The hip flexors are one of the first areas we rush to stretch since they tend to feel tight more often than any other muscle group. The problem is, tightness can often be confused for weakness and when you stretch a weak muscle you are only making the problem worse.
In the video above Jeff from Athlean-X YouTube channel show you how to determine if your hip flexors are tight or weak and the appropriate approach depending on those findings.
First we need to talk a little bit about anatomy however. If you have ever had low back pain while doing ab exercises, then you know why the hip flexors are so important. They originate on the lumbar vertebrae and can pull on your lower back when they get tight. They can also wreak havoc elsewhere when weak. Determining whether or not you are dealing with a tight or a weak hip flexor is crucial.
To start however, you have to understand that the hip flexors are not a single muscle group. Instead, there are 5 muscles that contribute to the act of lifting the hip into flexion. Three of these (TFL, rectus femoris, and sartorius) originate at the level of the hip and the iliac crest which means that they are at a mechanical advantage to lift the knee to the level of the hip but are at a disadvantage to lift them any higher. Two other muscles however (the psoas and iliac) are found at a higher origin and are capable of lifting the hip past ninety degrees.
Knowing the difference between these muscles is a crucial step in determining the right course of action once you do your tests. Speaking of the tests, the first thing you want to do is see if you have a true tightness caused by muscle shortening. To do this, you are going to perform what is called a Thomas Test. Start by sitting at the edge of a bench or box with your legs halfway over the edge. Lean back and pull both legs into your chest and be sure to flatten the lower back against the surface.
From here, slowly drop one leg while tightly hugging the other to your chest. You want to observe two things about the down leg. First, is the thigh capable of making contact with the bench and second is the knee able to bend and hang freely at 80 or 90 degrees of flexion. If you find that either of these is not happening then you will want to straighten your knee and see what happens. If upon straightening you find that the thigh goes down to the surface, then your tight rectus femoris was what was keeping the leg up and you’d want to stretch that. If the leg didn’t drop down even after straightening the leg then you are dealing with a tight psoas or iliacus that could benefit from stretching.
The key is however, many times the Thomas Test is normal but the hip still feels as if it should be stretched. This is usually due to fatigue caused by having a weak hip flexor. In this case, you want to proceed to testing your strength. You can do this by either hugging one knee to your chest while standing tall and then releasing it. If you can hold it above 90 degrees but feel a cramp in the outer hip, then you likely have a high hip flexor weakness in the iliacus or psoas. If you can’t hold it there and the first place you can gain control of the thigh is at 90 degrees or lower, then once again you likely have a weakness.
Alternatively you can place your foot on a flat surface high enough to place your knee at a starting level above the hip. From here, lift the foot while standing upright and see if you can hold it off the box for at least 15 seconds without the cramping discussed earlier. If weak, you can use this as the exercise to strengthen it and can add resistance by placing a band around your foot or ankle.