Fitness
What Muscles Does Running Work?
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Hip pain is a common complaint among regular runners, whether they are recreational, competitive, or elite runners. There are many different areas where pain can be felt and different causes. Hip flexor pain describes pain at the front of the hip. It is typically a reference to one or all of 3 specific muscles and their tendons, iliacus, psoas, and rectus femoris, which are the primary hip flexors. However, hip flexor pain can also be related to other nearby structures such as the iliopsoas bursa, which can reproduce similar pain in the same location and can become painful from similar causes. You can also read our related article Hip Flexor Pain which is more relevant to non-runners.
Hip Flexor Pain: Differential Diagnosis
As there are many causes of hip pain, getting the correct diagnosis is essential for an effective management and rehabilitation plan. The best course of action is to seek an assessment and the advice of an experienced physical therapist or sports doctor. If we only consider running-related pain at the front of the hip, there are two major diagnoses that are the most common. Hip flexor injury and femoral neck stress or full fracture. These two diagnoses need very different management and rehabilitation so correct diagnosis is essential.
For example, femoral neck stress fractures are common with running but seen more frequently with endurance runners, often related to increases in the volume of running, and may be linked with very low body weight and poor bone health. Early management of this injury will be to completely offload the leg, using crutches, and to be non-weight bearing for a number of weeks. Other common running-related fractures include Stress Fracture Shin, Navicular Stress Fracture, and 5th Metatarsal Fracture.
Hip flexor pain is more common amongst faster, short-distance runners, such as sprint athletes, and is more often linked to increases in speed, the volume of speed work, or changes of terrain such as an increase in incline running. The management for hip flexor pain is often a short period of reduced activity, followed by strengthening exercises for the hip flexor muscles. It may be possible to continue running with some modifications to training. As you can appreciate, the wrong diagnosis and therefore following an inappropriate plan for the specific injury could worsen either injury.
Hip Flexor Pain Symptoms
Symptoms of hip flexor pain are felt around the crease at front of the hip, and can be felt during or after running. Depending on the severity and irritability of the injury it may also be felt when walking and sometimes with compressive positions such as a deep squat position. Some people may feel cramping or spams of these muscles, and it can also be difficult to go up stairs or stand up from a chair in more severe cases.
Sometimes this injury can be confused with Snapping Hip Syndrome which can also affect the hip flexor.
Hip Flexor Pain Running: Who does it affect?
When related to running, hip flexor pain is most often seen with faster, shorter-distance runners such as sprinters, and rarely seen with longer-distance and endurance runners. So what is the difference and why can sprinting cause hip flexor pain?
First of all, we know from research on running biomechanics that the hip flexor complex of muscles works most during the swing phase of the running gait cycle. They work much less during the stance phase (Lenhart et al, 2014). There are major differences between the swing phase of a runner who is sprinting versus a slower runner.
Learn more about running mechanics in our related article: What Muscles Does Running Work?
Sprinting
In this image, the runner is sprinting. The swing phase is the phase of running where the leg is brought forwards, it starts as the toe leaves the ground behind the body and finishes with the knee high in front of the body. You can see this runner has a high knee that comes up in front of him at the end of the swing phase, and the leg finishes with the hip extended, far behind him.
- When sprinting the cadence, or step rate, of the runner is quicker and therefore the swing phase is faster.
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- For a faster swing phase, the hip flexor muscles must work with more force and power.
- When sprinting the stride length is longer and the hip is more extended at the start of the swing phase.
- The hip flexor muscles must, therefore, work through a greater range of movement.
- When the hip is extended there is more compression and stress on the hip flexor muscles.
Endurance Running
In this image, these runners are participating in an ultra-marathon. You can see that their swing phase is different from that of the sprinter above. They have lower knees at the end of the swing phase, and less hip extension at the start of the swing phase.
- When running slower the cadence, or step rate, of the runner is lower and the swing phase is slower.
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- The hip flexor muscles can work with less force and power to generate the swing phase.
- When running slower the stride length is shorter and the hip is less extended at the start of the swing phase.
- The hip flexor muscles, therefore, have a smaller range of movement to work through.
- As the hip is less extended there is less compression and stress on the hip flexor muscles.
Treatment and Exercises for Hip Flexor Pain
As mentioned above, treatment for hip flexor pain is most effective when active. A short period of rest or reduced activity may be needed if the area is particularly painful and irritated. In addition, in these early and more painful phases of recovery, hands-on treatments such as massage to help with pain can be helpful.
To resolve the issue if it relates to the muscles and tendons of the hip flexors is to start strengthening or loading these muscles. To avoid aggravation, early strengthening may start with the hip in some degree of flexion and in adduction or a neutral alignment but avoid hip extension and abduction. These positions should be avoided as they can compress the tendons of the 3 hip flexor muscles which can aggravate pain. In later stages of rehabilitation, a gradual introduction of strengthening through extension and abduction can be done. Here are 3 exercises that strengthen the hip flexor in order from early stage to later stage rehab.
1. Hip Flexion Bent Knee
Standing with a resistance band around your ankles, and keeping your bent knee, flex from the hip to raise your knee forwards. This can be progressed by raising the knee higher or increasing the resistance of the band.
2. Hip Flexion Straight Leg
Standing with a resistance band around your ankles, and keeping your knee straight, flex from the hip to move your leg forwards. This can be progressed by raising the leg further or increasing the resistance of the band.
3. Hip Flexion from Lunge
Starting in a lunge position, come up into standing bringing the back leg forwards to finish in hip flexion, as in the first image. This can be progressed by using a resistance band around the ankle of the back leg.
In addition to strengthening the hip flexor muscles, strengthening surrounding muscles can be very helpful. The adductor longus can also work as a hip flexor so should be incorporated into rehab programs. Additionally having good strength through the abdominal and trunk muscles can prevent the hip flexor muscles from working excessively. The hip flexors can work to support the function of these muscles and compensate for poor stability through complex movements such as running.
Return to Running
This is a common injury in runners and they will be keen to resume their normal training as soon as possible if they have needed to modify training for their recovery. Returning a runner to their usual program should be gradual, a lot of attention should be paid to how the runner feels during, straight after, and the day after runs. Minor symptoms such as feelings of stiffness in the area, with no pain, can be an indicator that the individual is at the limit of their capacity, and progressing further at this time may not be appropriate. Particular caution should be taken with, incline running, higher speeds, and the volume of work done at high speeds and on an incline.
Physiotherapy with James McCormack
This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments.