Gluteus Medius is a critical muscle for healthy hip function.
It's a little bit a jack-of-all-trades. Its primary role is to stabilize the hip joint, i.e. keep the femur stable in the hip socket on every step.
It is also a prime mover in hip abduction (lifting leg out to the side); and helps with hip flexion (lifting the leg forward and up), and with hip extension (opposite of hip flexion - extending the leg backward).
Basically, it moves your leg forward, backward, and out to the side - it's crazy versatile.
Glute Medius is able to accomplish all of these actions due to its width, position, and the direction of its fibers (see image).
Due to our habit of prolonged sitting, Glute Medius gets short and under-used. Over time, it weakens. And we end up with short (tight) and weak Glute Medius.
That's a recipe for injury.
Weak and unstable Glutes cause poor posture, make you wobble, destabilize the sacrum and the spine, and cause a slew of other unpleasant outcomes.
If you are a runner, it's imperative to have strong Glut Medius, especially on those long runs. If it's weak, it will fatigue and stop stabilizing the hip. This causes IT band syndrome, high hamstring tendinopathy, and occasionally back pain.
How to Fix Weak Glute Medius
The main thing to do is to strengthen it.
The problem is ... we sit too much. At work, to eat, to drive, etc.
Therefore, we need to un-do the harmful effects of sitting on a regular basis.
1. Roll the Glut Medius on a baseball, or a ridged foam roller. Hold for 15-20 seconds over painful spots. Don't roll more than 10 minutes at a time. Please note: this is not the same as rolling the IT band (rolling ITB does not achieve the same effect).
2. Get a massage with a neuromuscular therapist, or another experienced soft-tissue therapist. Your therapist should be able to examine all the fibers of the Glute Medius (anterior, middle, and posterior), determine which fibers contain chronic tension and trigger points, and deactivate them.
3. Strengthen IT
Strengthening should start right away.
Here are some of my favorite exercises for Glute Medius: