Want to build up your muscles in time for beach season? High reps with low weights may be the way to go, a new study suggests.

"There is nothing magical about heavy weights beyond the fact that they make you work hard," says researcher Nicholas Burd, PhD, of Maastricht University Medical Centre in the Netherlands.

In a series of experiments, Burd and colleagues tweaked some resistance-exercise variables to see which had the greatest effect on building muscle mass. More repetitions with lighter weights can build muscle as well as heavier weights -- assuming they are done to the point of exercise-induced fatigue.

And fatigue is the important point. That means even with light weight, the last two to three reps should be hard.

The findings appear in the June issue of Applied Physiology, Nutrition, and Metabolism.

This is not a slight to working out with heavier weights. They are effective at increasing muscle mass, too.

"However, certain conditions may preclude an individual to train with heavy weights, such as the frail elderly, an athlete recovering from injury, or maybe [someone with] no access to heavier training weights," Burd says. "The bottom line is that there is nothing wrong with lifting heavy weights. Our work simply highlights that heavy weights are not the only way to build bigger muscles."

High praise for high reps

The new findings are music to Jordan Metzl's, MD, ears. He is a sports medicine doctor at the Hospital for Special Surgery in New York City. They reinforce everything he tells his patients and what he does in his own life. "High reps with lower weights a couple of times a week is the answer."

He encourages injured athletes and weekend warriors to engage in this type of strength training to help build the muscles around damaged joints or ligaments. "It helps prevent and treat injuries."

To keep your muscles guessing, mixing high reps and low reps, either in the same or different workouts, is a great way to stimulate muscle growth and prevent boredom.