Introduction to the Hip

The hip is the most important, yet overlooked, joint in the body. Keeping your hips working correctly is of paramount importance to overall body health. Unfortunately, talking about the hip can be confusing because the term can refer to both the joint itself or the muscles that surround it. As you will see over a series of posts, understanding this important joint, and the muscles that move it, could be the key to restoring lost mobility and banishing pain.

hip joint

The right hip joint.

photo credit: Blausen 0488 HipAnatomy” by BruceBlausOwn work. Licensed under CC BY 3.0 via Wikimedia Commons.

First, we have the hip joint, a synovial ball and socket joint which connects our femur (upper leg) and pelvis, effectively joining our upper body and lower body. “Synovial” simply refers to the fact that the joint has a capsule. Inside the capsule is fluid that keeps the joint lubricated. The capsule attaches onto both the pelvis, and the femur.

It is strong but relatively loose. This looseness makes the hip joint the second most movable joint in the body. Only the shoulder permits more range of motion. This is a very important point to remember. The hip joint is inherently mobile! When the hip isn’t mobile, problems ensue.

There are some naturally occurring restrictions upon mobility, however. Ligaments connecting the pelvis and femur are found outside the hip capsule which limit range of motion in one plane of motion or another. We generally think of joint range of motion as a good thing, but too much laxity can cause problems, too. There is nothing advantageous about having flexibility without strength. The ligaments provide strength and stability to an otherwise very movable joint.

The hip joint performs two primary movements that are very common to exercise, flexion and extension. If you do a squat, you flex your hips as you descend and then extend the hips on your way up. The other movements of the hip are vitally important to maintain proper function yet are generally an afterthought: internal and external rotation, abduction and adduction.

Deficiency in any of these hip movements can lead to pain and injury, and not necessarily to the hip. For example, you might experience pain or injury in your knees or lower back. Normally, you would think “I have a knee problem” or “there is something wrong with my back”, but this may not be the case. The problem could be lack of range of motion at the hip joint or lack of strength of the hip muscles and your knees or lower back is paying the price for this dysfunction.

When trying to figure out the source of pain, you have to think globally.

When it comes to internal/external rotation and abduction/adduction, we don’t usually train these movements directly under load, but they are trained. Any time you change directions, cut, or twist, these movements will occur at the hip joint.

In addition, their is another hugely important movement that occurs at the hip. The acetabulum, the specific area where the femur attaches, moves upon the femur. So not only does the femur move in the acetabulum, the acetabulum moves upon the femur. This point is so highly technicala and esoteric that it is beyond the scope of this post. Yet it is hugely important. So important, in fact, that the Postural Restoration Institute has acetabular movement on the left femur as the starting point of all its therapy.

In weight training situations, confusion starts to creep in when we talk about exercises being hip dominant as opposed to knee dominant. People start to think about the small muscles that surround the hip, such as the TFL or psoas. This is not what hip dominant refers to, however.

When we talk about hip dominant exercises, we are really talking about the muscles that extend the hip. As I previously mentioned, hip extension is what occurs when you stand up from a seated position: your hips move forward. The primary extensors of the hip are the glutes and hamstrings with some contribution from the largest adductor (groin) muscle. For this reason, many exercises that strengthen the glutes and hamstrings are referred to as hip dominant and these include the squat, deadlift, lunge variations, RDL’s and good mornings.

The muscles that act on the hip joint in the front and sides are not the primary muscles involved in hip dominant exercises (although some muscles assist in more than one movement). They mostly contribute to flexion, abduction, adduction, and internal/external rotation. They have to be exercised through dynamic warmups and static stretching to maintain the ability to perform hip joint movement patterns. All hip movements contribute to overall hip mobility. Hip mobility is essential for hip joint health. Hip joint health is essential for bodily health, so they must be done. In reality, very few people consciously train movement patterns beyond hip extension and flexion, and that’s when they tend to run into trouble.

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