Greg gthuotte@cox.net

I have tried all kinds of crunch exercises over the years because I get bored with doing the same ones. Reverse crunches are tough and put pressure on various places that can sometimes even cause injuries.

Try this one. Lie on your back. Put your hands behind your head. Do what I will call half crunches. Keep your knees bent. Begin like you are going to do a situp but just go about half way up, pulling your stomach musles in with tension. Your shoulder blades should come off the matt (make sure you use a matt!) but your lower back should remain on the matt. You should feel the tightening of the stomach and abs. It also helps as you do this to almost push your lower back into the matt using your stomach and ab muscles.

You can also do these using a stability ball. It takes a bit more practice but you don't need to get all the way down on the matt.

Hope this helps! Good luck.

The key to exercising your abs (your core is much bigger than your abs) while keeping your lower back safe is to engage the lower abdominals and keep your lower back in the neutral position while working your abs. 

Lie on your back with your knees up. You lower back is now slightly off the floor in the neutral position.

You have three layers of abdominal muscles: at the surface is the rectus abdominis (the washboards in our next life). Under that are the obliques which cross over the belly and under that is the transverse abdominis which goes around your waist like a belt and attaches to your spine. People tend to focus on the rectus abdominis (RA), but it is the transverse abdominis (TA) that gives you 'core strength' and, more importantly, that improves your posture and keeps your lower back healthy. So it is the TA that you need to engage even when you are doing crunches for the RA. 

In the position on the back that you are in tighten all the muscles around your waist, as if your putting on a tight pair of jeans or getting into a corset. Keep this corset of muscles engaged as you do your mini-crunch. Do NOT let your lower back come to the floor, keep it still. This means you're not coming up as far, but you're using the muscles effectively and keeping your lower back safe. 

Another one you can try in the same position is to bring your knees up, but keep them behind your hips, bending them so the lower legs are parallel with the floor. Keep the muscle corset tight to keep your lower back from moving out of the neutral position. Now slowly straighten one leg and lower it towards the floor. When you start feeling tension in the lower back, or if you can't keep your lower back from moving up: bring the leg back to its starting position. 

Don't forget to work your sides and back and pelvic floor as well for true core strength.