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

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.

If you're a regular gym-goer, doing workouts that group similar muscle moves together or alternate them doesn't seem to make a difference in how much stronger or bigger your muscles get after 8 weeks.

If you're a regular gym-goer, doing workouts that pair similar muscle groups together (like two push exercises) or alternating push and pull exercises both work just as well to build strength and muscle size over 8 weeks.

When older men do heavy weight training, some get much stronger and build more muscle than others—even when they do the same workout—and those differences are bigger than any mistakes we might make when measuring them.

If you lift weights until you can't do another rep, or stop just before failure, your thigh muscles grow about the same amount after eight weeks — but stopping short feels less exhausting each time.