It's All In The Hips: The 4-Layer Hip Mobility Framework for Hockey Players

“It's all in the hips” as the legendary Chubbs Peterson from Happy Gilmore said in 1996.

All of us who work in the hockey community fancy ourselves experts of the hip, not necessarily by choice. We need to understand the hip because it is our players' lifeblood, their engine, and sometimes their demise.

I am writing this editorial to describe a “mobility” framework that we have used successfully with our athletes. Is this framework perfect? No, but it is a systematic way to approach evaluating and maximizing hip range motion.

Approaching the hip can seem daunting for a bunch of reasons.

First, the hip is a synovial ball and socket joint that allows significant motion in all three planes. With all this motion it is important to understand what exactly contributes to the overall movement of the hip. Simplifying and breaking down the hip into different layers can make programming exercises pragmatic and specific; this is the “Layer Concept.”

The 4 Layers of The Hip

Draovitch et al. 2012 outlines 4 layers at the hip:

• Layer 1 the Osseous
• Layer 2 the Inert
• Layer 3 Muscular
• Layer 4 Neuromechanical.

While the original purpose of this approach was to evaluate the painful hip, it can be a useful way to organize our mobility programs. First, let's differentiate between mobility and flexibility. This creates a hot stove when defining these two terms, but this how I define them:

Flexibility = The ability of a muscle or muscles to lengthen passively through a range of motion; “static” “singular motion

Mobility = The ability of a joint to move through desired a range of motion; could be active or passive

Vilify me for my definitions, but mobility is how a joint(S) moves overall which is influenced by multiple structures.

Mobility can then be active or passive; passive mobility is a provider doing a range of motion exams on a table.

Active mobility is the ability of the athlete to control the joint through a range of motion. Flexibility is a singular look at a muscle(s) ability to lengthen. Flexibility is a component of hip mobility. To the best of my ability, I want to optimize the flexibility, passive mobility and active mobility of the athlete prior to on or off ice workouts.

Working with the hockey player, we understand the importance of mobility/range of motion for the hip, as deficits can be risk factors for pathologies such as Femoroacetabular Impingement, Adductor Tendinopathy, Core Muscle Injury and other pathologies around the pelvis.

The Osseous Layer

Getting back to the layer approach for hip mobility let's start with the Osseous Layer. This is the underlying bony architecture of the hip joint. There are many parameters to consider in this domain, and most of them require medical imaging (X-rays, CT, and MRIs).

The majority of our players have had hip imaging somewhere along the path and we have included it as part of the PPME. I argue a simple plain radiograph is prophylactic for the hockey player and should be part of the PPME. I would highly recommend basic X-rays for your newly drafted athletes or athletes new to your organization.

Reviewing an X-Ray with your Team Physician can help you identify “at risk” hip athletes. Then you can work with these athletes and educate them on the importance of mobility and discuss what they should avoid.

The imaging reports help us understand any bony findings that make us need to avoid certain mobility positions. On the imaging reports, you can identify large CAM lesions of the Femur, Acetabular Protrusio (Large Sockets), Acetabular Retroversion, enlarged Sub Supine or femoral retroversion.

For example, a recent 3-D CT study looked at the degree of bony impingement on patients with increased femoral retroversion and found that increased retroversion lead to increased Sub-Spine (54%) and Anterior impingement with hip flexion (89%) compared to patients with normal version, 29% and 64% respectively. This would suggest an athlete with excessive femoral retroversion may need to avoid mobility exercises that place them in high degrees of hip flexion, such as 90-90 PAILS/RAILS that are commonly prescribed.

I find that the osseous layer helps determine what mobility exercises the athlete should AVOID and what mobility goals are realistic.

As another example, an athlete who has a large CAM lesion (>65 degrees) may not be able to increase their internal rotation range of motion due to the constraints of the bony anatomy. Instead, our goal for this athlete may be to maintain the internal rotation range of motion as they go through the season. A great study of hip radiographs was conducted by Larsen et al 2017 which showed that between 85-89% of hockey players within an organization have CAM morphology of the femur. 64% of the athletes had a posterior wall sign which is a measure of acetabular retroversion (pincer lesion).

These findings suggest we need to be cautious with a huge number of our players to avoid repetitive hitting of the femoral head against the acetabulum by trying to increase motion that doesn't exist. The osseous layer also helps us to set realistic goals for our mobility program.

Here are three specific mobility exercises that address the osseous layer, adapted from Reiman et al 2013. They are all self-mobilization techniques that try to use the arthrokinematics of the hip to increase motion. We utilize the natural movements of the femur on the acetabulum, or vice versa, to our advantage. As staff, we try to improve inferior glide of the femur during hip flexion, a posterior glide during rotation of femur, and posterior inferior glide during hip adduction in an extended position.

The Inert Layer

The next layer we want to address is the inert layer, which provides passive stability to the joint. This layer includes the capsule, the labrum, ligamentum teres, and ligament complex. When thinking of mobility training, the one specific structure in this layer that directly impacts mobility is the joint capsule.

The Capsule is defined as a fibrous structure surrounding the hip joint comprising three external ligaments directed longitudinally and circumferentially. A study by Zhang et al. 2017 looked at the role of capsular thickness and its relationship to hip range of motion in those with FAI. They found that capsular thickness was negatively correlated with hip flexion and IR range of motion; p=.0042 and .023 respectively.

This suggests that our players who have a significant CAM lesion, 89% of them, may benefit from mobility-based exercises targeting this thick capsule. While this is correlative research, I have seen capsular based stretching to be effective at improving hip flexion ROM in our players. Two specific exercises we use with our players are a targeted anterior hip capsule stretch with a band and a posterior capsule stretch in a quadruped position (active and dynamic).

We need to use caution when prescribing the posterior capsule stretch shown below because this position might not be attainable for our athletes with increased acetabular coverage of the femur, femoral retroversion, or other osteological reasons.

There are some Postural Restoration Institute posterior Capsule stretches that might better suit the athletes with pain in position shown below. Additionally, I understand that to create true capsular deformation you must use the principle of creep. Creep and true capsular deformation is beyond our scope here, but addressing the capsular component of the hip can result in improved motion through neuro-physiological mechanisms. One other note on the inert layer, a small number of athletes don't have the classical hockey hip (FAI). There are dysplastic (4%) and borderline dysplastic players (24%). Stretching their capsule may be detrimental. These are our hypermobile athletes. This is another reason to do prophylactic X-Rays to identify these athletes and avoid doing harm. A hypermobile athlete relies more on the static stability the capsule provides because they don't have the built-in bony stability.

The Muscular/Contractile Layer

The muscular/contractile layer encompasses any muscle that crosses the hip and pelvis. This would be where we can address flexibility and identify any specific muscle groups that are “tight.”

We could have another hot stove debate here about why a muscle is “tight.” It could be caused by a number of factors, from true muscle shortening, to overactivity of a muscle, to a weak muscle, and more. The bottom line of all the reasons is that we need to address decreasing mobility in our mobility program.

The muscle groups that limit range of motion/mobility are the Adductors, Iliopsoas, Rectus Femoris, Hamstrings and Lumbar Extensors.

Previous literature has shown the benefit of dynamic stretching or static prior to activity, thus we implement more dynamic exercises. Additionally, due to time constraints we often combine thoracic rotation or extension movements to optimize time. Furthermore, adding in these thoracic/upper extremity movements fits in with the Anatomy Trains Fascial Sling Paradigm (a topic for another day).

(Check out this article for more on Nordic Curls.)

The Neuromechanical Layer

The final layer is neuromechanical. Locally this layer refers to the neurovascular structures, mechanoreceptors, and nociceptors. On a global scale this is how the athlete moves. We get to see how their acetabulum moves on the femur with activity.

