HIP EXTENSION – an accessory exercise

Hip extension is an important biomechanical function performed by the body.  Among many motions requiring hip extension, the most crucial to human activity is maintaining and upright posture. Nearly all to and fro movements of the body involve some degree of hip extension. This action is linked to many of the everyday requirement and athletic endeavors that humans undertake.

Development of proper hip extension is often overlooked. Use of poor posture, improper alignment, and faulty mechanics causes the body to compensate biomechanically. These compensations facilitate tightness in some muscles and weakness in other muscles. This can lead to issues with the articular cartilage and femuroacetabular joint. Surgery is often required to mitigate the resultant problems. Modern society does not reinforce optimal posture. Therefore, bodily mechanics can over time deteriorate. Posture, supported by good alignment, sets up efficient mechanics.

What is the relationship between walking, running, jumping, standing up from sitting and standing in place? They are different actions that involve hip extension. Hip extension propels the body forward, stabilizes it in an upright position, and assists in running, jumping and hopping. Inadequate hip extension can compromise day to day activities and athletic endeavors. Strengthening the muscles that are responsible for hip extension can insure against possible injury and be a key factor in improving performance of daily activities and sporting endeavors.

Complete hip extension requires coordinating the actions between the glutes, hamstrings, adductors and dorsal musculatures of the trunk. This specific coordination is prevalent from heel strike to heel off as one is walking.  In new gait terminology, full hip extension is evidenced from initial contact through loading response to midstance, in preparation for the glutes and hamstrings to be engaged, during follow through into terminal stance.

Initial contact involves activity of the hamstrings and gluteus maximus which facilitates hip extension. In Midstance,  pelvic stabilization is maintained by the frontal plane muscle activity of the hip abductors. Gluteus Minimus and Medius actively sustain lateral pelvic stabilization in terminal stance. In terminal swing, the Gluteus Maximus and hamstrings become engaged while counteracting hip flexion and knee extension.

How walking is defined
Illustration of different phases of the gait cycle. ( A ) New gait terms; ( B ) classic gait terms; and ( C ) Percentage of gait cycle

Hip extension cannot be adequately expressed without sufficient hip stability. Actions that improve Hip Stability also improve Hip Extension. Improper transfer of forces, through the hip, is a consequence of instability. Inadequate stability impacts negatively on gait and other actions: i.e. running, jumping, swimming, etc. Proper hip stability minimizes the body’s tendency to compensate biomechanically and insures efficient hip extension.

Hip stability is the maintaining of bodily center of gravity and producing strength and coordination in the hips, trunk and core muscles. Hip stability, in tandem with hip mobility, as freedom of movement, gives rise to and facilitates sundry athletic abilities and movement patterns. Strong hip musculature coupled with stable hips is conducive to reducing the risk of injury in the knees, spine and pelvic joints.

The integrity of the pelvis is comprised of five levels. The femuroacetabular joint is the junction between the femur and pelvis and the place from which the movements of the femur originate. The articular cartilage and labrum are the structures that provide lubrication between the femur and the pelvis. The Joint Capsule encloses the femoroacetabular joint, labrum and articular cartilage. The Ligaments connect bone to bone. The Tendons connect bone to the Muscles which enables the body to perform various movements. The pelvis is less prone to injury when the levels function as designed. Proper skeletal alignment and efficient muscular activity ensures the cooperative functioning of the different levels.

The Gluteus Medius is the primary hip stabilizer muscle in the frontal plane. It keeps the active hip from dropping. Strength of this muscle is important. However, correct activation of this muscle is key to maintaining hip stability during any kind of movement. The Gluteus Minimus synergistically supports the actions of the Gluteus Medius. The Gluteus Maximus is a primary hip extensor but also is involved with hip stabilization.

The various musculatures involved with hip extension and their associated actions are listed below. Some of these muscles also stabilize of the hips. The connection between hip extension and hip stability is due to multifunction orientation of some of these muscles.

Hip/Femur External Rotators – synergistic stabilizers of the hips.

  • Obturator Internus: Lateral rotation and abduction of the thigh at the hip.
  • Piriformis: Lateral rotation and abduction of the thigh at the hip.
  • Gemelli: (superior and inferior) Lateral rotation and abduction of the thigh at the hip.
  • Quadratus Femoris: Lateral rotation of the thigh at the hip, plays a major role in extension of the lower leg at the knee as well
  • Bicieps Femoris – Extends, internally and externally rotates the thigh and flexes the knee

    Semimembranosous / Semitendinosous – extends the femur at the hip. Flexes and internally rotates the leg at the knee.

    Gluteus Maximus – Extends, Abducts and Laterally Rotates the thigh at the hip. One of the strongest muscles in the body.

    Gluteus Medius and Minimus – Gluteus Minimus and Medius specifically work together to stabilize us on one leg when either balancing or while we’re walking. The smaller gluteal muscles are the most powerful abductors and internal rotators of the hip joint. A contraction of the ventral fibers results in a flexion and inward rotation. The dorsal fibers perform an extension and outward rotation. Altogether, they play an important role in stabilization of the pelvis.

    Adductor Magnus – The Adductor Magnus has a large hip extensor muscle moment arm. The hip extension moment arm length of the Adductor Magnus changes with hip angle and it is a more effective hip extensor than either the hamstrings or Gluteus Maximus when the hip is flexed. This means that exercises that have peak contractions in positions of hip flexion (like full squats) likely train the Adductor Magnus very effectively.

