Val Slide Leg Curls train both knee flexion and extension at the same time, meaning they optimally work both the front and the back sides of the legs. This is one of the many reasons that this is such an outstanding exercise. Pending on your glute strength you can either do this with your hips up the whole time such as in the video, or by bringing your hips down when you bring legs back in towards your body. You can also progress or regress this exercise by simply messing with the tempo in which you do this movement. There is nothing magical about the Val Slides so feel free to replace them with a towel, slide board, or I have even used socks on a hardwood floor. Use this exercise as a part of a lower body or total body work-out doing anywhere between 6-15 repetitions.
How to:
1) Lay down on your back with the soles of your feet sitting flat on the Val Slides. The Val Slides can be positioned on the carpet, grass, or any other smooth flooring.
2) Ascend into a bridge position so that your knees, hips, and shoulders all line up in a straight line.
3) Without allowing your hips to fall, slide your feet away from your body bringing your legs as straight as possible.
4) Slide your heels back towards your buttocks, pending on your strength level you can do this with your hips up or down.