By now you know if you want to build a lean, fit body, you can’t stick to the treadmill or elliptical alone. It takes some heavy lifting to get that strong and chiseled physique. In fact, even if you want to be a better runner, you still need to incorporate strength training into your routine. But when you’re strapped for time, and need to squeeze cardio and weights into a single sweat session, which should you tackle first? Strength training, according to the recent research and fitness pros. Here’s why.