Jump Rope
Jumping rope provides a cardiovascular exercise that also builds coordination and accuracy. When CrossFit workouts prescribe jumping rope it is usually the double-under. In the double-under, the rope makes two revolutions when you make one jump. It greatly increases the cardiovascular and coordination demand as compared to single-unders.
Scaling and Substitution
People who can’t do double-unders frequently substitute twice as many single-unders. While this may take about the same amount of time as consecutively performed double-unders, people tend to get stuck doing single-unders and never learn the double-under. For this reason, we recommend 3–5 times the prescribed number of double-unders as a better substitution when using single-unders.
Tuck jumps are also another recommended substitution. They’re good for when you don’t have a jump rope.