If 50 is the new 40, and 40 is the new 30, then simple math should tell you: Dumbbells are the new running shoes.

Well, maybe that pattern doesn't exactly add up, but the long, boring, two-hour treadmill sessions are dead. They don't work now, and they never did.

Burning fat and improving your body composition (lean muscle vs. body fat) is best achieved through short intense workouts. High Intensity Interval Training is the most popular form, and people are now starting to realize, reluctantly, that just exercising longer isn't necessarily exercising better or smarter.

So, now, can we get those same people to take it one step further, by convincing them that they can actually gain cardiovascular benefits without ever going near an exercise bike, treadmill, elliptical machine, or any other traditional piece of "going nowhere" equipment?

Scientists performed a study, published in Cell Metabolism, that showed weight training can burn fat with the best of them.

They fed two groups of mice the same high-fat, carbo-loaded diets, to mimic the poor choices of "fast food America."

One group was engineered to have the lean muscle tissue that would be gained through resistance training, while the other mice were left all natural (at least they weren't in the Mitchell Report!).

The new and improved mice saw marked increases in their metabolic rates and actually burned fat without any increase in physical activity, while the control group gained weight and suffered from liver problems and early signs of diabetes.

Even better news, the amount of muscle added to the mighty mice was relatively small and could be easily duplicated through moderate weight training in a short period of time.

So, if you want to speed up your metabolism, burn fat while you sleep, and increase your lean muscle mass, then start lifting your treadmill instead of running on it.