Often people find when they do a sit-up is that the initial lift hurts, but then the exercise becomes far easier, this is simply because the stomach muscles are not being used any more.

However, there are a few key differences to note for each movement, particularly when it comes to the muscles involved. "While the terms 'crunches' and 'sit-ups' are sometimes used interchangeably ...

endless sit-ups and planks alone won’t do it. Not only does switching things up help you beat boredom, but it’ll also help you engage different muscles to strengthen your entire core.