How you load and off-load your forefoot bipod matters.

If you are a sprinter, how you load the forefoot bipod might be a variable for speed or injury. Tendons can change their cross sectional area, if you load them, but they don't change, if you don't.
Of course this article is not exclusive for sprinters, it pertains to any running sport, even endurance.
Maximum isometric force had increased by 49% and tendon CSA by 17% !
Tendons can change their cross sectional area, if you load them.
Here I show lateral forefoot loading in a heel raise, and a medial forefoot loading in heel raise. This has to be part of the discovery process outlined below. Forefoot types will play into the loading choice, and unequal strength of the medial or lateral calf compartment will also play into the loading choice made. Where do you need to put your strength ? And is the forefoot competent to take that loading challenge ? Meaning, do they have a forefoot valgus? A forefoot supinatus ? These things matter. If you are a sprinter, how you load the forefoot bipod might be a variable of foot type, asymmetrical posterior compartment strength, or foot strike pattern in the frontal plane (search our blog for cross over gait and glute medius targeting strategies for step width) ,or a combination of several or all of the above. These things matter, and why and where you put your strength matters, if you are even aware of where and how you are putting the loads, and why of course. Of course, then there are people like the recent Outside online article that says how you foot strike doesn’t matter, but it does matter. But of course, if you do not know the things we have just mentioned, it is easy to write such an article.
Isometrics are useful, they have their place. In a recent podcast we discussed the place and time to use isometrics, isotonics, eccentrics and concentrics.
One of the goals in a tendinopathy is to restore the tendon stiffness. Isometrics are a safe way to load the muscle tendon complex without engaging a movement that might have to go through a painful arc of movement. With isometrics here is neurologic overspill into the painful arc without having to actually go there.
The key seems to be load. More load seems to get most people further along. Remember, the tendon is often problematic because it is inflammed and cannot provide a stiffness across its expanse. Heavy isometric loading seems to be a huge key for most cases. But, we have to say it here, not everyone fits this mold. Some tendons, in some people, will respond better to eccentrics, and strangely enough, some cases like stretching (perhaps because this is a subset of an eccentric it seems or because there is a range of motion issue in the joint that is a subset of the problem). Now the literature suggests that stretching is foolish, but each case is unique all in its own way, and finding what works for a client is their medicine, regardless of what the literature and research says.
Finding the right load for a given tendon and a right frequency of loading and duraction of loading is also case by case specific. Part of finding the right loading position is a discovery process as well, as noted in the photos above. Finding the fascicles you want to load, and the ones you do not want to load (painful) can be a challenging discovery process for you and your client. Finding the right slice of the pie to load, and the ones not to load takes experimentation. When it is the achilles complex, finding the safe However, if one is looking for a rough template to build from, brief, often, heavy painfree loads is a good template recipe to start with.
Here, in this Geremia et al article, "ultrasound was used to determine Achilles tendon cross-sectional area (CSA), length and elongation as a function of plantar flexion torque during voluntary plantar flexion."
They discovered that, "At the end of the training program, maximum isometric force had increased by 49% and tendon CSA by 17%, but tendon length, maximal tendon elongation and maximal strain were unchanged. Hence, tendon stiffness had increased by 82%, and so had Young’s modulus, by 86%.
Effects of high loading by eccentric triceps surae training on Achilles tendon properties in humans. Jeam Marcel Geremia, Bruno Manfredini Baroni, Maarten Frank Bobbert, Rodrigo Rico Bini, Fabio Juner Lanferdini, Marco Aurélio Vaz
European Journal of Applied Physiology
August 2018, Volume 118, Issue 8, pp 1725–1736

When your calf is weak, things can dorsiflex too much sometimes.

When your calf is weak, things can dorsiflex too much sometimes. Maybe this is why you have Achilles tendinopathy. Maybe.

When we run, we either heel strike, midfoot strike, or forefoot strike. The literature is pretty clear on this now, that any one of them is not better than the other and there are many variables that need to be taken into consideration (even though many folks, who stopped reading the studies long after the barefoot craze began, will proclaim at the grave of their mother that rearfoot strike and anything but zero drop shoes are the root of all evil).

