Even if you’re already strong—squatting almost twice your body weight—adding more sets will make you stronger, but won’t make your muscles grow more than doing a moderate amount.

For men who already lift weights, doing either high-intensity or high-volume workouts for 8 weeks didn't make a big difference in leg strength or muscle size.

If you're a guy who already lifts weights, doing 4 workouts a week for 8 weeks will make you way stronger—adding about 25 pounds to your squat and 10 pounds to your bench, whether you stick to the same routine or mix it up.

If you're a guy who's already used to lifting weights, doing heavy sets with long rests works just as well as doing more reps with shorter breaks when it comes to getting stronger in the squat after 8 weeks.

If you're a guy who's been lifting weights for a while, doing either 2 or 4 workouts per week for each muscle can boost your strength by about 8–11% in just 8 weeks—as long as you do the same total amount of work overall.

If you're already strong and lift weights, training each muscle group either once or five times a week for eight weeks will give you about the same strength gains on the bench press, squat, and row.