You can tell if you have weak hip flexors by doing simple tests like the leg raise hold, by struggling to keep your knee lifted to your chest without dropping.
Sit with your lower back against the wall, then lift one thigh towards your chest as high as you comfortably can, then try to hold it their for 15 or more seconds without your foot dropping or your back arching.
And if you have difficulty holding the position or the leg drops quickly then it's a sign of weak hip flexors.
Lack of hip mobility can cause back pain as lack of hip mobility is a major cause of lower back pain, because lack of hip mobility forces your lumbar spine to compensate for the restricted movement, which leads to increased stress and muscle imbalances as well as potential injury.
And when your hips are tight, particularly in the extension and rotation, your lower back works harder which results in pain.
If your hips are not able to move properly during daily activities or during exercise, your lumbar spine will compensate by rotating or bending more than it normally should, which causes strain.
Having good hip mobility is also crucial for the expression of normal low back function, which is mainly because of how close they are together.
To test for internal hip rotation you can use the Seated Hip Rotation test.
To test for the internal hip rotation using the seated hip rotation test, sit tall on a chair edge, which your feet dangling and your knees at 90 degrees.
Then keep your torso still and lift one foot slightly and rotate the foot and lower leg outwards, "internally rotating the femur" as far as possible.
And observe.
Aim for around 30 degrees of outward rotation, if limited it then suggests tightness or weakness.
Some reasons for your hips not having any internal rotation are from chronic tightness in your external rotator muscles, like your piriformis muscles, a stiff posterior hip capsule, weak internal rotator muscles or TFL/adductors and even due to structural limitations like bony impingement.
Even prolonged sitting or prolonged standing with excessive external rotation, "toes out" are also common and primary causes of having no hip internal rotation.
Muscles like your piriformis and deep glutes become overactive and lock your femur in an outwardly rotated position and even a tight rear hip capsule can restrict the joint from allowing your femur to glide backward, which is required for internal hip rotation.
Also the muscles that are responsible for internal rotation of the hip, like the Tensor Fasciae Latae and adductor muscles are also often underused or even too weak to counteract the tight external rotators.
When hip rotation is missing , the knees also often absorb the rotational force, which can lead to pain, or it can also contribute to lower back issues.
The nerve that controls hip internal rotation is the superior gluteal nerve (L4–S1).
The hips internal rotation is controlled mainly by the superior gluteal nerve (L4–S1) nerve, which also innervates the gluteus medius, the gluteus minimus and the tensor fasciae latae.
These muscles are also responsible for rotating your thigh inward.
Other nerves like your femoral nerve, via pectineus may also assist n internal hip rotation.
The superior gluteal nerve (L4–S1) is what innervates your gluteus medius, gluteus minimus and tensor fasciae latae, which are the key internal rotators.
And the gluteus minimus, "anterior fibers", gluteus medius, "anterior fibers, and the tensor fasciae latae are what perform hip internal rotation.
And the assistant nerves like the obturator nerve also helps to stabilize, while your anterior femoral nerve branches provide additional muscular support for internal rotation.
The hip internal rotation, is the inward twisting of the thigh bone, also known as the femur within the hip socket.
Hip internal rotation is also crucial for daily movements like squatting, walking and even pivoting, which allows for smooth gait and prevents lower back pain and knee pain by moving your foot inward relative to your body.
Having limited internal hip rotation, which is often due to tight hip capsules or weak rotators leads to compensation as well as causes pain and dysfunction and improving it involves using targeted stretching and strengthening exercises to regain motion once again.
The reason hip internal rotation matters is because it allows for movement and allows for you to rotate your thigh bone or femur towards your body's midline.
Internal hip rotation has a normal range of around 30 to 46 degrees, which is essential for stability and alignment and it allows you to put on shoes, walk, climb stairs, play sports and sit comfortably.
The consequences of a lack of internal hip rotation are back pain, knee pain, "knees tracking inward" shorter strides and flat feet.
Common signs of limited internal hip rotation include knee pain, lower back pain, feet turning inwards when walking and difficulty in squatting deeply.
To improve your internal hip rotation you can do some exercises like quadrupled band assisted internal rotation, face down feet opens, side planks and stretching.
For stretching, focus on creating space in the back of your hip capsule.
Doing side planks can improve mobility and strength in supporting the muscles.
For face down feet opens, lay on your belly, knees bent, lift your knees and then splay feet out and in and rotate your thighs inwards.
For Quadrupled band assisted internal rotation, lay on your hands/knees with a band around your ankle and then rotate your foot inward against the resistance.
Cause of limited hip internal rotation include sitting too long, tight hip capsule and overactive external hip rotators.
And so improving your hips internal rotation can help the body move more efficiently and reduce strain on your lower back and knees and prevent injury and improve overall function.