Sit-ups are great for strengthening the core but doing sit-up after sit-up gets a little boring and it's important to mix up the moves you use to train your core. With this in mind, we've found a five ...

Sit-ups can be a great way to strengthen your abdominal muscles that sit around your stomach. But they can quickly get repetitive and its easy to accidentally lose your form, so when boredom strikes, ...

Core training has always been part of military PT and fitness testing. From crunches to sit-ups, flutter kicks, leg tucks and plank poses, the U.S. military uses many exercises to test core strength.