The Importance of Hip Internal Rotation
Hip joint internal rotation, sometimes referred to as medial rotation, involves the femur rotating within the hip joint toward the body’s midline. This movement also occurs when standing with a fixed lower limb while the pelvis rotates, such as when the left anterior superior iliac spine (ASIS) shifts in front of the right, or vice versa.
The “normal” value for hip internal rotation is typically 45 degrees. However, few individuals achieve this level of movement. A minimum of 35 degrees is generally considered sufficient for most people.
Why is Hip Internal Rotation Crucial?
Many people, including runners, coaches, and physical therapists, understand the importance of sufficient hip extension during the gait cycle in both walking and running. A lack of hip extension can cause significant problems, impacting athletes and non-athletes alike.
One major issue linked to reduced hip extension is gluteal muscle inhibition. When the glutes are inactive, it increases strain on the hamstrings and lumbar spine, among other complications.
However, what many people don’t realize is that adequate hip internal rotation (IR) is essential for proper hip extension toward the end of the gait cycle. Without enough IR, the pelvis cannot move forward over the stance leg, leading to a shortened stride.
In fact, without full internal rotation, the body employs various compensatory techniques that can cause their own problems, eventually leading to injury.
Common Compensations and Injuries
Individuals with a hip internal rotation deficit (HIRD) often exhibit several compensatory behaviors:
- Overpronation at the feet
- Knee valgus
- Reduced step length
- External rotation of the foot during the terminal stance phase
- Increased lumbar and knee extension
These compensations can result in numerous injuries, affecting areas from the ankle to the shoulder.
HIRD becomes even more problematic in sports and activities that require deep hip flexion (such as squatting) or rotation through the hip, pelvis, lumbar, and thoracic spine. Golf is an excellent example of such a sport.
How to Assess a Hip Internal Rotation Deficit (HIRD)
Assessing HIRD can be done in several ways, and it’s advisable to use at least two techniques to evaluate the hip joint comprehensively.
- Assess in Both Hip Flexion and Extension:
- The position of the hip affects the function of some prime movers, such as the gluteus minimus and piriformis. These muscles switch between internally and externally rotating the hip, depending on the degree of flexion.
- Assessing in flexion helps remove additional restrictions from external rotators that cross the hip joint at the front (e.g., iliopsoas, sartorius, pectineus, and adductors brevis and magnus).
- Active and Passive Assessment:
- An increase in range during passive motion suggests that weakness or inhibition in the internal rotators may be responsible, rather than tight external rotators, and vice versa.
By employing these assessment techniques, you can better determine the cause of any deficits, leading to more effective interventions and improved outcomes.
How can you reduce a HIRD?
In order to increase the range of motion at a joint, you need to focus on reducing muscle tension in the opposing muscle group — in this case the external rotators, as well as strengthening the internal rotators themselves.
Here are a couple of stretches:
Both stretches should be held for 30 seconds and repeated 2-3 times for maximal effect. This should be repeated 2-3 times a day.
And a couple of strengthening exercises:
- Reverse clam: Start in a side-lying position with both knees bent to 90 degrees and feet in line with the spine. Keep the knees together and raise the top foot away from the bottom one. Ensure the pelvis stays static throughout. For additional difficulty, add a resistance band tied around the ankles.
Perform strengthening exercises once a day at around three sets of 15 reps. Always work both sides evenly to avoid imbalances.
