Foot Function & Fascial Lines Series

Foot Function & Fascial Lines: Lateral Ankle Stability

In our first article of the Foot Function & Fascial Lines series we explored the integration between the Spiral Line and the Deep Front Line as it relates to propulsion and the 1st MPJ.   

In today’s article we are going to explore the functional integration between the Lateral Line and the Deep Front Line – and how understanding this integration can improve rehab and training programs for those clients or athletes with lateral ankle instability.

Importance of Topic

Ankle sprainAnkle sprains are one of the most common injuries to the foot and ankle, with a prevalence as high as 70% in sports such as basketball and soccer (Yeung 1994).

Ankle sprains can range from very minor (Grade 1) to so severe the person requires surgery (Grade 3). The most common type of ankle sprain is a Grade 1, or a minor ankle sprain with the most common mechanism of injury as plantarflexion / inversion of the ankle.

According to the American Orthopaedic Foot & Ankle Society, most patients with a minor ankle sprain never seek medical attention – however even the most minor ankle sprains demonstrate residual impairment in stability and proprioception.   In fact a 2012 study by Yentes et al. found that those athletes with a history of ankle sprains were at a 5x greater risk of re-injury with 70% of ankle sprains presenting with residual “giving way”.

Dynamic Ankle Stability – An Integrated System 

Dynamic ankle stability is achieved through both mechanical structures and neuromuscular control.   Both must be present for optimal ankle stability, with the inability of one to make up for the loss of the other.  

anklesprainimage 

Mechanical stability comes from ligaments, tendons, bony block and retinaculum (bands of fascia).   While neuromuscular stability comes from proprioceptive input from the joint capsule, ligaments, musculotendon junction, fascia and skin.

Although the above structures contribute to dynamic ankle stability on a local level, we must also consider the global control or contribution that more proximal structures have on lateral ankle stability.  

Proximal Stability for Distal Mobility 

The concept of proximal stability for distal mobility is not new to the health and fitness industry and you may currently look at your clients or athlete assessments and programming with this perspective.  

If you have not yet considered the role proximal stability plays in dynamic ankle stability, I challenge you to consider the below concept.

To begin to support this concept of proximal stability for dynamic ankle stability, a 2006 study by Friel et al. demonstrated weaker gluteus medius strength on the same side in subjects with ankle instability.  

Does this mean that the ankle sprain led to the gluteus medius weakness?  Or vice versa?

Although this may seem like a chicken or egg situation, I strongly believe that it is the latter.  

I believe that due to the deep integration between the foot and lumbopelvic hip complex, that a delay in proximal stability would set the client or athlete up for an sprain or ankle instability.

To further explain this concept we must return to Thomas Myers’ Anatomy Trains.

The Lateral Line – A Review

LateralLine

The Lateral Line begins at the base of the 1st metatarsal at the insertion point of the peroneus longus muscle. The peroneus longus travels obliquely across the plantar aspect of the foot, under the cuboid and posterior to the lateral malleolus.  

As the peroneus longus travels to the lateral aspect of the cuboid it joins the peroneus brevis muscle which attaches to the base of the 5th metatarsal.   Together the peroneus longus and brevus along the lateral aspect of the lower leg to insert at the head of the fibula.

The Lateral Line takes a jump to join the iliotibial band on the lateral aspect of the upper leg and connects to the gluteus maximus and tensor fascia lata.   Here the Lateral Line continues to join the internal / external obliques. 

The Deep Front Line – A Review

In our first article we described the Deep Front Line, but let’s review again.

In the plantar foot the Deep Front Line consists of the deep posterior leg compartment including the posterior tibialis, flexor hallucis longus and flexor digitorum longus.   For the purpose of this article we are going to focus solely on the posterior tibialis.

PTtendon

Running posterior to the medial malleolus and along the medial aspect of the foot, the Posterior Tibialis inserts onto the navicular.   After attaching to the navicular the Posterior Tibialis fans out and has 9 osseous and fascial attachments which includes:

 

–       every tarsal bone (except the talus)

–       every metatarsal (except the 1st)

–       peroneus longus tendon

–       flexor hallucis brevis muscle

This fascial attachment between the posterior tibialis and the peroneus longus joins the Deep Front Line to the Lateral Line allowing for more integrated foot biomechanics.   So in other words faster dynamic ankle stability (or Lateral Line stability) requires faster stimulation of the Deep Front Line.

Short Foot & the Deep Front Line

So how do we tap into our Deep Front Line faster?  

The answer to this question is one of my favorite exercise for foot strength – short foot!

short foot

Short foot is a foot activation exercise that was first introduced by Janda et al. This exercise targets the abductor hallucis on the medial side of the foot.  

