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.

If young guys lift weights for 12 weeks, their muscle strength gains in the leg press don’t seem to be linked to how much their hormones spike right after each workout.

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.

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.

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 trained men do certain types of weightlifting workouts, their bodies produce more lactic acid compared to other workout styles, which means their muscles are working harder and under more stress.