Muscles that abduct the human leg include the gluteus medius and gluteus minimus, which are in the hips. These abductor muscles move the leg out to the side in a standing position or move the knees out to the side from a squatting position. Abduction is the act of moving a body part away from the midline of the body. Leg abduction moves the entire leg to the side.
Abduction is just movement of the leg to the side, not forward or backward. Arms are abducted by reaching out from the shoulder. Jumping jacks abduct all four limbs of the body by moving legs apart and to the side while moving arms to the side and then up. Leg lifts done by lying on the side strengthen hip abductors. Workout machines move these muscles, but the same motions are achieved by cable machines.
Getting the leg to move forward and backward is called flexing or extending, respectively. These actions differ from abduction since abducting muscles just moves limbs to the side. Hip flexions, such as the quadriceps, move the leg forward. Hip extension occurs due to the hamstrings and gluteus maximus. Muscles around the knees and ankles move these joints using extensors and flexors but not abductors.