Hip Flexor Tightness Linked to Chronic Injuries in Student-Athlete Runners
by Joy Kamani
By Victor Romano, MS, ACSM-cPT
When you run the body's complex system of muscle, tendon and ligament springs behave like a single linear spring, which is known as "Leg Spring" theory. The leg acts as a linear spring during running and hopping and adapts to the stiffness of the running surface, maintaining constant stiffness of the leg-surface system. If there is an imbalance in the length-tension relationships and improper dynamic posture during movement, the constant tug of war between muscles can prematurely lead to muscle, joint, tendon and ligament injuries.
If a muscle is shortened for a prolonged period of time, it will become tight. When a muscle is tighter than it should be, it not only affects the opposing muscle but can have repercussions on the entire musculoskeletal system. This is a huge problem with student athletes, who are seated for a large percentage of their day. If a runner continues to exercise with poor posture, the muscle will tighten and strength will become imbalanced. The body will recruit the wrong muscles causing it to develop disproportionately, which can cause chronic injuries. You can start to understand where these imbalances stem from and how easily avoidable they are.
Proper running posture consists of a slight forward lean and anterior pelvic tilt. An excessive forward lean while running suggests that the posterior chain muscles (hamstrings, gluteals, and erector spinae) are not strong enough, which increases strain on the hamstrings and back during the running action. A posture that is too upright indicates exaggerated pelvic anterior-posterior (A-P) tilt, meaning the gluteals and abdominals do not have the strength to control the pelvis adequately during landing. An excessive anterior pelvic tilt increases the ground impact through the lumbar and sacroiliac joints and forces the knee to internally rotate, which in turn may increase the pronating forces on the ankle. An exaggerated pelvic A-P tilt can have negative effects on other muscles.
The most common side effect is a tightened piriformis and hip adductor complex. The piriformis is a deep muscle and is the most powerful external rotator of the hip. A tight piriformis can lead to problems with the knees and piriformis syndrome. Piriformis syndrome occurs when the piriformis irritates the sciatic nerve and causes a deep shooting pain from the buttocks down the back of the leg. A tight piriformis is more common in men because men tend to sit with their legs spread apart.
The adductor complex is the group of muscles that squeeze your legs together. The adductor muscles commonly develop tightness in the bottom of a squat in which the hips are almost fully flexed. Tight adductors can cause the femur to become internally rotated, which will most likely lead to kneecap pain because the joints of the knee will no longer align properly. Tight adductors can be frequently identified by a knock kneed appearance. Tight adductors are most often associated with women, who tend to sit with crossed legs. Women who wear high heels are also prone to tight lower leg muscles including the gastrocnemius, soleus, and peroneals. Tightness in these muscles can be identified by flattened and externally rotated feet. Tightness in the lower leg muscles can also lead to plantar fasciitis.
Both the piriformis and adductor complex have a unique quality to them; they both rotate the femur either internally or externally, a bad combination when mixed with tight hip flexors. Tight hip flexors are a major cause of many posture problems. The main purpose of the hip flexor is to bring the thigh up towards the abdomen. When the hip flexors are excessively tight they cause exaggerated pelvic anterior tilt. The lumbar spine becomes excessively arched and the thoracic spine develops a kyphotic (rounded/hunch back) alignment, which can also lead to forward head posture. Tight hip flexors can begin to do the abdominals' work, and make it almost impossible to benefit from some abdominal exercises. Tight hip flexors cause the primary hip extensors, the gluteal group, to become lengthened and weak because of their agonist-antagonist relationship, which means the glutes and hip flexors are opposing muscles. When the primary hip extensors become extremely weak, the smaller assistor muscles take over causing further problems. In men, the combination of a tightened piriformis or hip adductor complex with tight hip flexors will cause the femur to be elevated and rotate externally. In woman, the femur will be elevated and rotate internally. Most runners will see a difference in the length of the legs from the variance of tightness in each hip flexor. A functional leg-length discrepancy isn't painful in itself, but it can cause other problems and injuries.
Leg-length discrepancy is a causing factor in the development of a variety of overuse injuries because it alters the magnitude and distribution of mechanical stress on the body while running. The center of gravity changes as weight is transferred to one side of the body. That side will undergo more stress and eventually, compensatory changes will take place above the pelvis as the balance of the spine is altered. The most common injuries related to leg-length discrepancies are: tibial stress fractures, patellofemoral pain syndrome (Runners Knee), iliotibial band friction syndrome, patellar tendinopathy (Jumper's Knee), low back pain, hip pain and vertebral disk pain syndrome.
WAYS TO CORRECT MUSCLE IMBALANCES
If you have muscles that are chronically tight, corrective flexibility exercise is a direct approach. You should perform these corrective flexibility exercises daily if possible.
Self-Myofascial Release (SMFR): Self-Myofascial Release is a form of massage that allows you to release the tension of your muscles by yourself. The best way to perform self-myofascial release is with a foam roller, but you can also use a massage ball, a medicine ball or even a hard ball. Place the tight body part on the foam roller. Apply pressure to the entire length of the muscle with the foam roller. Apply pressure to the tenderest spots for 20-30 seconds each. Make sure you perform each session on the foam roller before your static stretching.
Static Stretching: Static Stretching is the classic stretching technique and is used to help correct posture problems most efficiently. Hold your body in the position of "slight discomfort" for at least 20 seconds.
Active Isolated Stretching: The Active Isolated Stretching technique involves holding each stretch for only two seconds. This method of stretching is also known to work with the body's natural physiological makeup to improve circulation and increase the elasticity of muscle joints and fascia.
Simple body weight exercises can be used to help eliminate any muscle imbalance that a student athlete might have. Main areas to concentrate on are the abdominals (upper and lower, internal and transverse), hip abductors/adductors, glutes (maximus, medius, and minimus), erector spinae, and calf muscles (gastrocnemius, soleus). To do this, concentrate on completing a high number of repetitions. Start with 15 per leg per exercise and work your way up to 50.
A massage therapist will use hands-on techniques including specific joint mobilization, manipulation, or soft tissue stretching to address any imbalance. A massage therapist can also prescribe specific exercises to help correct any imbalance.
Leg-length analysis can be used as a reliable indicator of nervous system involvement. Subluxation of the spinal bones causes a compensatory "functional" change in the length of a person's legs, and a chiropractor can use leg-length analysis to identify the imbalance and determine an appropriate corrective protocol.
Footwear does influence the impact and muscle stiffness to the lower extremity during running. It is best to replace running shoes every 4-6 months depending on mileage. A difference in shoe cushioning properties does not appear to be significant when deciding what type of shoes to wear. It is best to consult a running shoe specialist before purchasing shoes.
The relationship between biomechanics and injury is specific to each body part. Overall, poor mechanics of any body part will either increase the landing forces acting on the body or increase the work to be done by the muscles. Both increase the level of stress, which — depending on the individual and the amount of running — can become excessive and cause injury.
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- Cavanagh, P. (1990), Biomechanics of Distance Running. Human Kinetics.