In strength and conditioning for sports performance the hip flexors are historically one of the most ignored muscle groups. As sports grow increasingly competitive, focus has remained on muscles that are responsible for propelling the body forward; like the quads, hamstrings, and calves do in running and jumping. It is only recently that the hip flexors have gained part of the attention they’re due. In this program we’ll take you through all aspects of training to unlock your hip flexors full potential, to include: stretching, strength training, neural tension, balance, and injury prevention.
Stretching Tight Hip Flexors
The Iliopsoas is the muscle that is commonly referred to as the hip flexor. It is formed when 2 separate muscles, the iliacus and the psoas meet. Both muscles have fibers that originate from different points, but these fibers come together to attach at the same insertion and together they form the largest hip flexor in the body. It produces great power, but limitations present in this muscle can go beyond postural deficits.
Tight hip flexors don’t just tilt your hips forward, they can decrease neural drive to the hip extensors, specifically glut max. As the hip flexors become restricted they’re also over activated and by reciprocal inhibition can decrease the neural drive to glut max. In the presence of tight hip flexors, glut max activation has been found to be 60% less.
As neural drive to glut max decreases, secondary hip extensors like the hamstrings and adductors pick up the slack to produce the required hip extension torque, this is known as “synergistic dominance.” In the unrestricted hip flexor, activation of the glut max will be 2.3 times greater than the hamstring (biceps femoris). In the restricted hip flexor, this number drops to 0.88, indicating greater activation of the hamstring than the glut max. As this dependency on the secondary hip extensors increases, greater tissue stress is incurred and risk of injury rises.
Furthermore, tight hip flexors will not allow for the optimal hip extension in the push off phase of running. This decreases force production and hampers running efficiency. Although the hip flexors aren’t one of the prime movers in propelling the body forward, restrictions of the muscle will have deleterious effects on the ones that are, and will compromise sports performance anyway.
Before learning how to stretch hip flexors the Thomas test should be utilized. This is a quick and easy way to assess if you have tight hip flexors or if the restriction lies in the quad. The results of the Thomas Test are important because it will indicate how to stretch hip flexors. In this test the subject lays supine (on their back) with their butt at the end of the table. One knee is flexed to the chest and held at end range. The opposite leg remains relaxed and should stay flush with the table, if the hip flexor is not restricted. The bottom of that thigh will rise off the table and a stretch will be felt by the subject if hip flexor restriction is present.
The next part of the test is critical to determine your form on how to stretch hip flexors. Either of the following 2 conditions will indicate restriction of the rectus femoris: the relaxed leg lowers to the table when that knee is extended or the relaxed leg hangs straight during the test and the knee is not bent. If the thigh is still raised off the table after the knee is extended, then the iliopsoas is tight.
It’s so important to determine the results of the test because rectus femoris is the only muscle of the quad that crosses the hip, and it also crosses the knee. So, if you’re always stretching your hip flexor with the knee bent you’re also stretching rectus femoris. In order to isolate the iliopsoas the knee must be straight when the stretch is performed.
This can be done on your TherRexTM Board by laying prone on the floor with one thigh on top of the board and the front of your hip firmly on the ground. Start with your thigh between the footprints for a more gentle stretch, then turn the board 90 degrees to progress the stretch. Throughout the stretch the front of the hip should stay on the floor to prevent compensation. The stretch intensity can be increased by pushing down on the board at the foot. This tilts the board and raises the thigh to increase the stretch felt on the hip flexor. This will truly isolate the hip flexor. Alternatively, the knee can be bent bent in this position if rectus femoris stretching is needed. Traditional hip flexor stretching as shown below can be done, but stretching rectus femoris will prevent isolation of the iliopsoas. After muscular restriction is relieved it’s important to do the same for the nerves.
