The temptation to purchase one of those heavily advertised ab gadgets is strong—especially when you see the results that some users claim to have gotten by using the devices. If you are skeptical about these claims, you should be.

But are they all not worth the money or are some of them actually worth a second look?

Researchers at the Mayo Clinic tested some of these gadgets to find out which ones are most effective. In the end, the Ab Slide (similar to the Ab Wheel) recruited the abs the hardest. However, the truth about six pack abs positioning on the device put a lot of stress on the low back so it is not recommended for people with lower back problems. Overall, the Ab Wheel is the safest and most effective of all the gadgets. The truth about six pack abs, however, is that even the most effective gadgets are not enough. Consistent exercise paired with a healthy diet is all part of the plan to achieve that six pack look.