You can do this exercise either at the gym or at home. If you prefer to do them at home, you may be more comfortable performing this exercise on a yoga mat, towel or any other soft surface you can put between you and the floor.

This exercise works your rectus abdominis muscles, which are the major muscle group in your core and the muscles responsible for the six-pack look. Spider-mans also work your deltoids, which are your shoulder muscle; your gluteus maximus, which are your butt muscles, and your quadriceps, which are located on the front side of your thighs.c 

1. Lie on your stomach on your mat. Raise yourself onto your elbows and feet so that your entire body resembles a inclined plank of wood. Contract your abs.
2. Keeping your spine in the same alignment, bend your right knee and bring it out to your right side so that your leg is parallel to the ground and your knee is in line with your hip.
3. Return your right leg back to start.
4. Repeat for the other side. Bend your right knee and bring it out to your right side so that your leg is parallel to the ground and your knee is in line with your hip.
5. Return your left leg back to start to complete one rep.
6. Repeat for 30 seconds to one minute.