I work out at home, and I do ab crunches as part of my workout. My sister says that doing crunches on the floor isn't good for your back, and can hurt it. I do my crunches on an exercise mat (2" thick). In the past few days, my lower back has been hurting some. I don't know if it's because of the crunches, or if it's in relation to me doing household cleaning. I've been cleaning out my room yesterday and today. And today, I scrubbed all of the bathroom sinks and toilets in the house (which hurt my back too).

Does anyone get back pain from doing crunches on the floor? I saw infomercials for the Bender Ball thingy, and I definitely wanna get something like that. TIA. :)

I love doing crunches on a stability ball (those big exercise balls). You can get one for $10 at Walmart. Your back won't hurt, and I find that my crunches are a lot more effective (perhaps because your core is already engaged in helping you balance on the ball, and because you can go farther back than if you were on the floor).

If you're doing your crunches on a mat with proper form, your back soreness is more likely to be due to the housecleaning. Back muscles need to be excercised, and we usually forget. Add cobras (see "Yoga") to your routine, and try this one:
Get on your hands and knees, extend your right arm in front, and your left leg behind you with a nice, flat back. Keep your head in neutral. Hold for 15 - 20 seconds, and do the other side. Start with 5 reps and work up to as many as you need. That's a gentle strengthener that puts no strain on the spine or the sacroiliac joints.

I'd say it's the housecleaning that's hurting your back, moreso than the crunches.

As long as you're keeping proper form during the crunches, you shouldn't experience any back pain from them ... are you making sure not to strain yourself in any way? Keeping your chin away from your chest, like there's an orange tucked under your chin?

I agree with Christine - as long as you're doing them properly you shouldn't be having any back pain. Most likely it is from the housecleaning. I know that when I have done a full day's worth of housecleaning, I'm usually sore and tired afterwards!