The purpose of this blog is to discuss the anatomy and function of the hip flexors, how you can objectively assess limitations of these muscles, and what are the best strategies for improving range of motion in this area.
If the hip flexors have decreased flexibility, they can potentially limit your available hip extension. Possessing adequate hip extension range of motion can be an important consideration for performance during various athletic activities, such as with sprinting. Additionally, it can allow you to express more movement variability or explore more movement options that you may not be able to do otherwise.
There is not a set amount of hip extension everyone should strive for, but rather how much you need is dependent on your desired activities and goals. For some, just a few degrees might be appropriate while others may benefit from more.
However, the goal should not be to improve hip extension for the sake of improving hip extension. Rather you should ask yourself, “based on my desired activities and goals, would I benefit from improving this motion?”
Finally, it should be noted that hip tightness is a subjective experience, and by itself, is not indicative of a problem. In a moment, I will review some tests used to objectively measure hip extension range of motion, but it is possible to perceive a sensation of tightness without an actual limitation in hip movement. However, if reducing or altering this sensation is important to you, then some of these same exercises used to improve hip extension may also be helpful.
Anatomy and Function
The hip flexors are a group of muscles located on the front of your hips and include the iliopsoas, rectus femoris, tensor fasciae latae (or TFL), sartorius, adductor longus, and pectineus muscles. These muscles are primarily responsible for flexing the hip.
Hip flexion is in reference to drawing the femur toward the pelvis, such as with lifting the leg, as well as moving the pelvis toward the femur, such as with tilting the pelvis anteriorly.
The most well known methods for assessing hip extension range of motion are the Thomas test and modified Thomas test.
The Thomas test is performed by lying on your back on a flat surface and pulling one knee into the chest to maximally flex the hip. This test is scored on a binary scale: either positive/negative or pass/fail. This test is deemed positive when there is a noticeable gap between the leg and table, indicating a lack of hip extension.
The modified Thomas test is similar, however it is performed on the edge of a table or surface. This test is commonly scored as pass/fail as well. If the thigh is unable to extend to a neutral position or drop below the horizontal, it is considered a positive test. But because the leg can hang off the edge, it allows for the additional measurement of an actual peak hip extension angle, as well as a knee flexion angle.
Typically, the measurement used to determine hip extension angle is the angle of the thigh relative to the horizontal, or in other words, the hip angle relative to the table. However, this method does not take into consideration pelvic positioning, which can significantly influence results.
Vigotsky et al in 2016 found the modified Thomas test has poor reference validity and reliability when pelvic tilt is not controlled, but when controlled, it becomes a valid test for evaluating peak hip extension angle. This means that in order for measurements to be more accurate, hip extension angle should be measured in reference to the pelvis, not the table. The need for pelvic stabilization is also important for minimizing error with knee flexion measurements, as shown by Kim and Ha in 2015.
In theory, assuming pelvic tilt is controlled for, the position of the leg may indicate which muscle or muscles are limited. For example, since the rectus femoris crosses the hip and knee joint, a limitation may present with more knee extension. If the knee is bent, but the hip lacks extension, it may indicate limitations of the iliopsoas muscle. However, it should be noted other structures and factors can limit hip extension, not just the muscles, so these tests are not perfect.
Static stretches, or holding one position for a given duration of time, are usually the most popular in terms of hip flexor stretches. While these can be advantageous in some cases, our preference includes dynamic stretches and eccentric strengthening for improving hip range of motion.
Here is an example of a dynamic stretch progression:
- Dynamic Hip Flexor Stretch
- Dynamic Hip Flexor Stretch with Sidebend
- Dynamic Hip Flexor Stretch with Sidebend and Rotation
If you want to bias the rectus femoris, you can try this variation:
For each of these, you can perform 10-15 repetitions on each side.
Another option is eccentric focused stretching. These move the hip through a larger range of motion at higher intensities, and in addition to improving hip extension mobility, you can also build strength and control.
Here is an example of a eccentric stretch progression:
If you want to bias the rectus femoris, you can perform this same movement with the rear foot elevated:
To further increase the difficulty of these movements, you can hold a weight.
For each of these, you can perform 6-10 repetitions on each side with an emphasis on a slower lowering (3-4 seconds).
Thank you for reading! If you have any questions, leave them in the comments below!