Q: After reading one of your articles that discussed the study where light, longer sets built muscle, I was thinking that maybe that’s why X Reps build so much size. Because they’re partial reps where the muscle is stretched, you block blood flow and get more tension time by making the set last longer. Do you think that’s the case—that X Reps work because they make a set last longer?

A: No doubt that ex-tending the set with X-Reps is one reason those power partials are so effective at building more muscle. As you said, you not only pulse at the target-muscle’s strongest point, where it’s elongated, but you also force the muscle to continue firing for five or more extra seconds—which means a longer tension time on any set with X Reps tacked on. That was the ground-breaking finding of that study—that extending tension time was another way to trigger hypertrophic stimulation…