You don't have to lift heavy to build muscle, says new research in April's Journal of Applied Physiology. After 10 weeks, young guys doing three sets of knee extensions with light weights three times a week increased muscle volume as much as guys doing the same with heavy weights, the study found.
The key: Both groups performed each set until exhaustion -- meaning they physically couldn't lift the weight again. (That's exactly how you'll feel after only 15 minutes with the high-intensity muscle building workouts in the Men’s Health Big Book of 15-Minute Workouts.)Full Story >>