OrthoVirginia Blog

JOINT MOBILITY & STABILITY to reduce injury in various sports

By: Austin G Johns CCS CES
OrthoVirginia
Director, Post-Rehabilitation



Stability-Mobility

Sports fall upon this continuum depending upon the rigor, force, substrate, equipment, and physical application of the activity. Swimming, for instance, requires an extreme amount of shoulder mobility while boxing and rock climbing demand an excessive amount of stability at the same joint. These qualifiers, stability and mobility, refer directly to contrasting joint flexibility and strength.

Often we consider muscle strength (coupled with great neurological coordination) to be the chief determinant of high athletic prowess. The ability of an athlete to appropriately stabilize joint ranges is perhaps a better method for assessing an athlete than is pure force. Because force is uniplanar, and all sport is tri-planar, coaches and therapists are encouraged to assess their athletes in a similarly tri-planar dynamic.

Here, we'll examine which joints and joint complexes are better suited to athletics when operating in a mobile or stabile fashion as well as noting extremes in various sports.

Looking at a map of the human body, we'll define the following joint complexes:

Figure 1
 

FOOT & ANKLE

Foot and Ankle
  • Requires MOBILITY
  • Sports most commonly impacted: field & court sports
    • Soccer, lacrosse, field hockey, football, basketball, volleyball, cross country running, gymnastics

With almost every land sport, the foot and ankle complex are the most important structures to keep healthy within the mobility/stability dichotomy. Because these structures are closest to the ground, they receive the greatest impact from ground reactive force (GRF) – the force that the ground pushes back upon us whenever our foot strikes down during running or jumping.

There are 33 joints in the foot and ankle. Each one is designed to move. Motion in these joints greatly reduces GRF going up the skeletal chain. Wearing minimally restrictive equipment (shoes/taping or bracing) while training then supplementing stabilization during competition helps minimize frequently found foot and ankle restrictions.

 

HIP

Hip
  • Requires MOBILITY
  • Sports commonly impacted: baseball, hockey, football, basketball, CrossFit, soccer, lacrosse, cross country running

The hips are designed to be some of the most stabile joints in the body. Unlike the knee, they have a massive amount of support from muscles, ligaments and tendons. The hip socket is deeper than any other in the body. Even the capsule surrounding the joint is more robust than similar structures elsewhere.

Considering all this structural integrity, it stands to reason that keeping the hip mobile is advantageous. Hip stretches and strengthening are important for all athletes but some sports need much more hip mobility than others. A sprinter, for instance, should desire less hip mobility than a martial artist.

 

LUMBAR SPINE

LUMBAR SPINE
  • Requires STABILITY
  • Sports commonly impacted: golf, baseball, racquet sports, weekend warriors

The lumbar spine can be considered the scapegoat for a multitude of other physical ailments. Poor strength or flexibility at other sites including foot & ankle, hips, thoracic spine, or shoulder blade (scapula-thoracic) can easily translate as lower back or lumbar spine pain. The reason for this is the lumbar spine should have relatively little motion – only 1 to 2 degrees of rotation per segment – but they will endeavor to move excessively if there is limitation elsewhere.

In addition to good CORE strength, stability in the lumbar spine is best achieved by improving mobility and stability in other joint complexes.

 

THORACIC SPINE

THORACIC SPINE
  • Requires MOBILITY
  • Sports commonly impacted: weekend warriors, rowers, cross country runners, golf

Unlike the lumbar spine, the thoracic spine is designed to rotate, bend and flex around its segments. The range is variable from top to bottom but the "t-spine" can rotate approximately 5 to 10 angular degrees per segment. Long periods of inactivity and excessive sitting encourage these segments to stiffen.

When an athlete seeks to achieve force through rotation (think: throwing, hitting, swinging, sprinting), this limited motion is translated somewhere else – frequently in the lumbar spine, cervical spine, or the shoulder.

 

CERVICAL SPINE

Cervical Spine
  • Requires uniformly STABILIZED MOBILITY
  • Sports commonly impacted: soccer, cheerleading, football, rugby, golf

Seemingly a contradiction in terms, the cervical spine is meant to be mobile so that the head may turn when guided by the eyes or stay still while the body is moving (like walking or running). The "c-spine" needs flexibility combined with positional stability to maintain head position and balance and minimize local injury. Limitation in thoracic spine rotation, shoulder blade movement, or neck strength can instigate c-spine injury.

 

SHOULDER (gleno-humoral)

Shoulder
  • Requires STABILITY
  • Sports commonly impacted: swimming, throwing sports, racquet sports, hitting/striking sports

The shoulder joint is the most flexible in the human body. Estimates show the shoulder can achieve up to 60,000 positions! This mobility allows us to utilize our hand dexterity to its fullest. It also means that the shoulder is easily susceptible to injury when not properly supported.

Shoulder support comes from good uniform muscle structure as well as good mobility from the t-spine and shoulder blade (scapulo-thoracic) joints.

 

SHOULDER BLADE (scapulo-thoracic)

Shoulder Blade
  • Requires MOBILITY
  • Sports commonly impacted: swimming, throwing sports, racquet sports, hitting/striking sports

A "joint" too often overlooked, the joint between the rib cage and the shoulder blade is possibly the most important for shoulder health and it assists in c-spine health. The shoulder blades are meant to rise, fall, move together and separate uniformly and in tandem with the movements at the shoulder. Similar to limitations at the t-spine, when shoulder blade motion is restricted it translates somewhere else putting too much stress on adjacent joints like the shoulder and elbow.

 

ELBOW

Elbow
  • Requires STABILITY
  • Sports commonly impacted: throwing sports, racquet sports, golf, climbing, motorsports

The elbow functions similarly to the knee. However, recovering from injuries to the elbow can be a little more complicated because it doesn't have a high endurance mobile joint like the foot and ankle complex near-by for assistance. Many elbow injuries can be traced to limited upper arm and shoulder strength or limited endured strength from the hand and forearm. Elbow stability comes from appropriate modulation of surrounding musculature.

 

HAND & WRIST

Hand & Wrist
  • Requires STABILIZED MOBILITY
  • Sports commonly impacted: throwing sports, racquet sports, golf, climbing, motorsports, gymnastics

Like the foot and ankle, the hand and wrist utilize a large number of concurrent joint structures. These structures are meant to offer greater dexterity and precision to hand and finger movements. Accuracy is critical in sport but so is strength. Unlike a painter, who also requires great hand dexterity, an athlete's hand and wrist will frequently need to manipulate instruments through a forceful range. Think of a baseball pitcher throwing a curveball or a tennis player changing grips during different strokes.

In addition, there are multiple hand configurations that define grip strength. Being good at one kind of grip does not necessarily mean a person will be good at others.

Understanding joint dynamics and how forces on one joint contributes to or mitigates forces on another joint is crucial for sport therapists and coaches to help their athletes minimize injuries. While movement is not "sport specific", joint stress is and it becomes a great boon to your athletes to manage these stresses appropriately.

For more information about OrthoVirginia's Return to Sport program, contact:

Austin G Johns CCS, CES Austin.Johns@orthovirginia.com

571-599-2469

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