When activated the abductor hallucis does several amazing things:

  • abducts the hallux to prepare for sagittal plane push-off
  • inverts the subtalar joint creating a locking mechanism in the foot
  • supports / lifts the navicular bone to increase the medial arch height

Because the posterior tibialis (Deep Front Line) attaches to the navicular bone, activation of short foot stimulates the Deep Front Line leading to proximal stability and subsequent Lateral Line stability.

The Evidence

A 2009 study by Nigg et al. demonstrated that the greater the intrinsic foot strength the faster the ankle stabilizers fired.   Because barefoot training is one of the greatest ways to tap into the foot intrinsics you could argue for the benefit of barefoot training in those clients and athletes with a history of ankle sprains or instability.

A 2002 study by Blackburn et al. demonstrated that after just 7 days of integrated intrinsic foot strengthening (i.e. short foot) gluteus medius activation increased by 200%!   This could further support the association between deep foot activation, proximal stability and ankle stability. 

Client & Athlete Application

So how do you apply these concepts to your clients and athletes with ankle instability?

First step is teaching them short foot!  

After the concept of short foot is understood begin to integrate short foot into all ankle stability exercises.   I particularly like barefoot balance exercises with short foot when my patients do their rehab programming.  

To see some examples of barefoot balance progressions                                                             please click HERE

To learn more about about foot function and barefoot strengthening please visit:

www.ebfafitness.com

Are you barefoot strong? 

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Barefoot Biomechanics

Toe-Spread vs. Short Foot: Intrinsic Activation

From the minimalist footwear movement to barefoot training, one of the greatest benefits of getting out of the orthotics and motion-controlled shoes is the activation of the plantar intrinsic foot muscles.

As the health and fitness industry begins to embrace the many benefits of intrinsic foot strength, researchers are starting to question which foot exercises may be the most beneficial for strengthening the plantar foot.   Which foot exercises could we consider to be evidence-based?

Abductor Hallucis Strength

If we considered the intrinsic foot musculature, the most important or most influential intrinsic muscle would have to be the abductor hallucis.

plantar intrinsics

Originating on the plantar medial aspect of the calcaneus and inserting into the base of the proximal phalynx of the great toe, this plantar intrinsic muscle:

– abducts the hallux

– creates an inversion moment to the subtalar joint

– supports or lifts the navicular bone

– stimulates the Deep Front fascial line

– drives co-activation of the deep lateral rotators

Toe-Spread Exercise 

I always talk about the short foot exercise as the most effective exercise to target this muscle, but a recent 2013 study by Kim et al. questions the benefit of short foot – and actually explores the benefit of perhaps another exercise.  The exercise in question is referred to as toe-spread.

Toe_SpreadPicture

In the study Kim et al. demonstrated through EMG analysis that when performing the toe spread exercise there was almost 45% greater muscle recruitment of the abductor hallucis.

So does this mean that toe spread trumps short foot when it comes to intrinsic muscle exercises?    Not necessarily!

Kim et al. found that the ability to perform a toe-spread exercise was limited in those subjects with a bunion due to the altered position of the abductor hallucis tendon.   It is important to note that those subjects with a bunion were able to perform short foot and achieve abductor hallucis activation.

This is important to note as many of our clients, patients and athletes may have a bunion deformity and we need to choose the most appropriate exercise to target their foot type and abductor hallucis alignment.  It should be noted that in subjects with a bunion, the abductor hallucis can still function as a subtalar joint invertor and supporter of the navicular bone.

Integrating Intrinsic Strengthening 

Whether you decide to have your clients and patients do short foot or toe spread, the programming should be the same.   I use intrinsic strengthening as the foundation to all my patient rehab and foot strengthening programs.   From plantar fasciitis to post-ankle sprain, all patients can benefit from activating the plantar foot.

Step 1 –  Activation

When activating a muscle you will want to focus on isometric contractions as these have the greatest motor unit recruitment.   Begin by hold short foot or toe spread for 10 seconds.  Relax.  Repeat 5 – 8 times.

Step 2 – Isolated Strengthening 

After waking up the abductor hallucis now you can focus on building strength and endurance in this muscle.   Perform 10 – 15 repetitions per side for 3 sets.  Your client or athlete may begin to feel the abductor hallucis fatigue or cramp.   If this happens do not push through the cramp as it can easily become a planar fasciitis-type pain.   Myofascially release the bottom of the foot before proceeding.

Step 3 – Integrated Strengthening 

Finally, because our feet and core are so deeply integrated you want to begin to integrate abductor strengthening with deep lateral rotator strength.  Throughout the repetitions focus on the deep hip and pelvic floor engagement.   To increase the activation of the deep hip and pelvic floor I encourage my clients to before their foot exercises on a single leg.

For some examples of barefoot single leg exercises incorporating short foot please click HERE

 

Are you barefoot strong?  

