Kinesiology of Exercise

Hip Joint Extension

To strengthen the gluteus maximus and the hamstring muscle group, most bodybuilders and athletes do squats and lunges. However, most of the visible results from doing these exercises are in the quadriceps because most athletes or fitness buffs do not, or cannot squat or lunge deeply enough to maximally tax the gluteus maximus. To remedy this situation, you should do straight-leg hip extensions (pull-downs or push downs), which are excellent exercises for strengthening the gluteus maximus and hamstrings

Major Muscles and Actions Involved

The gluteus maximus and hamstring muscles are involved in hip joint extension. In this exercise only the upper tendons (together with the hamstring muscle) undergo great activity and shortening. The lower end hamstring muscle tendons are relatively quiet. In hip joint extension the leg moves downward and backward from a forward (hip-flexed) position until it is under or slightly behind the body.

Sports Uses

Hip joint extension and the muscles involved are very important in the execution of many basic skills such as jumping for height or distance and all forms of running, skipping, leaping, and lifting.

Exercise Analysis

  • To moreclosely duplicate the pawback action in running when doing the exercise in the standing position with Active Cords, be sure to straighten your leg as you begin the downward movement. On the push (pull) to the bottom position, keep the leg straight as you go down and back. This keeps the muscle more taut resulting in a stronger muscular contraction. This is also the action seen in sprinting. 
  • Maintaining an erect body position is very important for proper execution in the standing variants. If you lean forward as your leg is being pulled down and back, you will negate the action at the hip joint. When you maintain the erect position, the muscles will be more strongly contracted through the full range of motion. 
  • It should also be noted that when your leg passes the vertical position, that is, when it passes the midline directly under your body, your pelvic girdle must rotate anteriorly to allow the leg to go to the rear. This is an important feature in many sports that allows you to create a greater ROM. 
  • However, note that the muscles involved in rotating the pelvis are the erector spinae muscles of the lower back. The hip extensor muscles remain under isometric contraction to keep the leg-pelvis complex working as a unit. This means that the hip joint extensor muscles are not actively involved. They serve as stabilizers. 
  • The gluteus maximus and hamstring muscles are most effectively worked when you start with your leg in a hip-flexed position. Their dynamic involvement ends when the leg is in line with the upper body. Although this exercise involves the erectorspinae muscle group, these muscles come into play only when the hip jointextensors switch to the isometric contraction. Also the erector spinae are not worked very strongly. 
  • Because of the importance of the hip extensors in most sports, many exercises have been created to help duplicate the exact actions that occur. Thus, in addition to the four above exercises there are also the good morning and deadlift
    exercises. They are described further on in this volume.
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