There's a lot of complicated discussion online about how to do your lower abdominal exercises, and some of the things people come up with for that are just weird. But when you really come down to it, lower abdominal exercises aren't about equipment or technique - they're about basic physiology.

It's simple to tell whether you're doing upper or lower abdominal exercises. When you lie down flat on the floor, your upper abdominal muscles lift your upper body from the floor, and your lower abdominal muscles lift your lower body. It's that easy. It's that simple.

So your lower abdominal exercises don't have to be complicated at all. The only thing you have to do is lie down, and lift your lower body from the floor. You don't need a machine or anything. You just have to lie down on the floor and lift both your legs up into the air.

It's important to lift both legs, because if you only lift one, you're just exercising the quadriceps and not the lower abdominal. Exercises for the legs are pretty common, and honestly, most people do too many of them - because the numbers are impressive, especially on an inclined leg press. (The 45 degree angle of the pressing motion means you're really only "lifting" a little over half the weight.)

You can, of course, use some ankle weights to make the workout a little tougher. Lower abdominal exercises are great for strengthening your core stability, and providing a natural weight belt of sorts for lifting heavier objects. But what matters most isn't the lifting motion, its the lowering motion - what physical trainers call a "strong negative."

What really does the most work in lower abdominal exercises isn't the rapid lift, but a slow lowering of the legs. By maintaining tension on the muscles for a longer period of time, micro-tears in the muscle tissue inspire the body to rebuild and strengthen the muscles you're using. So slow it down a little, and you'll get a much greater benefit from your lower abdominal exercises.