I have an old total gym from the 90's and it basically can tilt at up to a 45 degree angle. At the top there is a place to put your feet and a way to strap yourself in. Then, you can basically do situps at a 45 degree angle. I did about 30 of these yesterday and plan to do some more today. It's definitely a good ab exercise. For those who go to the gym, I'm sure there is something similar you can use there. I'm not up to date on gym equipment though.