Normal walking and running have a certain degree of vertical oscillation, but we do not want too much

Normal walking and running have a certain degree of vertical oscillation, but we do not want too much, we want the body to move along mostly horizontal path but we do need some dampening of impact loads. We do not want to waste too much energy bouncing up and down. This is mitigated quite a bit by hip and knee flexion, the knee is well positioned to do this the easiest in many cases. Pronation and ankle dorsiflexion do dampen loads as well.

Ivo and I just recorded a class on leg length discrepancies. Here are some factors to keep in mind if there is even the smallest leg length discrepancy, anatomic or functional.

-the short leg may hyperextend at the knee , externally rotate at the hip, as well as supinate the foot (this supination is relative ankle plantarflexion, which can set up increased protective tone in calf complex and reduced strength and exposure to anterior compartment).

-the long leg side may knee flex , internally rotate at the hip, and as well as pronate at the foot (this is relative ankle Dorsiflexion)

Both of these scenarios can be going on at the same time on either leg, or it can be only on one leg. We are not perfectly symmetrical organisms, so these things can set up to help us run and walk more effortlessly, to compensate to get the head and neck properly positioned (normalizing the visual and vestibular centers on the horizon) for balance and movement through the 3 cardinal planes, and to compensate around challenging anatomy or biomechanics.

This is a complex machine, with infinite abilities to compensate and cope. But what we see is the compensation, not the problem. The joint range losses in one joint, the excesses in another, the weakness in one area, the over protection in another, the failure to tolerate loads in another, are all ways of coping and keeping us moving, . . . . . . but sometimes at a cost. . . . . pain.

shawn and ivo, the gait guys

Knee flexion in gait loading. Heeled shoes do things.

Watch this video, you have likely seen it already but did you notice it ? You will have to fast forward to 1:40 to see the video that applies to this screenshot here today.
How much knee flexion should occur during the initial loading response ? In this walking gait video, if you look closely enough, her high heeled shoes are forcing her to load in a what is technically a midfoot stride (because of the high heel) when in fact she is truly loading initially in a forefoot load, ie. plantarflexion. This abrupt load is forcing her to dampen the load with a quadriceps eccentric (if you watch closely enough, the knee flexes every time during loading, more than it should). Normally, in flat-er shoes, this knee eccentric is basically hidden (it is almost an isometric), it should never be this obvious unless one's quads are truly too weak. To be fair, the shoes are propping her into anterior pelvis tilt, as these high heeled shoes always do, which promotes lower abdominal challenges and premature quad loading, and delayed glute loading (don't believe us? stand up, dump into an anterior pelvic tilt and increased lordosis and try to engage your glutes. Nadda ! So the loading shifts into the quads).
Welcome to another ramification of high heeled shoes, again.
Admittedly, this lady does a great job. Her belt line stays pretty neutral and doesn't dip on each loading response and she is in good control. Ivo and Shawn on the other hand are terrible in their pumps :)

Sprinters, and those who forefoot load during running, are you surprised with anterior knee pain when it comes on, or achilles pain or calf tightness when the calf fatigues and can no longer hold you in adequate plantarflexion ? How about low back pain or tightness after runs ? No, you should not be surprised is the correct answer (unless you have enough durability in the quad and calf, and lower abdominals to sustain the length of your workouts, over and over and over.

Simulated knee flexion contracture to elucidate knee-spine syndrome

When we have on one side either a:
- fixed knee flexion deficit
- weak quadriceps mechanism
- short quadriceps-hip flexor complex with anterior pelvis predominance

Screen Shot 2018-01-26 at 9.16.29 PM.png

. . . these often present functionally as a short leg on that side. Perhaps better put, these will cause a premature forefoot loading response. This loading response will expedite ankle rocker during the stance phase of gait. This will often result in an overactive calf muscle complex and thus shortness over time, further blunting the ankle rocker during tibial progression over the ankle.
Furthermore, there will be a heavy lurching loading response on that same leg, it will surely look like a short leg, functionally. This is why it is imperative to check for full knee extension, ability to engage the quads with endurance and strength in full extension, and be able to connect that anterior chain with the lower abdominals and hip flexors without dumping into an anterior pelvis posture.
The loads move. They move up and down. There are many other causes of this descriptive mechanical chain problem above. Even a weak anterior shin compartment will cause many of these abrupt forefoot loading responses (that can also functionally resemble a knee flexion contracture) and promote early and excessive knee flexion during early limb loading response, when we rather should be posturing over a more stable and extended knee. They feed off of each other. It is why these syndromes of problems get intermixed and complicated to both diagnose and remedy.

PS: we chose this photo for a reason today, because high heels make us load the forefoot prematurely during the gait cycle, and we have to dampen the loads with the quadriceps.

Take what you will from this study, but it is really the global picture it suggests. That being, everything can affect everything.
PS: we hate the name they put on this study at the end. . . . "Knee-spine syndrome". For what its worth.

"However, the 30 degrees (simulated knee) contracture significantly changed the kinematics in each of the following planes. In the coronal plane, the trunk tilted to the contracture side in standing and walking. In the sagittal plane, posterior inclination of the pelvis in standing significantly increased. In addition, anterior inclination of the trunk and pelvis during walking significantly increased. In the axial plane, trunk rotation to the unaffected side significantly decreased during walking. The vertical knee force in the contracture limb decreased, being accompanied by the increase of the force in the unaffected limb during standing and walking. Results of our study suggest that knee flexion contracture significantly influences three-dimensional trunk kinematics during relaxed standing and level walking, and will lead to spinal imbalance. These facts may explain the onset of the "Knee-Spine Syndrome".

