Your muscles grow bigger mainly because of how much total force they feel over time—not whether you do your workouts all at once or spread out over the week.

We analyzed the available evidence on whether total mechanical tension is the main driver of muscle growth, regardless of how workouts are scheduled. What we’ve found so far is mixed: 54 studies or assertions support the idea that muscle growth depends mostly on the total force muscles experience over time, while 46 others challenge that view [1]. Total mechanical tension refers to the amount of pulling or pushing force your muscles handle during exercise—like the weight you lift and how hard you push against it. The supporting evidence suggests that whether you do your lifts in one long session or spread them across the week, what matters most is the overall load your muscles carry over time. This means if you lift 100 pounds for 10 sets in one day, or 5 sets spread over two days, the total tension might be similar enough to produce comparable growth, assuming other factors like recovery and nutrition stay consistent. But the refuting evidence shows that how you schedule your workouts—like frequency, rest between sets, or timing of sessions—may still influence muscle growth in ways that aren’t captured by total tension alone. For example, spreading sets across more days might improve recovery, allow for better form, or stimulate muscle fibers differently, even if the total weight lifted is the same. Our current analysis shows that while total mechanical tension is an important factor, it may not be the only one. The evidence doesn’t clearly say one explanation is stronger than the other. In everyday terms: lifting heavier or more often can help you grow muscle, but how you arrange your workouts might still matter—even if the total weight you lift stays the same.