However, if you are a forefoot striker, the calf complex must be durable, strong and have enough endurance that when the foot strike occurs, that over time the complex does not allow the heel drop to become excessive or uncontrolled to the point that the achilles tendon proper exceeds its capacity to tolerate the drop, the stretch load capacity. It is more complex than this, because when the heel drops too much, too far, too fast and the arch is not durable enough, the metatarsals may dorsiflex too much and compromise the arch and stiffness of the midfoot, this can also have its complications. A weak calf can impact the rest of the foot. Remember, when the forefoot is engaged on the ground, and the heel drops in an uncontrolled fashion, we are increasing ankle dorsiflexion too, and this may not be welcomed during a stance phase of running where we are hoping for sufficient foot stiffness to load across it and propulse off of it.

This study showed that "analysis revealed that male recruits with lower plantar flexor strength and increased dorsiflexion excursion were at a greater risk of Achilles tendon overuse injury".

Intrinsic risk factors for the development of achilles tendon overuse injury: a prospective study.

Mahieu NN, et al. Am J Sports Med. 2006.

Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles.

Attached is an older video from a few years back , it is very similar in execution to the heel-rise ball squeeze exercise which is the precursor to this more functional engagement as shown in this video today.

The important premise is that you have to have command of the entire posterior compartment if you are to get safe, effective, efficient and adequate ankle plantarflexion. As we have discussed many times, if you do not have the requisite skills as shown in this video you are in trouble and ankle sprains and other functional pathologies are not unlikely to visit you. Additionally, without requisite posterior compartment endurance and an ability to engage what I like to refer to as "top end" strength in the heel rise is an asymmetrial loading issue and can lead to compensatory adaptations up the kinetic chain. Make no mistake, the load will go somewhere, and thus the work will be done somewhere. In this video you should be able to clearly see and understand that one must be able to achieve top end posturing and have command of lateral and medial forefoot loading responses and challenges if clean forward function and power is to be achieved, and injuries from extremes of motion medially and laterally are to be avoided. Furthermore, as eluded to here and in several of our podcasts (and in the study included below), an inability to achieve top end posturing will lead to changes in forefoot loading, may spill over into endurance challenges prematurely in the posterior mechanism, and create changes in the timing of the gait cycle (things like premature or delayed heel rise, premature or delayed forefoot loading, recruitment of other components of the posterior chain just to name a few). This parsing and sharing of loads and responsibilities is laid out in the Kulmala study referenced today. The study could be extrapolated to say, I believe, that particularly in sprinting, a failure to achieve top end heel rise through effective posterior mechanism contraction, will change the load sharing between the posterior compartment and the quadriceps. After all, if the calf is weak, the ankle is not in as much plantarflexion, this could mean more knee flexion and thus raise demands on the quadriceps, logically changing knee mechanics. This is exactly why we spend so much time at every patient visit looking for full range of motion at the joints and then determine the skill, endurance and strength of the associated muscles in supporting that range. Then, of course, comparing this function to the opposite limb. Symmetry is not everything, but it is definitely a major factor in safe efficient and injury free locomotion.

* Please give great thought to the part in the video where I discuss the drop phase in jumping. All too often we at looking for the propulsive mechanics and forget that a failure there will also be represented during the adaptive phase. Ankle sprains rarely occur from propulsive pushing off, they occur from a failure to properly reacquaint the foot to the ground on the following step.
-Dr. Shawn Allen, one of the gait guys.

In this study the authors noted:
"During walking, the relative effort of the ankle extensors was almost two times greater compared with the knee extensors. Changing walking to running decreased the difference in the relative effort between the extensor muscle groups, but still, the ankle extensors operated at a 25% greater level than the knee extensors. At top speed sprinting, the ankle extensors reached their maximum operating level, whereas the knee extensors still worked well below their limits, showing a 25% lower relative effort compared with the ankle extensors."

And concluded that:
"Regardless of the mode of locomotion, humans operate at a much greater relative effort at the ankle than knee extensor muscles. As a consequence, the great demand on ankle extensors may be a key biomechanical factor limiting our locomotor ability and influencing the way we locomote and adapt to accommodate compromised neuromuscular system function."

