Sadly, these exercises have grown synonymous with strong, attractive abs and they are probably what you see everyone doing in the gym too. It turns out that crunches and sit-ups are incredibly ineffective for developing core strength. And crunches and sit-ups actually do more harm than good! I will just use crunches as an example from now on, but keep in mind the same rules apply for sit-ups.
Let me know! Are you guilty of doing endless crunches and sit-ups? How long can you hold a plank?