    Below is a chart that displays the moment arms that occur between 0 degrees of hip angle and 90 degrees of hip angle. The Gluteus Maximus has its shortest moment arm length (is weakest) at 90 degrees angle (hip flexion) and has its longest moment arm length (is strongest) at 0 degrees angle (hip extension). The longer and shorter Adductor Magnus moment arms are in opposition to those of the GM. The hamstrings have a higher moment arm that is most prevalent in between those of the GM and the AM.

    HAG
    Interplay, Interactions between Gluteus Maximus, Adductor Magnus and Hamstrings.

    Moment arm length changes in combination with hip joint angle transitions makes the Gluteus Maximus a very good hip extensor while you are standing upright or in the stance phase of running, and a much less effective hip extensor when you are at the bottom of a squat.

    To develop strength and stability in the hips is critical for daily activities. It is important that the activities be more controlled, for athleticism to be more adroitly expressed and for the individual to be more active throughout their aging years. The hips are important for transference of ground, gravitational and muscular forces throughout the body. All movement involves shifting and balancing of weights and forces between the left and right sides of the body and the ground. This is mediated through the hips. Thus, it is critical to enhance strength and improve stability in the hips for efficient (hip) extension.

    Athletic performance is strongly tied to hip extension. The hips are a main source of the power and force generated for athletic endeavors. The muscular activities associated with hip extension require a coordinated interplay between strength, stability and mobility (SSM). When SSM is properly developed, hip extension is supported and effectively exhibited.

    According to Dr. J. Salvo, clinical associate professor of orthopedic surgery at Thomas Jefferson University Hospital and Rothman Institute, it is best to strengthen the hips by performing exercises that require coordination of all involved muscular groups. By strengthening the hips in this fashion, actions that involve combinations of squatting, jumping, pivoting can become more efficient.

    Flexibility in the hip is an influencing factor upon performance. Inadequate flexibility causes the body to compensate for reduced muscular efficiencies. These compensations can manifest as patterns of overuse of improper muscles. If the compensatory situation is not addressed, it can lead to injury. In some cases, resultant injuries may require surgery.

    Exercises that enhance and strengthen hip extension are of two categories: 1) Primary exercises and 2) Accessory exercises. Primary exercises develop strength and Accessory exercises address hypertrophy and work capacity. Exercises for developing Strong(er) muscles are usually of the type that have two legs working simultaneously. Barbell Hip Thrust, Glute/Ham Raise. Squats, dead lifts are the ‘go-to’ exercises; however, hip thrusts and negative full body hamstring curls are specifically focused on hip extension musculature(s). To develop hypertrophy, work capacity or to prevent injury requires exercises geared toward engaging the muscles that stabilize the hips. Exercises such as One Leg Romanian Dead Lift, Body Curl are good for this. Developing both strength and work capacity for hip extension will improve activities of standing, walking, running, jumping, pushing and the like.

    The exercise that we want to present is based on Warrior III, a yoga balancing posture. Balance postures require kinesthetic awareness of all three planes of motion.  The core region, in particular, must be correctly activated in order for stability to be maintained and for activity to be (properly) supported.  Warrior III is a posture that simultaneously develops hip extension and hip stability. This posture helps with reintegrating hip kinetics; thereby improving kinematic function.

    Warrior III engages a unilateral stance, helping to strengthen and align the muscles and bones of that leg. By  adding cables to the exercise, the leg that performs hip extension is more effectively targeted. This is an accessory, open-chain exercise with minimal quadriceps engagement. The starting angles for the joints of the  extending leg: Hip Flexion / ~130 degrees, Knee Flexion / ~90 degrees.

    Standing on both feet fold forward at the waist (hip flexion).

    Place hands on a wall and shift weight onto one foot. Slightly lift the unweighted foot to ankle height. Extend the working foot back so that the foot-knee-hip are aligned. Establish the squareness of the hips. The hips must be level.

    There are two options that are available if the hips are not level. Move the hands up the wall by adjusting the alignment through the hand-shoulder/torso-hip line. This will be the working position.

    Re-establish the working position with the arms outstretched. One hand placed on the cable station upright, place the other hand on a support.

    The height of the hands should be placed such that alignment goes through the hand-shoulder/torso-hip line. Maintain the squareness of the hips.

    Stand on the supporting foot and square the hips. Extend the working foot back and up. Keep the core engaged, the supporting leg active and the spine long. Working foot and leg are at hip height when finished.

    The supporting leg and torso are aligned in hip flexion. The muscles of hip extension are isometrically engaged. Specifically, the Gluteus Maximus, Semimembranosus, Semitendinosus, Adductor Magnus maintain the position of the torso. Gluteus Med / Min and hip external rotators maintain hip stability.

    The working leg is positioned such that the Gluteus Maximus, Semimembranosus, Semitendinosus and Adductor Magnus are at various stages of engagement. The Gluteals are more active towards full extension and the Addutor Magnus is more active when the hip is flexed.

    Hip extension is the action of the femur moving away from the torso; the femoroacetabular joint being the central axis for the movement. Hip extension is closely to hip stability. Improving hip stability will ensure that hip extension is adequate as one ages. The exercise that is being presented is based on a Standing balance pose which comprehensively addresses hip stability and hip extension.

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