*Start with a weight you know you and do and increase by 5 - 10 pounds each set, hopefully finding, or coming close to, your 3 rep max on the fourth or fifth set.
Tabata Double under
A tabata is eight rounds of 20 seconds of work followed by 10 seconds of rest. During the work interval you do as many repetitions in 20 seconds as possible.
Your score is the least number of reps performed in an interval