Stretching your muscles during exercise helps, but working out hard, doing enough reps, and showing up regularly matter way more.

Everyone’s body responds differently to workouts—what works wonders for one person might be too much or too little for another, because of differences in genes, energy use, and how fast they recover.

Lifting heavy weights and lifting lighter weights can both build muscle just as well for different people, as long as you do the same total amount of work. It suggests that how hard you push might not be the main thing that matters for muscle growth.

Doing more sets at the gym than you're used to—like going from 18 to 33 sets a week per muscle group—doesn’t make your muscles grow significantly more, even though you might see a little more growth overall.

Studies show mixed results on whether doing more resistance training sets leads to more muscle growth in people who already train regularly. Some findings suggest that increasing the number of sets doesn't necessarily lead to greater muscle gains.

There is not enough scientific research yet to determine whether training muscles at longer or shorter lengths leads to better muscle growth.