Kinesiology of Exercise

Hip Joint Flexion

Hip joint flexion exercises are extremely important for athletes because the muscles strengthened play a very important role in spinal stability. When the hip flexor muscles and the hip extensor muscles are both strong and flexible, the pelvis will be properly positioned to balance the spine effectively in the anterior-posterior plane. The exercises are also needed in running, speed, and quickness movements.

Major Muscles and Actions Involved

The iliopsoas, pectineus, and rectus femoris muscles are involved in hip flexion. In this exercise the thigh is brought forward and up from a position behind the body to ensure a full ROM.

Sports Uses

The action of hip flexion and the muscles involved are very important in all sports that require running, especially sprinting and kicking, and for stepping out to get to a ball or opponent. In sprinting or running this action is needed to bring the swing leg forward quickly for greater stride length and to prepare for stronger backward thigh movement (the pawback).

Exercise Analysis

  • To allow for effective stretching and maximum strength development of the muscles, it is critical that you maintain an erect upper-body position as best as possible. When you do this, and your leg is brought to the rear, it causes a strong stretch of the hip flexors on the leg being exercised.┬áThis pre-stretching then utilizes the stretch reflex, which produces a stronger contraction in the power phase. If you incline your trunk forward as your leg returns to the rear, you will not get the stretch in the muscles to bring the thigh forward.
  • Raising your thigh as high as possible is not necessary in this exercise. It is important to understand that the hip flexors are strongly involved in the initial pull. However, because of the ligamentous structure of the hip, the thigh can be raised only approximately 45-60 degrees past the vertical. When you raise the thigh higher, the pelvic girdle must rotate backwards. To do this, the abdominals, especially the lower abdominals, must undergo concentric contraction.
  • For runners in running based sports, it is important to not drive the thigh too high as it can introduce or reinforce poor running technique. If the athlete drives the thigh upward it creates more vertical forces rather than horizontal, which are achieved from a forward thigh drive. This is especially true when doing this exercise in an explosive manner. For more information on explosive leg movements for running see Explosive Running and Explosive Plyometrics.
  • For further analysis check out our premium Kinesiology of Exercise EBooks.

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