Why certain hip flexors are important and how to anchor them
When dealing with knee pain, it helps to understand that muscles need anchoring in order to function effectively. One set of muscles that, when not anchored effectively, can cause knee pain are the long hip flexors. Detailed below are why you might want to anchor them, and how to go about doing it.
If you've ever looked at a digging machine or back hoe, notice how every part of the machine is in service to the bucket at the end of the arm. And actually, it would be better to say, that the machine as a whole is designed to serve the idea of digging up bucket loads of dirt and moving it. (Or if a jack hammer is attached, then the machine as a whole works towards breaking up concrete.)
For whatever reason, when we have knee problems, we tend to focus on the joint in question, the knee joint, and ignore the idea that the knee is part of a mechanism designed to transmit force from the hip to the foot (and potentially vice versa). However, the knee is part of a system that originates at the torso and ends at the foot. The knee transmits forces from the torso to the foot (and vice versa.)
And so if you have knee problems a good place to look is the hip, but you can also look at the foot. And actually, you can also look at the ribcage. (See this article Your knee, spine, ribcage and mood for why you might want to look at it and your spine when dealing with knee problems.)
Knee anatomy, connecting the hip to the foot
The idea of the knee acting as an intermediary between the hip and the foot is actually reflected in the muscular anatomy that connects to the knee.
While single joint muscles like the vastus muscles, the popliteus and the short head biceps femoris are important for knee function (of the top of my head those are the only single joint muscles that act on the knee), there are a plethora of knee muscles that attach from the lower leg (which has two bones, the tiba and fibula) to the hip bone.
More tellingly, these muscles attach from the lower leg bones to the corner points of the hip bone. And apart from the rectus femoris, these muscles all attach to either the inner or outer aspect of the lower leg.
The rectus femoris is the only one that runs across the front of the knee joint (and that's one reason that bent knee hip flexor stretches like couch stretch work mainly to lengthen or stretch that muscle.)
Shin rotation relative to the femur and/or hip
These muscles can act from a stabilized hip bone to control rotation of the shin relative to the thigh and hip.
If any of these muscles aren't working properly then you reduce controllability of the shin relative to thigh and hip bone. And your knee joint may suffer (or give you pain signals) as a result.
Note that if the knee is straight, then the shin can't rotate and so these muscles then can help control rotation of the thigh as a whole relative to the hip bone.
Shin rotation relative to the foot
Muscles that attach from the lower leg bones to the bones of the feet and toes can be used to rotate the shins relative to the feet or to shape the feet with respect to the shins in the process helping to control the ankles and feet.
Working from the hip a stabilized hip downwards, shin rotation can be controlled or stabilized giving muscles that work from the shin on the ankles and feet a stable foundation from which to work.
The knees are the intermediary.
A basic principle of muscle control
A basic principle of muscle control is: any muscle needs a stable foundation or anchor point to function effectively. If trying to deliberately control a muscle one of the first things you can do is provide anchoring for one of the end points of the muscle that you are trying to control.
Going back to those muscles that work on both the knee and hip joint, three of them, the sartorius, rectus femoris and tensor fascia latae all attach at or near the ASICs, the front point of the hip bone. Another sometimes hip flexor is the gracilis which attaches to the pubic bone.
The gracilis could help in hip flexion is the hip is extended. However, if the hip is flexed, then it may actually help to extend the hip. But rather than worrying about whether or not either is true, I'd say you'd be better of learning to feel and control your gracilis, and all the other muscles mentioned, so that you can turn them on and off at will. You can then notice the affects and respond accordingly.
How do you anchor these muscles so that they can work effectively on the knee and possibly alleviate knee problems? By creating an upwards pull on the ASICs and pubic bone.
An elegant solution to anchoring the hip flexors that act on the knee
You could try using the external obliques and rectus abdominis to pull upwards on your ASICs and pubic bone. However, you can also use your transverse abdominis.
Using your Transverse Abdominis
Using your transverse abdominis to pull the belly inwards, past the border of the ribcage and hip bones, then you lengthen the obliques and rectus abdominis. This in turn causes these muscles to activate to resist lengthening. In the process they create an upwards pull on the ASICs and the pubic bone. You thus help to anchor the upper attachment points of the aforementioned hip flexors.
Using your obliques and spinal erectors
Note that if you do choose to focus on using your obliques and rectus abdominis, one way to get a stronger activation is to exert them against your spinal erectors, particularly the iliocostalis and longissimus, both of which have attachments to the backs of the ribs.
One simple method for activating these muscles is to create a downwards pull on the backs of your ribs.
You could try combining this activation with activation of your transverse abdominis.
Pulling upwards on your ASICs
If you have reasonably good function in the above muscles, a simple way to anchor the aforementioned hip flexors is to simply create an upward pull on the ASICs (and pubic bone). You may fiind that your belly automatically pulls inwards. You may also find that your front ribs automatically lift.
Pulling down on your sitting bones
The sitting bones are located on the opposite side of the hip joint from the ASICs. An additional way to create an upward pull on the ASICs is to create a downward pull on the sitting bones (and optionally, the PSICs). How do you create a downward pull on the sitting bones? By using your hamstrings. As for the PSICs, you can create a pull on them by using your gluteus maximus.
Published: 2020 06 15
Updated: 2023 01 11
Hi, I'm Neil Keleher.
I have a degree in Systems Design engineering. Before that I served in the British army for five years. My main job was fixing guns.
I've been teaching yoga for about twenty two years now. I also do a lot of programming in python and node.js.
One of my other main projects is studying Chinese, but it's been hold while I developed tools to make studying easier. One of those is a Chinese character dictionary and the other is a Chinese word and phrase dictionary.
Both include a lookup system for Chinese characters that is foreigner friendly and that I'm proud to say that I designed.