Nerves can become restricted just like muscles can and mobilization of the femoral nerve is essential to fully unlock the hip flexors. A chicken and egg scenario is present in the relationship between a restricted femoral nerve and a tight hip flexor. It’s currently unclear which causes which, but the benefits of a hip flexor stretching program could be quickly undone if femoral nerve mobilization is excluded.
To determine the inclusion of nerve mobilization into a stretching program, you can test for Adverse Neural Tension (ANT) in the femoral nerve. This can be done easily through the Prone Knee Bend (PKB) test. This test is completed by having the subject lay prone (on their stomach) and the knee is passively flexed to end range. Pain on the anterior thigh is indicative of increased neural tension. In this test, pain can also be caused by a strained quadricep. Pain before reaching end range in the PKB test is linked with greater hip flexor deficit in the Thomas test.
Nerve gliding can safely be done independently to decrease tension on the nerve. To glide the femoral nerve the subject lays prone with their arms bent and propped on their elbows. Both legs stay straight and one legs is raised up in the air. As the leg is raised the subject brings their chin to their chest, as the leg is lowered the subject tilts their head back. This simple movement will glide the femoral nerve and decrease any tension that is on it. Unlocking your hip flexors has been exclusive to mobility training, but strengthening these muscles can further improve sport performance.
The iliopsoas is the prime mover in hip flexion, but there are other muscles that assist in this movement. The sartorius and the tensor fasciae latae act in hip flexion, but as the hip moves further into flexion the action of these muscles decrease and the workload of the Iliopsoas increases. This makes the Iliopsoas increasingly more important as the hip is naturally moved through out its range. This comes into play when running, one of the biggest keys to sport performance.
Although the hip flexor does not play a primary role in active propulsion, as the quads or hamstrings do, it is responsible for bringing the leg forward through the air in running after the toe leaves the ground. A weak hip flexor will not perform this movement efficiently, as a result running speed and running economy decline. Hip flexor strengthening exercises alone have shown to decrease 40 yard dash times by 0.233 seconds. With the skill and competition levels rising each year, that’s more than enough reason to add hip flexor strengthening exercises to your current workout routine. There’s obviously an edge to be gained in speed training, there’s one to be gained in balance training as well.
Balance and Injury Prevention
Increased strength of the hip flexors has been shown to improve balance scores and decrease the risk of injury. In the star excursion balance test (SEBT) the subject stands on one foot and reaches the opposite foot out as far as they can in each direction until they complete a star pattern on the floor. Weight is not put through the moving foot, the toes gently touch the floor and the foot returns to the center before moving to the next point. The subject should be able to reach lengths of greater than 94% of their leg length. Distances less than 94% of leg length have shown a 6.5 times greater risk of leg injury. Subjects with greater hip strength show better
SEBT scores. In particular increased hip flexor strength is associated with improved balance in the anterior and posterolateral directions (forward, back and to the side). This type of balance training can increase SEBT scores by 11-35% in just 2-4 weeks and has been shown to increase speed, agility, and acceleration. All of which are vital to successful sports performance. And after you’ve stimulated the hip flexor to improve performance, you can use this trick to decrease it’s substitution pattern during your ab routine.
In performing a traditional sit up with the knees bent and feet on the floor the hip flexor pulls on its origin at the lumbar spine which causes lumbar hyperextension and compresses the intervertebral disks, leading to increased risk of permanent injury. This can be corrected by lifting the feet off the floor and raising the knees until they’re perpendicular to the floor. This tilts the pelvis posteriorly (backwards) and shortens the hip flexor which decreases its activation and increases activation of the abdominals. Making this small modification increases activation of the rectus abdominis by 57%.
Alternatively, the Janda sit up can also be performed. In this method the hips are flexed and resistance is applied to the heel area either by a partner or by a piece of immovable equipment. The subject uses their hamstrings to contract against the resistance while they use their abdominals to perform a sit up. By activating the hamstrings, activation of the hip flexors is reduced by reciprocal inhibition. This method produced the highest muscle activity of the rectus abdominis, 70% greater than the traditional sit up.
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