Gait Keeping!

Webster’s defines a gatekeeper as “one who controls access.”  And in a sense, this is what our gait does.  Regardless of whether we are running or walking it determines how we move through our day. 

Several things come to mind when looking at gait:

  1. To walk or run we engage the entirety of our lower kinetic chain, from the hips to our tippy-toes.
  2. The muscles, ligaments, tendons, and joints in that chain are intricately designed to do certain things and if those elements are not functioning properly, our gait is compromised.
  3. Gait deteriorates with age.  However, vigilance can allow us to forestall many common effects and even partially reverse some of what may have taken hold. 

First, let’s underscore the importance of gait.  Aside from our ability to think, being mobile is arguably the most joyful thing we do.  It’s a rare person who has not been laid up for a time.  We go stir crazy!  And can’t wait to get moving again!!  Sometimes to our peril we come back too fast and hard.  But that’s a topic for another post.

Now let’s look at gait anatomy.  Starting at the hip, which is not a separate structure, rather a ball-and-socket joint formed by the articulation of the acetabulum (a concave indention in the pelvis) and the round head of the femur (our thigh bone.)   Aside from the shoulder, this joint has the body’s greatest range of motion.  Its stability is enhanced by cartilage, ligaments, and labra with movement controlled by 22 distinct muscles pulling in various directions against the articulating bones.  If any of these muscles are too strong, weak, or inflexible, it affects our gait.

The femur, which resides between the hip and the knee functions as a long lever.  It is the largest bone in our body and comprises about one-quarter of our height.  When running, the femur normally moves (flexes and extends) at the hip joint about 105°.  The four quadriceps in the front of our leg and the three hamstrings in the back are key drivers of leg motion.  If the quads are considerably stronger than the hamstrings, often the case with runners and cyclists, this can lead to a pulled hamstring, which every runner knows is debilitating!

Heading south, we arrive at the complex knee joint.  The anatomy books show the end of the femur fitting neatly onto the upper notches of the tibia (our lower leg) to form the tibiofemoral (knee) joint.  It’s not always such a perfect fit and small changes in angles at this joint can lead to all sorts of problems.  As a synovial hinge joint it resides in an enclosed capsule and functions largely in one plane.  This allows for knee flexion and extension, critical movements when we run or walk.  In the front is our kneecap, the patella. The most common injury in runners is knee pain at the patellofemoral joint, which among other things can be triggered by a knee collapsing inward upon impact.

Below the knee, the tibia provides the majority of the support down to the foot, with the parallel fibula largely functioning as an insertion point for various muscles.  Our biomechanics place a lot of force on the tibia, and that is where many stress fractures are observed.

We finally arrive at the foot/ankle, thinking there is already enough to worry about above it!   But each foot has 26 distinct bones, 20 articulating joints, and over 100 muscles, tendons, and ligaments.  Any of these malfunctioning can cause a problem!  To boot, there is probably more variation in foot motion among athletes than any other part of the body.  So a lot to keep track of! 

With basic lower extremity anatomy covered, the last part of this post hones in on what we can do to be gait keepers.  Ferber & MacDonald (Running Mechanics and Gait Analysis, 2014, Human Kinetics) note there are four factors to consider in gait assessment:

  1. Anatomical alignment
  2. Biomechanical gait patterns
  3. Muscular strength
  4. Tissue flexibility (and range of motion)

I would add a fifth factor – a commitment to continually address at least the last two items, over which we have the most control.  While exercise science explains how the lower extremity kinetic chain functions, we know less about what exercise programs most effectively address gait deficiencies.  Fortunately, technology is on our side.  Nic Fiorentino and Ryan McGinnis, professors in biomedical engineering at UVM, are developing wearable technology to measure various parameters of gait.  This would extend gait measurement beyond the lab, where reflective sensors are used to detect movement, to anywhere, anytime monitoring.  Just as activity trackers have revolutionized the monitoring of physical activity, such technology would provide vital feedback on gait for both researchers and individuals, whether or not they are participating in studies.

Regarding strength, the key to propulsive foot movement is activated plantarflexors. These include our calf muscles (gastrocnemius and soleus) and three deep muscles in the back of our leg (tibialis posterior, flexor hallucis (big toe) longus, flexor digitorum (smaller toes) longus.  These muscles propel us forward.  When we go “up on our toes” it is the plantarflexors that get us there.  When these muscles are weak, we lose “pop” in our step.  Biomechanically, the other side of story is our foot extensors.  They too have long names but in short enable us to lift up (dorsiflex) the front of our foot as we begin the gait cycle.  If the extensors are weak we slide into the step and shuffle along.  We often see this in older runners and non-runners alike.  An invitation to trip and fall! 

Running speed is a function of stride length and rate (cadence) and is linked to gait.   If our muscles or joints are stiff, range of motion is hampered.  Thus, even if cadence remains intact we slow down.  Impaired range of motion decreases “flight time” — when both feet are airborne.   Studies confirm a decrease in flight time negatively impacts speed.  Additionally, a decline in average stride height not only affects speed but also leads to more tripping and falling.  This is where a corollary to walking comes in: regardless of speed, if we are not sufficiently lifting our feet, we tend to stub our toes and trip.   

As to exercises, calf raises (first with body weight and then weighted), marching with high leg lift, and simple jumping and skipping will send the right message to these muscles.  One can then progress to long jumps (OK, maybe short jumps to start!) and low box jumps as well as progressive skipping and jumping drills.  Following up these exercises with several sets of 30-second static stretches will enhance hamstring range of motion and can be done with ropes or bands

Gait is a big topic and I’ve barely scratched the surface.   Subsequent posts will dig deeper into ways to enhance it.  Bottom line, gait is vital to us regardless of age.  But perhaps more so as we age.   Let’s be gait keepers!

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