When young men do a specific type of hard strength training, their bodies send strong signals to build muscle for hours afterward.

When young men do a specific type of hard weight training that focuses on lowering weights slowly, it triggers more muscle-building signals in their bodies compared to other common workout styles, even if the workout time is the same.

When young men do one set of really tiring weightlifting, it gives the smallest boost to muscle-building signals right after exercise, compared to doing max-stretch moves or multiple sets that take the same total time.

Even after working out with weights for 8 weeks, your muscles still respond to a single workout the same way as they did at the start—your body doesn’t get better at signaling muscle growth after training for a while.

If you slow down the lowering part of weightlifting, your muscles might get more damaged and your body might release more of the hormones that help build muscle—this is what the claim says about guys who lift weights.

For guys who don’t lift regularly, doing weight exercises doesn’t change a specific body signal (ERK1/2) 30 minutes after working out, no matter how hard or long they train — so this signal probably isn’t what tells their muscles to grow right after a fasted workout.