At the center of all sports is movement. Whether we step onto the field, rink, court, or track, movement is taken for granted. Athletes seek to improve movement whether that is their speed, their strength, or their explosiveness to achieve maximum performance. But what if the secret to maximizing performance and decreasing injury occurrence lied not with sheer movement but with another key factor? By fully understanding the mechanics of stability and its relationship with movement, and how instability causes loss of function, more effective movement can be achieved.

What are positions of stability?

Stability is created in the joints of the body by two methods: skeletal muscles crossing the joint, and the ligaments associated with the joint, whether they are intra-articular or peri-articular.  Within movement, both of these structures are crucial and when the ligaments fail to create the necessary stability (AKA instability), compensation occurs in the muscles in order to offset the instability.  This compensation mechanism can create ‘adequate’ stability in the joint for a time, but the over-activity of either the ligaments or tendons greatly increases the risk for injury.  For example, an athlete may go through most of their career with a muscular compensatory mechanism due to ligament instability, and when a greater load than expected is placed on that joint, such as a side tackle in football, the joint is not able to handle the additional stress and this can result in either a further ligamentous or musculoskeletal injury.

You may be asking then, what are the positions of stability that maximize both ligamentous and musculoskeletal stability, and how can we eliminate instability?  For the hip and shoulder, the most important joints for sports related injuries, there is a hard and fast rule- flexion and external rotation, extension and internal rotation.  The reason for this has to do with the anatomy of all the structures surrounding the joints, but most importantly the capsular structures.  Let’s take a quick look at the shoulder.  Taking a quick look at the shoulder, the fiber orientation of the capsular ligaments (Superior, Middle, and Inferior Glenohumeral Ligaments) indicates that increased tension is created in the shoulder joint when the head of the humerus is externally rotated within the glenohumeral joint.  As flexion is the primary position of the shoulder joint during movement, it is therefore arguable that maintaining some degree (slight for normal movement, maximal during high force movements), external rotation of the arm is crucial.  Taking a look at the hip we have two positions we must consider, as the hip travels through both flexion and extension during movement.  That being said, stability in the flexed and extended hip joint is maximized with external rotation and internal rotation, respectively.  This is a direct result of fiber orientation of not only the capsular ligaments, but the pubofemoral ligament (for external rotation in flexion), and the iliofemoral and ischiofemoral ligamants (for internal rotation in extension).

What are the archetypes of movement and why are they important?

Now that we described the positions of stability, we can take a look at the archetypes of both the hip and shoulder and begin to build a framework for which we can assess functional movements based on positions of stability.  The shoulder joint has 4 archetypes: the overhead press position, the hang position, the press position, and the front rack position.  Each of these archetypes can be described in terms of their anatomical orientation:

  • Overhead: flexion & external rotation
  • Hang: full internal rotation
  • Press: extension & internal rotation
  • Front rack: flexion & external rotation

Moving to the hip, we have 3 archetypes: the squat, the pistol, and the lunge, each also characterized in terms of their anatomical orientation:

  • Squat: flexion and internal rotation
  • Pistol: full dorsiflexion and hip flexion
  • Lunge: extension and internal rotation

I hope this has become clear and evident by now, but these archetypes are important because they describe functional movements in terms of positions of stability, and provide a framework for assessing movement patterns of athletes.  It is also important to note that a position of instability (a failed position) is the opposite of the archetype- for example, internal rotation of the knees in the squat is not a position of stability.  These archetypes therefore indicate areas to mobilize in order to restore proper positioning.

What happens when an athlete is missing a portion of the stable position?

When athletes are missing out on a stable position within a functional movement, there are a couple consequences that should not be overlooked.  First, the athlete has a much greater risk of injury not only in the joint of interest, but also in joints both upstream and downstream.  As the body is an amazingly interwoven and interconnected kinetic chain, changes in one joint greatly affect the positions of the joints around it.  For example, it’s not a coincidence that the creation of active external rotation in the squat places the knee is in a safer (and stronger) externally rotated position, and this results in the tibialis anterior inverting the subtalar joint, resulting in a more supinated arch arch that transmits forces more efficiently  On the flip side, when an athlete is missing external rotation in the hips during the squat, the knee internally rotates (dysfunctional movement and increased risk for pathology), and the arch drops (increased risk for pathology and decreased ability to transmit forces).  This leads to my next point- athletes lacking optimal positions of stability are dumping huge amounts of torque and are sacrificing strength and power in the process.  Forces in the body are more easily transmitted through structures which have tension associated with them (try picking up your groceries and walking a reasonable distance without creating tension in your biceps, triceps, and shoulders- much more fatiguing on the hand muscles eh?)  So my question is, why would any athlete be okay with dumping torque and limiting their athletic potential?

How should we approach addressing these issues?

Now, in order to reduce risk of injury and increase athletic performance, these issues need to be addressed.  First things first, motor control needs to be examined- can the athlete attain stable positions in dynamic situations with reduced load?  Can the athlete perform a body weight squat and create sufficient external rotation in the hips?  If yes, then this movement pattern needs to become engrained- the athlete should ‘train’ this movement pattern and not increase weight to the point where the old dysfunctional movement pattern resurfaces.  If no, then the muscles and ligaments surrounding the hips need to be mobilized.  Typically, the muscles that externally rotate the hips and also knees (sartorius, long head of biceps femoris, and all the muscles located in the glute region), and any restricted capsular ligaments need the most mobilization.

What are you waiting for?  Get into positions of stability and watch what happens to your performance.  To learn how, check out our video section.  If you’re suffering from chronic instability, book a consultation for prolotherapy by clicking here