Originally Posted by HardwoodLegend
It's only hard on the back if the back is weak and in need of strengthening, right?
No. Because they will weaken the back over time and could lead to disk issues.
Lots of folks are saying planks are better core exercises.
If you like crunches get an exercise ball because when you do crunches on an exercise ball you're working the back in two directions.
You should google better than crunches and you'll find lots of suggested exercises.