Reference:

Kim et al. Comparison of muscle activities of the abductor hallucis and adductor hallucis between the short foot and toe-spread out exercise in subjects with mild hallux valgus. J

Back Musc Rehab, 2013. 26: 163-168.

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Barefoot Biomechanics

Rearfoot Position and Closed-Chain Calf Stretching

Normal gait requires at least 5 degrees of ankle dorsiflexion, with maximum dorsiflexion occurring closed chain during late mid stance when the subtalar joint is passing through neutral.   Limited ankle joint dorsiflexion can result in a myriad of compensations both proximally and distally.

From knee hyperextension to midfoot over-pronation (calcaneal eversion), the deforming forces caused by tight calves is enough to make any Movement Specialist cringe.  I refer to this lack of ankle joint dorsiflexion as a “Podiatric Epidemic” as a majority of people assessed lack adequate ankle joint range of motion.

I often reference the correlation between proximal pelvic influences on ankle joint range of motion and calf flexibility.   In the case of a client or athlete with an anterior pelvic tilt position and over-active hip flexors, integrating hip flexors stretches or myofascial release will often relax the tight calves and increase ankle joint mobility.  

However for those clients or athletes who have adequate pelvic flexiblity but demonstrate decreased ankle range of motion, we want to integrated posterior group stretches.

When recommending posterior group stretches some of the classic stretches include the wall stretch, downward facing dog and dropping a heel off of the step. When performing theses stretches have you ever considered the role rearfoot position may have on the effectiveness of that stretch?  

wall stretch

A 2009 study by Jung et al. evaluated the impact of rearfoot position on the effectiveness of gastrocnemius stretching. Due to the prevalence of tight gastrocs in an over-pronated (everted) foot type, Jung et al. wanted to determine if the everted calcaneal position altered the effectiveness of the stretch.

Jung et al. evaluated 30 patients with both a neutral foot type and an over-pronated foot type with increased calcaneal eversion (average 4 degrees). Subjects performed a gastrocnemius wall stretch both in their relaxed calcaneal stance position and while wearing orthotics which placed the calcaneus in a neutral position.

Ultrasound technology was used to evaluate the degree of stretch as determined by the change in myotendinous length.   It was observed that rearfoot position had a significant impact on the effectiveness of posterior group stretching with a 3mm increase in gastroc length when the rearfoot was held in a neutral position.

Considerations for the Movement Specialist

When considering articles to review and share on the EBFA Blog, I like this study for several reasons:

  1. It emphasizes the impact subtle adjustments in body positioning can have on stretching effectiveness.   As evidence-based professionals, if we can apply research studies such as this into our client’s programming we may begin to see better results.
  1. It re-emphasizes the concept of foot-specific programming I integrate into my Barefoot Training Specialist workshops. In an over-pronated foot type with increased calcaneal eversion and decreased medial arch you want to be careful with the impact ankle stretching may have on the weakened posterior tibialis tendon.

When the calcaneus is brought out of the excessive eversion the stretch becomes more isolated to the Achilles tendon and gastrocnemius with little stress to the posterior tibialis tendon.   I have had many patients return to me after doing physical therapy and calf stretching through an everted or pronated foot.  

footblog How can the fitness professional integrate this evidence into their programming?

  1. For any clients with an over-pronated foot type, isolated gastroc stretching should be performed preferably non-weight bearing to minimize the impact of rearfoot position on the stretch.
  2. If the clients have orthotics that control rearfoot motion, perform closed chain gastroc stretches with the orthotics and then remove the shoes and orthotics for any barefoot training exercises.
  3. For any clients with an over-pronated foot type who wear Vibrams or minimal footwear for daily use and training, frequent evaluation of posterior tibial tendon condition should be performed.

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To learn more about foot-specific programming and the integration of barefoot training into your client programming please visit www.ebfafitness.com

Are you barefoot strong? 

 

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Anatomy Trains, Foot Function & Fascial Lines Series, Great Toe Mobility

Foot Function and Fascial Lines: The 1st MPJ

Fascia.   A term that just a few years ago had little meaning in the performance and fitness industry.   The days of foam rollers collecting dust in the corner have been replaced with courses specializing in fascial dissection, trigger point release and rehab programming related to fascial lines.

As we enter this paradigm shift in the way we look at human movement, corrective exercise and performance I have seen an increase in the appreciation for the foot & the ankle.   With almost every fascial line passing through the bottom of the foot, professionals worldwide can appreciate how integrated the foot and the ankle really is with the rest of the body.

In this article series we are going to take the concept of foot function and fascia further than any course or textbook on the market.  This first article is dedicated to taking a closer look at how the fascial lines influence great toe range of motion.

Let’s take the importance of fascia and foot function one step further and look at propulsion!

