Master The Singleunder, Doubleunder, and the Tripleunder.
Dave Newman is the resident expert on doubleunders. In the January 2015 issue of The CrossFit Journal Hilary Achauer captures the basic skill as Dave teaches doubleunders. He breaks the movement down into three parts: bounding, rotational mechanics and timing.
Bounding is the upward movement and posturing of the body. It is crucial for the jumper to have a solid midline stabilization. Just follow Dr. Kelly Starrett's bracing technique: screw your feet into the ground, squeeze your butt, take a breath, balance you rib cage over your pelvis and tighten your belly as you exhale. Finally, set your head and shoulders in a neutral position. If you sustain this position (sans the grounded feet) your posture will be just right for success.
Bounding is the actual movement off the ground, your single, double, or triple jump is determined by your height in the jump, not your rotation of the rope. Jump up and down: singles, slight heel touch, doubles, only your toes and 90% calves, triples, all toes and your amazing!
Rotation is your rope movement. If your posturing is right, then you establish your rotation with your single unders. Follow Dr. Starrett's' posturing as outlined above and relax your hands by your sides, palms forward and wrists turned out. You should see your hands slightly in your peripheral vision. Don't move your arms, just your wrists. The body and appendage positioning shouldn't change. Ever. Turn the rope and try not to let your hands travel outward, away from your body.
Lastly, the jumper will need to work on the timing. Most people jump too soon; right as they see the rope, but the trick is to jump right after the rope passes the knees.
Auchner's article is a great read. She offers techniques to improve your bounding as well as tips to find out how to improve your rotation and perfect your timing She also reveals the secret of the triple under.
Achauer, H. (2015). Double, Double, Toil And Trouble. The CrossFit Journal. January.
Starrett, K., Cordoza, G. (2015). Becoming A Supple Leopard. Victory Belt Publishing Inc., 4041.
1) Coach led Warm-up
2) for time complete
100 Double unders
25 Broad Jumps
1) EMOM for 5 minutes complete 3 power snatches starting at 55% + 5Lbs of your max snatch and adding 5 lbs each minute.
2) EMOM for 5 minutes complete 3 power cleans plus 1 jerk starting at 55% + 5lbs of your max and adding 5 lbs every minute
3) Back Squat 1X5@ 70%, 1x5@ 75%, 2x3@ 80%, 1x3 85%, 2x1@ 90%
4) 3 rounds for time of
20 wall balls 30/20
15 box jumps 30/24
10 C2B pull-ups