I was watching a video the other day that was saying that crunches are not good for your spine. A doctor was speaking on that video saying that when you exercise you need to keep your spine in neutral posture. Already having a spine injury, I started looking for other ways to do exercises to strengthen my abdominal muscles. Even though doing crunches is the only way to get a 6 pack, there are many other exercises that’ll help you lose some belly fat.
The plank up downs, the scissors, and the leg drops are good alternatives. I also found this link below that has a few other exercises that one can do while sitting in their chairs. Take a look.