Weight-lifting dogma has for decades stated that higher weights and lower repetitions were the superior way to build muscle. Now that the ability to map gene function in response to an activity is the new reality, this old myth just came crashing down¹—and with it many people may now be encouraged to build strength and better muscle fitness that is so vital to longevity and good health.

The researchers used analysis of gene signals to measure protein syntheses following exercise, which determines the rate at which new muscle is being formed. The researchers found that exhausting muscles with exercise was more important than the intensity of muscle use in terms of synthesizing new muscles.

This means that using weights that are about 30% of what you could lift once and doing 25 repetitions (enough so you are too tired to do more) is superior to lifting weights three times heavier for 5 to 10 repetitions. After 24 hours of exercise, the synthesis of new muscle was significantly superior to the intense heavy-lifting group. This is really good news because injuries are so common in those who lift heavy weights.