Heat Exertion and Gait Decline

Changes in gait characteristics are found when exertional heat stress is experienced during prolonged load carriage.  As heat stress increased, step width decreased while percent crossover steps increased. Reduced stance time variability, step width variability, and percent crossover step were observed.  These are frontal plane gait parameters for the most part. 

Think about these things during your long summer run or as you go deeper into those last miles of your long run.  Simple muscular fatigue in the frontal plane hip-pelvis stabilizers are going to render the same results.  This is quite possibly why many problems and injuries crop up in the latter miles of your run. 

Reference:

Gait Posture.

2016 Jan;43:17-23. doi: 10.1016/j.gaitpost.2015.10.010. Epub 2015 Oct 23.Using gait parameters to detect fatigue and responses to ice slurry during prolonged load carriage. Tay CSLee JKTeo YSQ Z Foo PTan PMKong PW

How well do you understand stance phase mechanics?

Here is a recent question we fielded and thought it would make a great post. 

Question/Comment: I’m slightly confused about closed chain hip motion in the stance leg.


Maybe if I explain what my thought process is you can correct me.  Lets use
left stance phase with the right leg swinging through.

After right mid-swing, the pelvis will be rotating towards the left.  The
motion of the pelvis on the left femur would be relative femur internal
rotation.  I understand that the right leg is externally rotating
(supinating) and that normal open chain kinematics of hip extension is
coupled with external rotation.  But if the pelvis is moving towards the
left AND the left femur externally rotates, wouldn’t that create too much
rotation?  So what I’m saying is that a pelvis that is oriented to the left
with a left femur that externally rotates creates an odd motion in my head
(which may be where the problem lies).  If you’ve ever seen a western where
the gun slingers do that weird walk to a shoot out…that’s what an
externally rotating femur during terminal stance looks like to me.

I’ve discussed this with other clinicians.  Some are in agreement with me,
some think it’s externally rotating, and some don’t know what I’m talking
about.  In my patients I also see a loss of hip IR more than hip ER.  These
patients that lose hip IR seem to have more difficulty in terminal
stance/toe-off phase more than the ones that lose hip ER.

If you could help me understand these kinematics and clear this up for me I
would greatly appreciate it.

Thank you, A

our reply: 

Taking your example with the L leg in stance:
When the L heel contacts the ground, the friction of the ground (hopefully) slow the calcaneus and the talus slide anteriorly on the calcaneus. 

Because of the shape of the calcaneal facets, the talus plantar flexes, adducts and everts. This sets the stage for pronation to occur: the calcaneus everts and the lower leg internally rotates, with the thigh following. The right side of the pelvis is moving to the L (counter clockwise rotation). This should occur (ideally) until midstance. At midstance, the opposite ® foot begins to enter swing phase; this should initiate supination of the stance phase leg (L). At this point, the L foot should be beginning to supinate the the leg and thigh beginning external rotation. It (thigh and leg) should reach maximal external rotation at toe off (maximal counter clockwise rotation of the pelvis) and remain in external rotation until heel strike/initial contact on the L side again. At this point, the pelvis begins clockwise rotation.

It is necessary for the thigh and leg to externally rotate while the pelvis is rotating counter clockwise, because of the constraints of the iliofemoral, pubeofemoral and ishiofemoal ligaments.

We too often see a loss of internal rotation of the hip in symptomatic populations more often than external rotation.

We hope this clarifies things for you.

Thank you again for the question and taking the time to write.

The Gait Guys

Orthotics and Foot beds, What’s the Difference?

Orthotics and footbeds, they’re the same thing, right? This is a question that is often posed to us.  No, they’re not the same, but oftentimes one or the other can be appropriate. To explain the difference, we need to understand a little bit about foot mechanics.

The foot is a biomechanical marvel.  It is composed of 26 bones and 31 articulations or joints.  The bones and joints work together in concert to propel us through the earth’s gravitational field.  It is a dynamic structure that is constantly moving and changing with its environment, whether it is in or out of footwear.  Problems with the bones or joints of the foot, or the forces that pass through them, can interfere with this symbiosis and create problems which we call diagnoses.  They can range from bunions, plantar fasciitis, shin splints, TFL syndrome, abnormal patellar tracking, and lower back pain just to name a few.

Before we go any further, we should talk a little bit about gait (ie walking pattern). Normal walking can be divided into 2 phases, stance and swing. Stance is the time that your foot is in contact with the ground. This is when problems usually occur. Swing is the time the opposite, non weight bearing foot is in the air.

 

The bones of the foot go through a series of movements while we are in stance phase called pronation and supination. Pronation is when your arch collapses slightly, to make your foot more flexible and able to absorb irregularities in the ground; this is supposed to happen right after your heel hits the ground. As your foot pronates, the leg rotates inward, which causes your knee to rotate in, which causes your thigh to rotate in, which causes you spine to flex forward. Supination is when your foot reforms the arch and makes your foot a rigid lever, to help you propel yourself; This is supposed to happen when you are pushing off with your toes to move forward. It is at this time that the entire process reverses itself, and your leg, knee, and thigh rotate outward and your spine extends backward. When these movements don’t occur, or more often, occur too much, is when problems arise. This can be due to many reasons, such as lack of movement between your foot bones (subluxation), muscle tightness, injury, inflammation, and so on.

Many people over pronate, due to incompetence of the intrinsic musculature of the lower kinetic chain, genetics, environmental factors or injuries. This means that their arch stays collapsed too long while in stance phase, and they remain pronated while trying to push off. As we discussed, during pronation the foot is a poor lever. This means you need to overwork to propel yourself forward. This can create arch pain, inflammation on the bottom of the foot (plantar fascitis), abnormal pressure on your foot bones (metatarsalgia), knee pain, hip pain and back pain.

Lets look at skiing. Skiing is a stance phase sport. While skiing, your foot stays relatively immobile in a ski or snowboard boot (i.e. it is not moving through a gait cycle). A footbed is designed to create a level surface for your feet and keep them in a neutral posture. It accomplishes this by “bringing the ground up to your foot.” They are generally custom designed to an individuals foot through many different methods. They work incredibly well (as long as the foot remains in a static posture) and many people extol the benefits and improvements in their respective sports when using these.

Orthotics are always custom made devices. They actually improve the mechanics of your foot (or give you mechanics you didn’t have before) and make it function more efficiently by altering the shape and function of the arch as the foot moves through various activities. They act like a footbed but have the added benefit of functioning while dynamic (i.e. moving) as well. This works as well or better than a footbed, and is usable in other sporting activities, such as Nordic skiing, snow shoeing, hiking, running, or biking. Many people use their orthotic in their everyday shoes, to help prevent some of the problems and symptoms they are experiencing. It should be emphasized that an orthotic IS NOT a substitution for competent musculature. We view them as an aid to assist the rehabilitation process; slowly pulling out correction as the biomechanical competence improves.  We like to call this “Orthotic Therapy”.

In summary, a footbed supports the foot in a neutral posture. It is great for activities where your foot is static or held in one position. An orthotic supports the foot in a neutral posture and improves the mechanical function of the foot. It can be used in static or dynamic activities. Remember to always consult with a professional who is well versed with the mechanics of the feet, ankles, knees, hips and back, since footbeds and orthotics have a profound effect on all these structures.

Orthotics and footbeds; they can be great assistive devices along the road to foot competence. And they can be great doorstops when you are done using them!

We are and remain..The Gait Guys.