How many sets do I need to do with the X3?Updated a month ago

With the X3, you only need to do one set to exhaustion to achieve effective muscle growth! 

One set with X3 brings a more complete level of fatigue than compared with conventional weights. Comparisons should not be made with the number of sets. Multiple sets are used with regular weight because the stimulus is delivered only in the weakest range of motion when the least amount of muscle is firing. This means very little stimulus, but with X3, all ranges of motion are taken to fatigue.

However, if your focus is more on muscle size, see the X3 Hypertrophy Program.