If you lift weights with any frequency—and if you’re reading this, you probably do—then you know that veteran gym rats love to fight over a classic gym argument: lifting with low volume and heavy weights, or high volume and lighter weights. For example: One recent study recently suggested that weight doesn’t matter as long as you lift until your muscles fatigue.
In the study, which was published in Frontiers in Psychology, researchers focused on the brain and the neurons that send signals to activate muscles. Researchers asked 26 men—a small number by academic study standards—to work out three times a week for six weeks, to the point of exhaustion, on a leg-extension machine. The lifters performed reps at either 80% of their max (meant to represent lifting heavy) or 30% of their max (meant to represent lifting light).
By the end of those six weeks both groups had built muscle—but the researchers noticed that only the heavy lifters had added about 10lbs to their one-rep maximum.
From there, the researchers used an electric current to measure the percentage of force the subjects generated. They found that the heavy lifters’ nervous systems had adapted to recruit more motor units in the muscles, thereby generating more force. More specifically, the light lifters improved their force production about 0.15% over the course of the study, while the heavy lifters jumped about 2.35%.
“If you’re trying to increase strength—whether you’re Joe Shmoe, a weekend warrior, a gym rat, or an athlete—training with high loads is going to result in greater strength adaptations,” said study lead Nathaniel Jenkins, Ph.D., an assistant professor of exercise physiology at Oklahoma State University. “I don’t think anybody would argue [with the idea] that high-load training is more efficient,” Jenkins said. “It’s more time-efficient. We’re seeing greater strength adaptations. And now we’re seeing greater neural adaptations.”
