Muscletech pro series muscle builder features a scientifically dosed key ingredient that will help you boost strength and performance. Hard-training subjects, in a 12-week human scientific study, gained 8.8 lbs. Of lean muscle versus the placebo group, which only gained 4.6 lbs.-that’s 90 percent more lean muscle. In another part of the same study, test subjects increased muscle thickness by 96 percent more than the increase for the placebo group. The same subjects experienced an increase in strength that was 147 percent more than the strength increase achieved by the placebo group.