If you're a guy who lifts weights, doing more reps with lighter weights (which spikes your hormones more) doesn't build more muscle or strength over 8 weeks than lifting heavier weights with fewer reps—even though the hormone changes look different.

When men who lift weights start training, doing more reps with lighter weights causes a bigger short-term boost in certain hormones compared to lifting heavy weights for fewer reps. But this hormone boost gets smaller the longer they keep training.

Even if you lift heavy or light weights for 12 weeks, your body’s short-term hormone spike after each workout doesn’t change—and that means those hormone surges probably aren’t why your muscles get bigger or stronger over time.

When young men do intense leg workouts, their body releases more lactate and cortisol—stress and energy chemicals—but that doesn’t mean they’ll grow bigger muscles or get stronger faster than if those chemicals stayed low.

Even though lifting weights with short breaks makes your body release more growth hormone, that doesn’t mean you’ll grow bigger muscles over time.

Even if your hormones spike after a tough workout, that doesn’t mean you’ll grow bigger muscles or get stronger over 12 weeks of training — the spike and the results don’t seem to go together.