Both heavy and light weight training, done until exhaustion, didn’t change how hard participants could push or pull in a static muscle test after nine weeks.

Lifting light weights for nine weeks didn't make people stronger on a machine that tests muscle power at different speeds, and in fact, their performance slightly dropped — while heavy lifting kept their strength steady.

If you lift weights until you can’t do another rep—whether you use heavy weights or light ones—you’ll end up with about the same muscle growth after nine weeks, as long as you’re putting in the same effort and number of reps.

If young, healthy guys lift weights for 12 weeks, their muscles get stronger at moderate speeds — like kicking or swinging — and they can generate 13% to 32% more force, no matter how they did the lifting.

Doing light weight exercises until you can't do any more for 8 weeks won't make your arms stronger or more powerful if you're new to lifting — you probably need to lift heavier or move faster to see real gains.

The tools used to measure muscle size and strength were very consistent and accurate, so the results can be trusted.