Should you lift light or heavy? There's a lot of conflicting research surrounding this. A study came out last year saying you can get the same outcome from lifting light weights as you can from lifting heavy ones, as long as you do more repetitions. The added benefit is a lighter load on joints, which is great for longevity. But new research out of the University of Nebraska–Lincoln contradicts this notion. The results of this study suggest that lifting heavy loads leads to greater muscle gains than lifting light weights at high repetition, which could be because when we lift heavier weights, our brains send electrical signals to the muscle that the body is working hard, leading to greater strength.
"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 author Nathaniel Jenkins.
So, should you lift heavy? Here's what the experts have to say.
Your muscles adapt quickly.
According to active recovery expert and A.C.C.E.S.S. founder Rebecca Kennedy, if your goal is gaining muscle, you won't get anywhere fast by lifting 2-pound weights. Or if you do, you'll eventually plateau. "You want to get stronger? Well, eventually your body adapts to whatever resistance you apply to it," she says. "That said, you must increase the load to gain more strength. If you're doing body-weight exercises, then you have to add more volume and repetitions."
She adds, "Long story short: If you never increase your load (weights that you lift), your strength doesn't continue to increase. Be patient, increase gradually, and you'll get stronger."
Dr. Dennis Cardone, chief of primary care sports medicine at NYU Langone Orthopedics, agrees with Kennedy's sentiment. "If muscle mass is the goal, heavy lifting is the way to achieve this. But if you simply want to tighten and tone, that's a different story."
When muscle mass isn't the goal.
Of course, not everyone is looking to add muscle mass—some people simply want to tone up a bit or keep their muscles and joints strong as they age. "If you want to tone, lighter lifting is better," says Dr. Cardone. "If you are over the age of 40, it is recommended that you lift less weight with more repetitions to avoid injury. Muscles at this age are more at-risk due to decrease in elasticity, which makes them more injury-prone."
Kennedy says that in addition to watching out for your joint health as you age, you should be wary of adding too much weight too soon. "Lifting too heavy too soon just increases your likelihood of injuring yourself strictly because you're more likely to compensate to lift the load," she explains. "And when you're doing movements incorrectly, then you're risking injury."
As long as you're careful, if you're looking to make muscle gains, it might be time to invest in a pair of heavier weights.
Not into lifting heavy? Read up on why slow fitness is having a moment.