Propulsive Phase of Gait

Big toe

Whether we are walking, running or jumping – push-off or propulsion is characterized by dorsiflexion of our digits at the metatarsophalangeal joint (MPJ).   The joint that takes a majority of the forces during push-off and is responsible for the release of elastic energy is the 1st MPJ.

As much as dorsiflexion of the 1st MPJ may seem like a simple biomechanical movement, it is actually quite complex – requiring timed control and activation of our fascial slings.

Let’s take a closer look at the 1st MPJ.

The First Metatarsophalangeal Joint

Foot-Anatomy

The 1st MPJ is formed by the base of the proximal phalynx and the head of the 1st metatarsal.   Sitting directly under the head of the 1st metatarsal and lying within the tendons of the flexor hallucis brevis are the sesamoids.   Inserting on the medial aspect of the proximal phalynx is the abductor hallucis which is opposed laterally by the adductor hallucis.

As we begin to transition onto the forefoot and into propulsion, what dictates the range of motion of the 1st MPJ is first metatarsal position in the sagittal plane.     The image below illustrates how an elevation of the first metatarsal in the sagittal plane can block the dorsiflexion or gliding the proximal phalynx over the head of the first metatarsal.

Elevatus

So what dictates the position of the first metatarsal in the sagittal plane thereby playing a role in 1st MPJ dorsiflexion at propulsion?

If you guess the Spiral Line you are correct!

The Spiral Line – Expanded Version

In Thomas Myers’ Anatomy Trains he describes the lower part of the Spiral Line as the tibialis anterior as it joins the peroneus longus at the level of the base of the 1st metatarsal.

FeetSlingsFig1Final

Often referred by Myers at the “stirrup” of the foot, I want to expand upon this concept a little further and demonstrate how the Spiral Line plays a bigger role in propulsion than you may think!

The tibialis anterior muscle runs down the anterior aspect of the lower leg to insert on the medial aspect of the foot on the medial cuneiform (90%) and the base of the 1st metatarsal (10%).   Joining plantarly is the peroneus longus tendon which runs along the lateral aspect of the lower leg, behind the lateral malleolus and under the cuboid to insert on the base of the 1st metatarsal (90%) and medial cuneiform (10%).

With 90% of it’s insertion on the base of the 1st metatarsal, the peroneus longus plays an important role in plantarflexion of the 1st metatarsal allowing dorsiflexion of the 1st MPJ during propulsion.

So does this mean that for optimal propulsion and dorsiflexion of the 1st MPJ all we need to do is ensure proper activation of the peroneus longus muscle or the Spiral Line?

Unfortunately it isn’t that easy!   Proper activation of the Spiral Line is actually integrated with another fascial line – the Deep Frontal Line.

The Deep Front Line

For the Deep Front Line again we return to Myers Anatomy Trains.

In the plantar foot the Deep Front Line consists of the deep posterior leg compartment including the posterior tibialis, flexor hallucis longus and flexor digitorum longus.   For the purpose of this article we are going to focus soley on the posterior tibialis.

Running posterior to the medial malleolus and along the medial aspect of the foot, the Posterior Tibialis inserts onto the navicular.   After attaching to the navicular the Posterior Tibialis fans out and has 9 osseous and fascial attachments which includes:

–       every tarsal bone (except the talus)

–       every metatarsal (except the 1st)

–       peroneus longus tendon

–       flexor hallucis brevis muscle

Anatomy Foot

This fascial attachment between the posterior tibialis and the peroneus longus joins the Deep Front Line to the Spiral Line allowing for more integrated foot biomechanics.

EMG studies have shown that the posterior tibiailis activates prior to the peroneus longs during the gait cycle which means this fascial integration between the PT and PL prepares the foot for propulsion.

With the posterior tibialis as a driver of subtalar joint supination or inversion just prior to heel lift, a reflexive activation of the Spiral Line leads to stabilization of the 1st metatarsal by the peroneus longs –  allowing for dorsiflexion of the 1st MPJ and propulsion.

Client & Athlete Application

When assessing optimal propulsion in our clients and athletes remember the function of the Spiral Line and Deep Front Line on 1st MPJ dorsiflexion.   A limitation in 1st MPJ dorsiflexion or power at propulsion may be related to an impairment in posterior tibialis strength.

To optimize posterior tibialis strength in clients and athletes integrate barefoot exercises such as short foot which picks up the navicular bone and stimulates the Deep Front Line.   In addition single leg exercises can used the strength the posterior tibialis and it’s co-activation patterns with the gluteus medius and maximus.

Take a look at our webinar for related information: Optimizing Power at Push Off | High Gear vs Low Gear Position with Dr Emily Splichal

To learn more about about foot function and barefoot strengthening please visit:

www.ebfafitness.com

Are you barefoot strong? 

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