending at the waist. Neither of these strategies is effective. Keep your body upright, in a straight line, throughout the exercise and focus on moving the jump rope around your body faster with the use of your wrists. The spine and shoulders should be relaxed and neutral. Make sure you use a jump rope that is the right length (not too long or too short). The correct length of a jump rope is when the handles are positioned just below your armpits when you are standing on the rope with one foot. Do not let your feet come together to closely when you are jumping. This will make it harder to maintain your balance and may cause you to jump slightly lower in order to compensate. Keep your feet at a comfortable distance, slightly less than shoulder width. Do not let your arms move away from your body while you are swinging the rope. This shortens the arc of the rope and will cause issues when trying to get the rope around your body at a very fast pace.
Reps and Sets: There is an endless variety and combination of different reps and sets when performing double unders. Because they help to build stamina and explosive speed, double unders are a perfect complement to many other exercises and they can be performed as a stand alone exercise for a certain set time period (30-60 seconds) or they can be combined with another exercise, like burpees, to get an amazing full body cardio workout. Start off by doing double unders for 15-20 seconds and then resting for 15-20 seconds. Add 15 seconds to each duration of double unders until you reach 60 seconds per set. Shoot for a total workout time of 5-10 minutes for beginners and up to 30-40 minutes for advanced individuals.