All About the Hips: Flexion

This blog is part of the series about the hips.

The first movement of the hip we will examine is flexion. Technically speaking, flexion is movement in which the anterior surfaces of the limb move toward each other. Simply put, it is when the thigh moves closer to the upper body. 

The hip flexes often. When we walk, jump or run, our hips flex and extend over and over again. This is a natural movement and one that isn't difficult for our body to comprehend. ​Let's look at the muscles in the body that make this motion possible. 

Muscles of Hip Flexion
It should come as no surprise that the hip flexes by way of the hip flexors. We have five hip flexors. They are: the iliacus, the psoas, the rectus femoris, the sartorius, and the tensor fascia latae (TFL).

The TFL is a small muscle that is mostly used for stability. As the name suggests, it works to tense the fascia. We won't address it in detail here but let's look at the other four. 

Leg Lift requires engagement of the hip flexors.

The psoas attaches to the lower spine, and weaves down the inside of your pelvis to where it attaches on the inside of your femur (leg bone). The iliacus is very similar to the psoas. It attaches to the inside of your leg bone but only goes up half as far as the psoas. The iliacus attaches to the inside of your pelvis. The psoas and the iliacus work together to form the iliopsoas. ​Together they flex the hip. 

The rectus femoris is one of the quadriceps muscles. It is the only one to cross the hip. In this way it serves as a hip flexor whereas the other quadriceps only affect the knee joint. ​​

Finally, the sartorius is a very long and thin muscle that runs from the pelvis to the tibia (shin bone). It is the longest muscle in the human body! It is perhaps the lesser known of the "hip flexors" but can play a moderate role in flexion. ​

Should we practice this?
Hip flexion and its partner, extension, are the most natural of the movements of the hip.

​We flex the hip on a regular basis, though often with the knee flexing at the same time. In other words, the knee and hip usually bend at the same time. Think of walking or skipping. When the knee lifts in front of you to take a step, the hip and knee flex. Because these are common movements in the body, we don't need to overdo this action in our posture practice. ​​​

This position is similar to the Leg Lift and also requires strength in the hip flexors.

The muscles that flex the hip are not huge, powerful muscles. Aside from addressing any significant imbalance, it is not particularly useful to focus on strengthening this part of the body. Instead it's usually worthwhile to work on developing the muscles that extend the hip. This will help lengthen the hip flexors. 

In day to day life, the hip flexors are often in a shortened position. This has to do with how much we sit on a regular basis. When we sit, the hip flexors are short and they tend to stay that way even when we try to lengthen them. Back discomfort often comes from tight hip flexors (the psoas in this case). Tight hip flexors can also keep us from back bending affectively.

One good position to remedy tight hip flexors is a Lunge. In a Lunge, the hip flexors of the back leg lengthen. In the next blog we'll look at the muscles and postures of hip extension in detail. We'll also explore why it is a good idea to strengthen the muscles that extend the hip and what postures do this. ​

The hip flexors of the back leg are lengthened in a lunge position.