High Reps or Heavy Weights: What’s the Best Way to Get Stronger?

Does it matter if you use high-rep sets or low-reps with heavier weights? Credit: Mike Harrington / Getty Images

If you need an Excel table to track your sets, reps, and one-rep max percentages, you’re making your strength training more complicated than it needs to be. A recent study published by the Journal of Applied Physiology suggests that how many reps you do or how much you lift has little impact on your strength gains and muscle growth. What does actually matter? Effort.

The study, conducted by the Department of Kinesiology at McMaster University, randomly divided 49 men who all had experience lifting weights into two groups. The first group followed a full-body training program that prescribed a high number of repetitions (20 to 25 reps per set), and at about 30 to 50 percent of the max they could lift. Men in the second group followed the identical program, but they worked with heavier loads — between 75 and 90 percent of their one-rep max, and they performed sets of 8 to 12 reps. No matter the working weight and rep scheme, participants were instructed to lift until they were unable to complete another rep.

After 12 weeks, the researchers assessed the participants’ maximal strength and body composition. Verdict: There were no significant differences between high rep-ers and heavy lifters; both groups experienced comparable strength gains and increases in muscle mass.

“The main thing, when it comes to weightlifting, is consistency and challenging yourself,” says Pete McCall, M.S., adjunct faculty in Exercise Science at Mesa College. To stimulate muscle growth, your body must regularly experience a level of stress that’s higher than what it’s used to. The goal is fatigue, but you can get there any number of ways — particularly good news for guys who find complex lifting plans tedious, and frequent travelers forced to make do with sparse hotel fitness rooms.

McCall points out that many hotel gyms only go up to 30 or 40 pounds on the dumbbells, but that needn’t stop you from getting a good workout. "Instead of doing 10 reps to fatigue, you’ll probably have to do 20 or 25 reps — but that’s still going to be enough to stimulate muscle growth and maintain your gains.” Lower weight and higher reps is also ideal if weight loss is among your goals. “Weight loss is all about expending energy,” explains McCall. “If you’re doing 20 to 25 reps, the amount of time the muscles are under tension is going to be longer than doing just six reps.”

This “go hard, or go home” ethos does come with one important caveat: you shouldn’t lift until failure during every workout. This can lead to overtraining and injury. When working with athletes, McCall programs a week or two of bodyweight movements for every six to eight weeks of heavy weightlifting. “This allows the tissues to recover, it allows the joints to recover, and keeps you mentally fresh,” he explains. He’ll often coordinate a recovery phase with a client’s high-stress period at work, like budgeting season or the week before a product launch. But once the dust settles, he ramps up the intensity. Similarly, your resistance training should include periods of recovery and lower-intensity workouts. Otherwise, you’ll set yourself up for failure (and not the good kind).