INTRODUCTION
It is important for athletes to have strong hip muscles that will provide forceful movements in 3 degrees of freedom: flexion/extension, abduction/adduction, and internal rotation/external rotation. It is also important that these muscles are strong to stabilize the pelvis, which will allow a stable foundation for lower extremity kinetic chain movements. An unstable hip can cause serial distortion patterns, which are predictable patterns of dysfunction throughout the kinetic chain that lead to inevitable injuries. For example, a weak gluteus medius can increase the stabilizing role of the tensor fasciae latae (TFL). The increased stabilizing demand placed on the TFL leads to tightness in the iliotibial (IT) band, which can then lead to the development of IT band friction syndrome (2). A weak gluteus medius can lead to an increase in the dynamic Q-angle, which is the line of pull of the quadriceps muscle group during lower extremity closed kinetic chain movements. This increased dynamic Q-angle can put the anterior cruciate ligament at a greater risk of injury during landing (3) or can cause patellofemoral tracking problems that may lead to chronic injuries, such as chondromalacia patella (1,4).
Agonist and antagonist strength balances are also important to prevent injuries. Due to common resistance training practices, the hip extensors become much stronger than the hip flexors. This imbalance can lead to hip flexor strains and also to a posterior pelvic tilt, which increases lumbar lordosis putting the lumbar spine at a greater risk of injury (5). Strength balance ratio between the hip adductors and abductors is also important. Research has demonstrated that hockey players are at much greater risk of groin strains if adductor strength is less than 80% of abductor strength (7). Therefore, comprehensive strengthening is extremely important for injury prevention.
HIP STRENGTHENING CHALLENGE
A healthy balance of hip strength is important to ensure stability and prevent athletic injuries. Achieving this balance is a difficult task even in a setting with an informed strength coach and a motivated athlete. One reason for this challenge is that popular strength and power lifts, such as the squat, olympic-style lifts, and lunges, primarily train the hip extensors (hamstrings and gluteus maximus). These are very large muscles that play an important role in many athletic movements, such as jumping, sprinting, and coming out of a sports stance. It is understandable that athletes would focus on these muscles and that equipment manufacturers would design a variety of equipment for strengthening the hip extensors. However, the result is that athletes focus primarily on 1 of the 6 hip movements and tend to neglect the muscles responsible for the other important hip movements.
In most strength and conditioning facilities, athletes will have access to a standing 4-way hip exercise or a seated abduction/adduction machine. However, the reality is that these devices are not commonly used especially by male strength and power athletes. To our knowledge, there is no strength training device that is designed specifically for internal and external rotation of the hip. Therefore, many athletes rely on isometric actions of the hip stabilizers during hip extension exercises to strengthen the muscles active during frontal and transverse plane movements. And some athletes rely on strengthening internal and external rotators by activating them during another movement to which the muscles also contribute. For example, the gluteus maximus is the prime mover for hip extension and also contributes to external rotation. But ideally resisted external rotation would also be included in the strengthening program.
RECOMMENDATIONS FOR STRENGTH AND CONDITIONING PROFESSIONALS
The responsibility of comprehensive hip strengthening often falls on those working with athletes in a rehabilitation setting after injury has occurred. However, to prevent injury and improve performance, exercises to strengthen all hip musculature in a dynamic fashion can be easily completed in the strength training facility under the supervision of the strength coach. The following strengthening exercises are recommended to ensure strength balances and to avoid neglecting important hip muscles and movements. The strength coach can either provide resistance manually, teach athletes to provide resistance for their peers, or use elastic bands, elastic tubing, or cables to provide resistance as is shown in Figures 1–4. The anatomical movement and muscles that are activated are included in Table 1 (6). Because it is difficult to achieve high intensity with manual resistance or with elastic tubing, higher repetitions should be used. Three sets of 10–15 repetitions during 3 days per week are recommended.
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Table 1: Hip muscle anatomy
Figure 1: Hip external rotation with resistance provided by elastic tubing: (a) starting position and (b) ending position.
Figure 2: Hip internal rotation with manual resistance: (a) starting position and (b) ending position.
Figure 3: Hip adduction with manual resistance: (a) starting position and (b) ending position.
Figure 4: Hip abduction with resistance provided by elastic tubing: (a) starting position and (b) ending position.
RESISTANCE DURING COMBINED HIP MOVEMENTS
Lower extremity Proprioceptive Neuromuscular Facilitation (PNF) patterns can also be used to simultaneously train muscles in each of the 3 planes of movement, but these techniques require advance training and expertise. Since hip flexion is commonly neglected during resistance training, the 2 flexion patterns are included in Figures 5 and 6. The name of the PNF pattern along with the anatomical movements for the hip is included (5). To accomplish the resisted movement, the strength coach should position the athlete as shown in the photographs to the left in each figure, with hand placed about the knee and foot as shown. The athlete is then instructed to move to the position shown in the figure to the right while the strength coach provides appropriate resistance so that a concentric action can be completed. From this position, the strength coach can force the athlete back to the original position while the athlete resists this movement, achieving an eccentric action. This process is then repeated until the desired repetition numbers have been achieved.
Figure 5: Lower extremity D1 flexion—hip flexion, hip adduction, and hip external rotation: (a) starting position and (b) ending position.
Figure 6: Lower extremity D2 flexion—hip flexion, hip abduction, and hip internal rotation: (a) starting position and (b) ending position.
MODIFIED TRADITIONAL EXERCISES
The traditional lunge exercise involves extension of the hip, knee, and ankle in a fashion similar to the squat and leg press. However, the lunge can be modified to incorporate other hip musculature. Lateral lunges include hip adduction in addition to hip extension. If a kicking motion is added to the concentric phase of the lunge exercise, the hip flexors can be included in the forward lunge and the hip adductors in the lateral lunge. However, it should be noted that these movements only occur against the resistance of the athlete's limb.
RESISTANCE DURING FUNCTIONAL MOVEMENTS
Lower extremity resistance training using elastic tubing during single planar and multiplanar functional activities can also be utilized. The use of an elastic band secured around both ankles to apply tension to both limbs during a lateral shuffling drill with the hips flexed beyond 45° and the knees flexed to 90°, or forward stepping at a 45° angle in the same hip and knee position, will require both concentric and eccentric muscle actions of the hip musculature in both limbs. The key to this exercise is having the athlete maintain tension and hip and knee flexion during the entire exercise. The exercises should be done over a distance of 15–20 yd and then repeated for multiple repetitions.
CONCLUSION
Current hip strengthening practices emphasize the hip extensor muscles and neglect other hip movements and muscles. This leads to weakness in important hip muscles, strength imbalances, and dynamic instability. Working with athletes, strength coaches can ensure comprehensive hip strengthening by designing exercises that strengthen all 6 movements that occur at the hip. Hip strength training can be augmented with manual resistance or resistance provided by elastic bands, combined movement pattern exercises, such as PNF patterns, and resisted functional movements. This type of training will ensure a stable hip and strength balance that will lead to proper lower kinetic chain movements that will lessen the likelihood of injury.
REFERENCES
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