When you do strength training with your muscles stretched out (like in a full squat versus a half squat), you tend to build more muscle. But this works better for people who are new to training than for people who already lift weights regularly. Scientists may have originally overstated how big this difference really is because studies showing bigger effects get published more often than studies showing smaller effects.

When you do exercises that stretch your muscles more through a bigger movement—like doing full squats instead of tiny half-squats—you may build more muscle tissue than when you stay in a shorter, more restricted movement range.

When you stretch your muscles fully during workouts, the ends of the muscles grow more than the middle parts — the stretch makes the muscle ends bulk up more than the center.

Working your muscles through a fuller range of motion during weight training might make them grow a little bigger than training with a shorter range, but it’s not always clear or the same for every muscle.

Even when people lifted with their muscles stretched 22% more or less, their muscles grew about the same — so you don’t need to go super deep or super shallow to get good growth.

If you're already strength-trained, doing full lifts (like fully curling a dumbbell) won't make your muscles grow more than just doing the stretchy part of the movement—so maybe stretching your muscles under load is the real secret to getting bigger.