Even though your muscles get a signal to slow down energy use after lifting weights, they still keep building protein—like your body’s repair crew is ignoring the ‘slow down’ sign because the ‘build up’ signal is stronger.

After a single workout with weights, your muscles temporarily slow down their protein-building process, and this might be because a specific energy-sensing molecule (AMPK) gets more active and tells the building machinery to take a break.

When you lift weights, your muscles temporarily stop building protein, but right after you finish, they kick into high gear to repair and grow—this happens because key signaling molecules in your muscles get activated during recovery.

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.

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.

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