For a bodybuilder the leg curl motion is one that can not be neglected. The need of a leg curl machine is quite big if you want to have good legs. There is also a variation that I found to be very interesting. Instead of doing a leg curl on a regular leg curl machine try this approach! Use a flat bench and position yourself on it facedown. Make sure your knees are above the bottom ledge and ask a friend to help you out next. Take a dumbell and ask your partner to position it on the bottom side of the top plates, resting just on your feet. Now you can do a leg curl by holding your legs together and paying attention that the weight does not fall. The exercise will not feel like a regular leg curl but will help you out in your workout once in a while. Your calves are also involved in the movement adding more strength at the end of the session! Try it out! It is quite a nice variation!