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.

When trained men do different types of strength exercises, their muscles produce more lactate (a sign of effort), and it peaks at similar high levels after ten sets, showing their bodies respond the same way to all the workouts.

When men who already lift weights do lots of reps with lighter weights, their muscles produce more lactic acid buildup than when they lift heavy weights for fewer reps, both right away and after two months of training.

Even though one method uses lighter weights with pauses and more reps, and the other uses heavier weights with fewer reps, both make the muscles equally tired in terms of lactic acid buildup.

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.

When people who lift weights do superset training (doing exercises back-to-back without rest), their bodies produce more lactic acid and burn more energy during and after workouts compared to regular training. This means their muscles work harder and get more stressed.