Med Sci Sports Exerc. 2016 Nov;48(11):2181-2189. Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles. Kulmala JP1, Korhonen MT, Ruggiero L, Kuitunen S, Suominen H, Heinonen A, Mikkola A, Avela J.
https://www.ncbi.nlm.nih.gov/pubmed/27327033

https://youtu.be/8T9UzOaYxmo

the gait guys
#gait, #gaitproblems, #thegaitguys, #gaitanalysis, #heelrise, #calfstrength, #toeoff, #forefootloading, #metatarsalgia, #inversionsprain

Podcast 131: Managing your injuries and body mechanics

Key Tag Words: thegaitguys, gait, gait analysis, hallux rigidus, hallux limitus, calf strength, calf endurance

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summitchiroandrehab.com   doctorallen.co     shawnallen.net

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Show Notes:

Researchers turn skin cells into motor neurons without using stem cells
https://futurism.com/researchers-turn-skin-cells-into-motor-neurons-without-using-stem-cells/

Immune cells release “red flag” to activate muscle stem cells in response to damage
http://scopeblog.stanford.edu/2017/09/25/immune-cells-release-red-flag-to-activate-muscle-stem-cells-in-response-to-damage/

Does structural leg-length discrepancy affect postural control? Preliminary study.
Eliks M, et al. BMC Musculoskelet Disord. 2017.

Evidence for Joint Moment Asymmetry in Healthy Populations during Gait. Rebecca L. Lambach  et al. Gait Posture. 2014 Sep; 40(4): 526–531.

J Phys Ther Sci. 2017 Jun; 29(6): 1001–1005.
Published online 2017 Jun 7. doi:  10.1589/jpts.29.1001
PMCID: PMC5468184

Does the weakening of intrinsic foot muscles cause the decrease of medial longitudinal arch height?
Kazunori Okamura, RPT, MS,1,* Shusaku Kanai, RPT, PhD,2 Sadaaki Oki, MD, PhD,2 Satoshi Tanaka, RPT, PhD,2 Naohisa Hirata, RPT, MS,3 Yoshiaki Sakamura, RPT, MS,4 Norikatsu Idemoto, RPT,1 Hiroki Wada, RPT,1 and Akira Otsuka, RPT, PhD5

Why some elderly take stair ascending slowly: PAD, Peripheral arterial disease.

When we think of slowing gait we think of the elderly. There is nothing new in this regard and there have been plenty of papers supporting the cognitive decline the coincides with this aging population. There is even correlation to increased fall risk, which matches up with significant  fall mortality studies.  Reduced, especially right sided, hippocampus volume and function is the current suspect in most research, and it is linked to some impairments in non-verbal memory and the slowing of gait.

Here, we see that PAD (peripheral arterial disease) can also cause a slowing of gait, particularly in stair ascent in this particular study. PAD can cause intermittent claudication pain in the calf and result in altered gait mechanics during level walking as well. The study found that those with claudication walked more slowly than healthy controls.  They also found that there was reduced vertical ground reactive forces, reduced knee extensor moment during forward continuance, reduced ankle angular velocity at peak moment and reduced ankle power generation.  They were also able to determine that the slower gait was related to the claudicated limb, that limb was the one that set the speed of gait. In other words, the system down regulated to the affected limb's capability. The study highlighted the importance of maintaining plantarflexor strength and power in those with peripheral arterial disease with effective claudication.  

Sagittal plane joint kinetics during stair ascent in patients with peripheral arterial disease and intermittent claudication.  Stephanie L. King, Natalie Vanicek, Thomas D. O’Brien
http://www.gaitposture.com/article/S0966-6362(17)30102-9/abstract?platform=hootsuite

Slower walking in the elderly and calf strength.

"Conclusions: In older men, walking at preferred speed allows triceps surae muscles to generate force with more favorable shortening velocity and to enhance use of tendinous tissue elasticity compared to walking at young men's preferred speed. The results suggest that older men may prefer slower walking speeds to compensate for decreased plantarflexor strength."

