Do you have to lift heavy to build muscle? Compare 5, 10 and 20 reps

Do you have to lift heavy to build muscle? Not really. Muscle grows across a wide range of reps, from about 5 to 30, as long as your sets finish close to failure, while heavier loads add a little extra strength.

Move the sliders to pick your reps and how many you'd have in reserve, and see the estimated weight, how many reps are truly demanding, and how long the set takes.