These would be exercises that aim to improve movement quality, biomechanics of specific motor program, kinetic sequencing, or however you prefer to address motor control. Here we are trying to use the mobility created with our previous exercises to improve a motor program. Exercises from this layer try to influence the pelvis on femoral biomechanics. Changes within pelvic control could lead to an increased anterior tilt of the pelvis leading to restricted hip flexion and internal rotation, as one example.

One study, by Kobayashi et al. 2021 showed that decreasing anterior pelvic tilt by 10 degrees was equivalent to performing an arthroscopic CAM resection in terms of increasing a patient's internal rotation range of motion. Further, decreased anterior pelvic tilt by 10-degree lead to a 6.5-degree internal rotation gain at 90 degrees of hip flexion. 10 degrees of anterior tilt caused more anterior/front sided osseous impingement.

I am not here to advocate for PRI, DNS, FRC, or any other paradigm over the other. I advocate for using exercises to help restore optimal relationships between the pelvis and femur that our athletes can complete. Here are some of the techniques I've used with my athletes.

Other Considerations for Your Hip Mobility Program

When we program our mobility routines we take the following into consideration: time constraints, time of year, goal of the current training phase, and compliance to the program.

Mobility is just one physiological bucket we need to address, and I want to make sure that the athlete is getting the effective dose without compromising other buckets. We try to choose one to two exercises from each layer, maybe three if we have a regeneration/low stim day. Ideally the hip mobility routine would take ~5-7min to allow the player enough time to complete mobility of foot/ankle, mobility of thoracic spine, activation of muscle groups, increase core body temperature and other areas of a proper warmup.

Here, my goal is to present a framework for prescription hip mobility exercises. The goal is not to be an exhaustive list of exercises that you can prescribe, or give you the perfect mobility program for your athletes. There is room for creativity and pragmatism, but the approach makes sure that we are evidence based.

Please reconsider wildly giving out mobility exercises that are all the craze on social media or beating guys up with variations of 90/90 mobility exercises.

We need to recognize that certain athletes can't do some of these mobility challenges and they might increase bony impingement leading to increased pathology and joint morbidity. I know I have probably offended someone in writing this article to whom I apologize. Feel free to tell me where I was wrong. That said, in my experience this approach has served our athletes well and I hope it can help you.

Thanks for reading,

Nick Andreas PT, DPT, SCS, CSCS

Physical Therapist/Assistant Strength and Conditioning Coach for the Dallas Stars Hockey Club

References

Draovitch P, Edelstein J, Kelly BT. The layer concept: utilization in determining the pain generators, pathology and how structure determines treatment. Curr Rev Musculoskelet Med. 2012 Mar;5(1):1-8.

Kobayashi N, Higashihira S, Kitayama H, Kamono E, Yukizawa Y, Oishi T, Takagawa S, Honda H, Choe H, Inaba Y. Effect of Decreasing the Anterior Pelvic Tilt on Range of Motion in Femoroacetabular Impingement: A Computer-Simulation Study. Orthop J Sports Med. 2021 Apr 20;9(4):2325967121999464.

Larson CM, Fuller D, Ross JR, Rowley D, Giveans MR, Stone RM, Bedi A. Characterizing Radiographic Hip Anatomy and Relationship to Hip Range of Motion and Symptoms in National Hockey League (NHL) Players. Orthop J Sports Med. 2016 Mar 24;4

Lerch TD, Antioco T, Boschung A, et al. Hip Impingement Location in Maximal Hip Flexion in Patients With Femoroacetabular Impingement With and Without Femoral Retroversion. The American Journal of Sports Medicine. 2022;50(11):2989-2997

Reiman MP, Matheson JW. Restricted hip mobility: clinical suggestions for self-mobilization and muscle re-education. Int J Sports Phys Ther. 2013 Oct;8(5):729-40.

Zhang, K., de SA, D., Yu, H. et al. Hip capsular thickness correlates with range of motion limitations in femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc 26, 3178–3187 (2018).