Slower Walking Speed in Older Men Improves Triceps Surae Force Generation Ability.
Stenroth, Lauri; Sipilä, Sarianna; Finni, Taija; Cronin, Neil J.

http://journals.lww.com/acsm-msse/Abstract/publishahead/Slower_Walking_Speed_in_Older_Men_Improves_Triceps.97437.aspx

More on landing mechanics.
Here is a recent article on landing mechanics. This article talks about the landing mechanics far past where I feel the first stage of vulnerability is, which is initial forefoot load, as i discuss in the video pertaining to landing from a jump or if sprinting (forefoot loading). IF landing occurs in low gear (lateral half of the forefoot), inversion risks are higher.
The medial foot tripod, high gear toe off (1st and 2nd mets) is where we should be taking off from, and landing initially upon. Anything lateral is vulnerable without the lateral column strength (lateral gastrocsoleus complex, peronei longus/brevis).
This article talks about knee flexion angles and ACL vulnerability, far after this initial loading response. The article some valid conclusions in that phase.

- Dr. Shawn Allen

Posture specific strength and landing mechanics.

http://lermagazine.com/article/posture-specific-strength-and-landing-mechanics

https://www.youtube.com/watch?v=8T9UzOaYxmo

Calf strength screen?  Um, maybe not. Specifics matter.
Thanks to barbellphysio.com for putting this up. We would like to take this deeper, because it is very important.
This screen in our strong opinion is mostly for testing sub optimal endurance, sure there is some strength assessment going on but if you are trying to determine strength, is it single rep strength ? Very likely what he truly meant is how does the calf strength hold up at a 20 rep endurance challenge.  This is more accurate and we are fussing about specifics here, but specifics matter.
*However, the potentially BIG HOLE here in the assessment, is that “perceived” top end calf/heel raise ROM is not necessarily top end FULL ROM. If one side is truly weak, and you cannot get to top end strength (say the heel is 10% lower than the other side) someone has to be there to assess and notice that top end strength failure (a top end ROM that could reduce as endurance challenge continues, but someone has to be there to observe. Going on just “feel” alone is a bad recipe there). One like is not going to feel that top end range loss even if it is large, you will perceive the effort which could feel the same as the good side but actually be a loss.  And is 20 reps enough? Sure, it is a start but is your test really telling you what you think it is telling you ? This is being shown as a gross screen in our opinion but it has holes even as a screen.  Top end strength, something we talk about here often, is critical to performance. Top end loss means  terminal plantarflexion ROM is insufficient, and this can lead to a whole host of injuries and biomechanical flaws including achilles tendonopathy to mention just one. Remember, the gastroc does  not play alone here (and gastrocs crosses the knee joint posteriorly, some of the other posterior compartment muscles do not). There is soleus, peronei, tib posterior, long flexors etc. So are you doing your test with bent knee or locked ? It makes a difference if you are trying to tease things out.  Are you ramming your toes into flexion to get more out of them to make up for a loss elsewhere ? Is the forefoot or rearfoot inverting or everting  on the up or down phase ? These things matter. Specifics matter.  For example, you can see in this video that the hip is a little lateral to the foot placement. This will mean that the heel rise will result in a lateral forefoot weight bearing load. Do you want to see if the peronei are doing their job during the heel rise ? Well then you should go into a hip hike to posture the hip over the foot so that you can get the weight bearing transition to occur terminally over to the big toe, the peronei and lateral gastroc help drive that last little shift and if they are weak and you are not driving that last piece of the movement the test may not show you the whole picture you are thinking it is. Clue, if you cannot feel the lateral compartment contract to finalize that medial foot weight bearing load shift, you may be weak there. You better assess then.

Can you do 20 reps at 80% of the full plantarflexion ROM or can you do 20 reps at 100% full plantarflexion ROM ? There is a performance difference, and to the client unobserved, the 80% on one side may feel and perform like the 100% on the other side. But make no mistake, there is a world of difference.  Someone has to  watch that you are comparing apple to apples, and not apples to figs, oranges, turnips or squash.
-Dr.Shawn Allen, the gait guys

https://www.youtube.com/watch?time_continue=55&v=QdWiXHsI8Q8