Even though both muscle thickness and total lean mass went up after training, they didn’t change together in a predictable way—meaning one might not be a perfect stand-in for the other.

When muscles get bigger from lifting weights, the way we measure it (ultrasound vs. body scan) doesn’t always line up—so they might be capturing different kinds of changes, not just muscle growth.

More lifting helps, but only up to a point—after that, each extra set gives you less and less benefit, no matter if you’re trying to grow muscle or get stronger.

When people who already lift weights do either short breaks between reps (cluster sets) or long continuous sets (traditional sets), both ways make their muscles grow about the same amount if they work just as hard and do the same total number of reps.

When you lift weights over time, the main reason your body becomes leaner and more muscular is because your muscles grow bigger—not because you're losing fat or anything else.

The lower part of the thigh doesn't get noticeably bigger after 8 weeks of any of these training styles, even if the upper and middle parts do—meaning muscles don't grow evenly everywhere.