How to Do a concentrated hip extension

In this video, you are shown, you are shown how to properly do a concentrated hip extension. You are instructed to lay on the floor, supported on your elbows. With one knee on the floor, you are then told to life the opposite leg off the floor, completely extended, to form a horizontal line from the floor. While lifting the leg to about 40 degrees, you are to contract the muscles of the same glutes at the same time. After, return to the starting position, bringing your leg to form the horizontal line with your pelvis. They instruct you to breath, throughout the exercise.