Even though the muscles grew bigger, the body didn’t make more muscle or connective tissue proteins at a faster rate — meaning the growth happened without the usual increase in protein building.

Even though the muscles got bigger after the exercise, the number of special repair cells and nuclei inside the muscle fibers didn’t go up — meaning the growth happened without these typical building mechanisms.

Doing light weightlifting with a band that restricts blood flow for six weeks can make both slow and fast muscle fibers in older people grow bigger by about 20%, even without heavy lifting.

If you lift heavy weights or do lots of reps with lighter weights, your muscles grow at the same rate—so it doesn’t matter which way you train, as long as you’re already fit.

Doing short bursts of intense exercise can help your muscles make more proteins, especially the ones in energy factories inside cells, but it doesn’t always make your muscles bigger if you only do it for less than six weeks.

Your muscles make more protein at first when you start lifting weights, but after a few weeks, that boost fades—even if you keep lifting harder.