Lying hip abduction is a great exercise for working the Glute Medius, a hip muscle which stabilizes the knee during single leg movements such as walking, running and one leg squats.
Weakness in this muscle can cause problems such as chrondromalacia patellae (softening of the knee cartilage), Patellar tendinitis, patellofemoral syndrome or the more common “runners knee.” To strengthen the Glute Medius, use the isolation exercise outlined below.
Muscles involved: Gluteus Medius, Gluteus Minimus
Action: Lie on your side with your bottom leg bent and top leg straight and with hip slightly hyperextended. Slowly raise your thigh up and down for the desired number of repetitions. Then repeat on the other side.
Comments: Be sure to keep your hip stationary. You can check for any unwanted movement by putting your hand on your hip. You also want to keep your femur (thigh bone) internally rotated, which you can check by watching to see that the side of your foot is flat when you raise your leg.