If you hate hitting the gym, or travel frequently, you can still increase the size of your muscles even while using lighter weights. At first, this may seem counterintuitive. You have to lift heavier weights in order to recruit more muscle fibers, and build muscles. Researchers from McMaster University, though, found that working to fatigue with lighter weights gets you the same end result. The study, published in the Journal of Applied Physiology, assigned men—their legs, actually—to one of three different exercise groups: • three sets to fatigue at 30% of one-rep maximal strength; • one set to failure at 80% of one-rep max; or • three sets to fatigue at 80% of one-rep max. After 10 weeks of exercise, three times a week, each group saw significant gains in muscle volume—as measured by MRI—with no difference among the groups. Previous measurements by the same researchers, though, showed, greater protein synthesis with three sets compared to one. So if you’re looking to increase the size of your muscles without all the equipment, lift at 30% of your one-rep max until you are fatigued. Then rest, and repeat for two more sets. This type of workout can easily be done while traveling or in your own home. If you want to be able to lift heavier weights, though, you are still going to have to use heavier weights in your workout. The researchers found that isotonic muscle strength increased the most with the heavier weights. No big shock there.