Scientists use tape measures and skin pinches to guess how much muscle people gain from weight training, but these methods aren’t precise enough to notice small muscle gains.

Some trainers count all your lifts to measure workout volume, but this claim says a smarter way is to count only the hard sets fully and give half credit to the lighter, supporting ones — and that this method actually predicts muscle growth and strength gains better than the other ways.

Doing strength exercises with your muscles stretched more or less doesn’t seem to make much difference in how much each part of the muscle grows — all parts grow about the same.

Not all sets count the same—sets that directly target the muscle you're measuring matter more, and a method that gives partial credit to indirect sets works best for predicting results.

No matter which way you measure muscle growth—whether you count all non-fat weight, lean tissue, or just skeletal muscle—you get pretty much the same result when guys lift weights. So, you can use any of these methods and still track muscle gain accurately.

When you're lifting weights, whether you do exercises that target one muscle at a time or ones that work multiple muscles together can change how well we can guess how much muscle you'll build or how much stronger you'll get—and using a special way to measure the workload (called 'fractional') works best for making those guesses.