Try performing a squat against a wall by sliding your back down the wall until your knees are at a right angle, shins vertical. Place a large ball (such as a football) in between your knees and squeeze it. This activates the Adductor muscles and because VMO arises from the tendon of Adductor Magnus, also stimulates VMO to contract. Hold this for 5 seconds and repeat it 10 times, gradually increasing to 5 second holds and 20 repetitions. Be careful while performing . tendon may get tear if its overstretched.