The Double-Under

Janine - I think the key is finding a nice consistent pace and sticking to it. Think jogging vs sprinting. Try to be as efficient as you can with the jumps i.e. dont jump too high and expend more energy than needed. 

I agree with everything Steve says, finding a consistent rhythm/tempo is way more important than speed. I'll never be an expert but have put a lot of focus on DUs lately and have found that slower is better - it helps me with breathing, less shoulder/arm fatigue and messing up a little less.