As long as you’re lifting to the point of fatigue, you’re probably going to build muscle whether you lift light or heavy weights, according to a new study conducted by researchers at McMaster University. Contrary to the belief that only heavy weights will help you bulk up, the researchers found that lifting lighter weights with repetition accomplish the same effects on your muscles.
It all has something to do with how far you push yourself in either situation. “Fatigue is the great equalizer here,” said Stuart Phillips, a professor in the department of kinesiology at McMaster University and senior author of the study, in a press release. “Lift to the point of exhaustion and it doesn’t matter whether the weights are heavy or light.”
In the study, the researchers gathered two groups of experienced male weight lifters who were taking part in a 12-week, whole-body lifting regimen. The first group of men lifted lighter weights that were up to 50 percent of maximum strength, reaching sets with 20-25 repetitions. The second group lifted heavier weights up to 90 percent of maximum strength for sets with 8-12 repetitions. The researchers had both groups lift weights until the point of exhaustion.
Afterwards, they took muscle and blood samples to measure muscle mass and muscle fiber size, both of which measure strength, and found that they were equal in both groups. “Increases in lean body mass, as an indirect measure of muscle mass, and muscle fiber CSA, a direct measure of muscle area, occurred in both [low- and high-repetition] groups with no difference between groups,” the researchers concluded.
It was commonly believed that muscle fibers bulked up more if you lifted heavy weights, while lifting lighter weights for a long period of time didn’t have the same effect. But the latest study debunks that myth. Past research had found similar results: that there’s not much of a difference between heavy and light lifting when it comes to muscle boosting. However, more research will be needed in order to confirm their conclusion.
WHAT THIS MEANS FOR THE AVERAGE PERSON
People, especially women, who’ve wanted to keep their slender figure have often avoided lifting weights to prevent bulk. But the research found that in spite of past beliefs, the participants’ muscle growth and strength wasn’t at all related to testosterone or any growth hormones. And in fact, lifting weights — whether heavy or light — can have a beneficial and protective effect on overall health.
In addition to building muscle that can protect your bones and joints, as well as improving endurance, weight lifting could even boost your memory. It also increases metabolic rate in women, aiding in weight loss.
“At the point of fatigue, both groups would have been trying to maximally activate their muscle fibers to generate force,” said Phillips in the press release. “For the ‘mere mortal’ who wants to get stronger, we’ve shown that you can take a break from lifting heavy weights and not compromise any gains. It’s also a new choice which could appeal to the masses and get people to take up something they should be doing for their health.”
Source: Morton R, Oikawa S, Wavell C, Mazara N, McGlory C, Quadrilatero J. Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men. Journal of Applied Physiology, 2016.
