If you're a young guy lifting weights, your muscle growth and strength gains might be easier to predict if you treat big multi-muscle exercises (like squats) differently in your workout plan than isolated moves (like bicep curls).

Most of the research on how much to lift and how often was done on young men who already train—so we don’t know if the same rules apply to women, older people, or beginners.

When you lift weights, how much total work you do matters more for getting stronger and bigger than whether you use heavy weights with few reps or light weights with many reps.

Not all sets count the same—sets that directly target the muscle you're measuring matter more, and a method that gives partial credit to indirect sets works best for predicting results.

If you're already used to lifting weights, doing more sets and reps over time will help you build bigger muscles and get stronger — but only if you keep training consistently.

Doing more sets in your weight workouts might actually make you gain less muscle—each extra set could slightly reduce your muscle growth, so more isn’t always better.