By Nora Tobin for Shape.com
Just as a well-built house starts with a solid foundation, a truly fit body starts with a strong core. Whether you're hoisting weights, chasing balls, or just sitting up straight at a desk, your core muscles help you do it better, with less effort and less risk of injury.
When performed properly, most compound exercises such as squats, deadlifts, and rows require your core to engage, so it's not always necessary to devote an entire workout to training those muscles. But since when was only doing what's truly "necessary" the fastest way to reach your goals? Dedicate just one hour a week to training your core and you'll notice flatter, more defined abs, better posture, and improved sports performance (thanks to more support from your deepest abdominal muscles) in less time.
How It Works: Once a week, perform 1 set of each exercise in order. After the final exercise, rest as needed, and repeat the full circuit 2 more times. If you want an extra dose of calorie-burn, do 15 minutes of jump rope intervals (20 seconds on, 10 seconds off) immediately after this workout.
You'll need: A mat (optional).