Adding stretching between your weightlifting sets can help you build more muscle faster than just resting normally, without making your workouts take longer. Research suggests this method can lead to about 10.5% more muscle growth compared to 6.7% with regular rest over two months.

If you're already strength-trained and do upper-body workouts for 8 weeks, it doesn't matter much if you lift all the way up and down or just do part of the motion—your muscles grow and get stronger about the same either way.

Lifting weights twice a week for six weeks — whether using heavier or lighter weights — helps young, healthy guys build leg muscle just about the same amount, compared to not training at all.

Training muscles while they are fully stretched is probably the best way to build muscle size for experienced lifters. Adding exercises that only work the muscle in a shortened position doesn't seem to help you grow more muscle compared to just focusing on the stretched position.

If young men lift light weights with very short breaks between sets for 8 weeks, their upper arms grow more than if they lift heavy weights with long breaks—even if they do the same total amount of lifting—because the short breaks create more muscle-burning stress that helps muscles grow bigger.

When adults who already work out tried a special rest-pause weightlifting method for 6 weeks, their thigh muscles grew 11% thicker, while those doing regular weightlifting only saw 1% growth.