Training with heavier loads could make it easier to utilize more of your muscles' force, which makes lifting more efficient.
Photo: Larry Washburn/Getty Images
When it comes to weightlifting, people have *all kinds* of opinions about the best way to get stronger, build muscles, and get definition. Some people prefer to do higher repetitions of their exercises with lighter weights, while others would rather do fewer reps with much heavier weights. And the good news is that science has shown that both methods are effective at helping people gain muscle mass and get fitter. In fact, one study in PLoS One showed that lighter weights might actually be more effective at building muscle. (Looks like those arm exercises in barre and cycling class do work.) Still, other research says that those who lift heavy generally see more progress in their strength over a shorter period of time (faster #gains), even when muscle mass is equal to those who lift lighter. (FYI, here are five reasons why lifting heavy *won't* make you bulk up.)
Needless to say, the best way to build strength and muscle is a hotly debated issue in the exercise community, with the Tracy Andersons of the fitness world in one corner and CrossFit coaches in the other. But now, a new study just published in Frontiers in Physiology is giving an extra point in favor of the heavy lifters. The researchers believe that if you lift heavy, you're actually more effectively conditioning your nervous system, which means that it takes less effort for your muscles to lift or exert force than someone who uses lighter weights.
How did they come to that conclusion, you might ask. Well, researchers took 26 men and had them train on a leg extension machine for six weeks, either performing 80 percent of their one rep max (1RM) or 30 percent. Three times per week, they performed the exercise until failure. (Oof.) The muscle mass growth in both groups was pretty much the same, but the group that was performing the exercise at a heavier weight increased their 1RM by the end of the experiment by about 10 more pounds than the lower weight group.
At this point, the results were pretty much expected, based on previous research, but here's where things get interesting. By utilizing an electrical current, the researchers were able to measure how much of the total possible force the participants were using during these 1RM tests. This voluntary activation (VA), as it's technically called, essentially means how much available force the athletes are able to use during exercise. As it turned out, the heavier lifters were able to access more VA from their muscles. Basically, that explains why people who lift heavy experience bigger gains—their nervous system is conditioned to allow them to use more of their strength. Pretty cool, right? (Thinking about getting started? Here are 18 ways weight lifting will change your life.)
And while the research was performed on men, there's no reason to think the results would not be the same or similar for women, says Nathaniel D.M. Jenkins, Ph.D., C.S.C.S., lead author on the study and co-director of the Applied Neuromuscular Physiology Laboratory at Oklahoma State University.
So what does this all mean for you and your workouts? "After lifting with heavier weights, it may take less effort to produce the same force," says Jenkins. "So, if I picked up a 20-pound dumbbell and started performing biceps curls prior to training and then again after several weeks of training, it would be easier to do so the second time around after training with heavier weights compared to light weights." That could also translate into making activities you do in your daily life—carrying groceries, picking up your kid, moving furniture—somewhat easier, he says, since you don't have to work as hard to get the job done. Sounds good to us.
Lastly, lifting heavy weights may also help you make the most of the time you spend in the gym, says Jenkins. That's because you can get stronger faster while still increasing your muscle mass, all while performing fewer reps—thus spending less time working out. Seems like a pretty sweet deal to us, especially for anyone with a hectic schedule. And if you need more convincing, here are eight reasons why you should lift heavier weights.