Willis recommends runnning these exercises "circuit-style," doing 40 seconds on, 20 seconds off. "Three rounds if you're ...

These seven exercises crank up the intensity by targeting your abs, obliques, lower back, and hips while also getting your heart rate up. Do each move for 30–45 seconds, rest for 15–20 seconds between ...

Doing crunches is a great way to build your core strength, but that can only happen if you're doing them correctly. Here, a trainer explains how to do them properly.

While sit-ups and crunches are great for building strength and stability in your core, they aren’t essential. If you’re bored ...