Since Arnold Schwarzenegger flaunted his bulging biceps and quads in 1977's “Pumping Iron,” the rule of thigh (if not thumb) has been that to get strong, you need to lift weights that are uber-heavy -- or collapse trying.

Well, in 2012 we have a new mantra: Pump less and flex more. We've said it before: Start light. There's no shame in using weights that are 1, 2, 3 or 5 pounds. The point is to do what you can until the muscle you're using is fatigued.

Now proof positive has arrived that working out at 30 percent of your maximum strength until you are too fatigued to do one more rep is the smart, safe way to do strength training. (Best case: Fatigue happens within 2 minutes.) That means you'll be using weights that are just a third of the heaviest weight you can safely manage. For example, if you can do one preacher's curl with a 10-pound weight (you curl the weight up to your shoulder), 3 pounds would be the new, smart weight for reps until you can't do anymore.

That approach builds serious muscle strength and keeps the whole body humming at a higher burn rate for longer than if you pumped fewer but heavier reps.

What will this newer approach do for you? Plenty. It helps fight off extra pounds, keeps diabetes at bay and avoids injury to tendons and ligaments. So if you want to banish belly fat and chase away anxiety, take the light and long road to muscle tone and power.

Mehmet Oz, M.D. is host of “The Dr. Oz Show,” and Mike Roizen, M.D. is Chief Medical Officer at the Cleveland Clinic Wellness Institute. For more information go to www.RealAge.com.