Gait Posture. 2008 Nov;28(4):687-92. doi: 10.1016/j.gaitpost.2008.05.008. Epub 2008 Jun 26.

A gait analysis of simulated knee flexion contracture to elucidate knee-spine syndrome.

Harato K1, Nagura T, Matsumoto H, Otani T, Toyama Y, Suda Y.

“Is your client feeling better because they are truly fixed, or have your prescribed corrective exercises merely raised the capacity and durability of their compensation ?  Welcome to a global industry problem.”  -Dr. Allen   Which hip will have troubles extending ?  Remember this quiz question from 2 weeks ago ? I talked about how the body will compensate to level the pelvis (and eyes and vestibular apparatus).  Lets go further down the rabbit hole.  Here is your question of the week (you may have to go back and review the prior blog post if you are unsure of how the body will cope with the slope.   Here is that first blog post.   Question: Which hip will have troubles getting into hip extension and thus terminal glute-hip-pelvis stabilization ?  Answer:  scroll down (at least think about it for a second)  .  .  .  .  .  .  Answer:  The leg on the up slope of the beach, the non-water side leg will have to be in a modest degree of knee flexion to shorten and accommodate to the slope. A Flexed knee is not an extended one and it will be far more difficult to extend the hip and get into the glutes. Propulsion will also be compromised.  For you indoor small track runners this will happen to you on the inside leg on the curves of the track. This is why we see so many hamstring injuries during indoor track.  Think about it ! It is not just bad luck.  Go ahead, tally up  your teams history of hamstring injuries, you should find more on the left leg for track runners. It is simple applied biomechanics.   Also, imagine the altered demand on the quadriceps on that flexed knee (the right knee in the picture above, and the left knee in circle track runners). Furthermore, what is the likelihood that the right pelvis will deviate into an anterior tilted posture ? You bet ya, a greater tendency, and thus a possibly shortened quadriceps/hip flexor mechanism.  Do you think this could inhibit hip extension and gluteal function ? You bet ya.  Oh, and one more thing, if you are true gait nerd, you should have asked yourself one more question, what about ankle rocker ?  Yes, you will need more ankle rocker on the beach side foot (flexed knee side). When the knee flexes, there must be more ankle rocker for this to occur, if not, you may implode into some unwelcome arch collapse, because arch collapse offers more false ankle rocker. What a mess huh !   Now, do not be shocked EVER again when your client’s come back from a sunny beach vacation from walking the beaches for hours every day, and find themselves a stark raving mad mess.  It is not the salty ocean air or the tequila, it is the slope. One could make a case that walking up and down the beach should balance things out, but that is only if we are balanced and symmetrical when we start out. Gravity always wins.  One final rant. If you are offering “corrective exercises” to your clients, you had better know at least the basics of movement and biomechanics. And further more, you had better know how to examine for them, and that means hands on assessment of the body, not just looking at how your client moves through a battery of tests. If the prior blog post  (here)  and today’s blog post principles are not remedial principles of knowledge for you, offering corrective exercises without this knowledge  and a physical exam  to confirm your assumptions is fraught with disaster, or at least helping your client to build deeper compensations on their prior compensations.   Is your client feeling better because they are truly fixed, or have your prescribed corrective exercises merely raised the capacity and durability of their compensation ?    This is the kind of stuff that keeps my new patient scheduling booked at 4-8 weeks out … . .  frustrated clients.  This is why we do not offer online consultations like some do. Because, we have not figured out how to obtain the third dimension needed in our gait and movement observation (thank you Oculus Rift, the future is near) but more so, we cannot take that information and put it together with our own physical examination to determine whether if what we are seeing is the actual problem, or a compensation. Here in lies the pot of gold.  Another clinical pearl from Dr. Allen

“Is your client feeling better because they are truly fixed, or have your prescribed corrective exercises merely raised the capacity and durability of their compensation ?  Welcome to a global industry problem.”  -Dr. Allen

Which hip will have troubles extending ?

Remember this quiz question from 2 weeks ago ? I talked about how the body will compensate to level the pelvis (and eyes and vestibular apparatus).

Lets go further down the rabbit hole.  Here is your question of the week (you may have to go back and review the prior blog post if you are unsure of how the body will cope with the slope.  Here is that first blog post.

Question: Which hip will have troubles getting into hip extension and thus terminal glute-hip-pelvis stabilization ?

Answer:  scroll down (at least think about it for a second)

.

.

.

.

.

.

Answer:

The leg on the up slope of the beach, the non-water side leg will have to be in a modest degree of knee flexion to shorten and accommodate to the slope. A Flexed knee is not an extended one and it will be far more difficult to extend the hip and get into the glutes. Propulsion will also be compromised.  For you indoor small track runners this will happen to you on the inside leg on the curves of the track. This is why we see so many hamstring injuries during indoor track.  Think about it ! It is not just bad luck.  Go ahead, tally up  your teams history of hamstring injuries, you should find more on the left leg for track runners. It is simple applied biomechanics.   Also, imagine the altered demand on the quadriceps on that flexed knee (the right knee in the picture above, and the left knee in circle track runners). Furthermore, what is the likelihood that the right pelvis will deviate into an anterior tilted posture ? You bet ya, a greater tendency, and thus a possibly shortened quadriceps/hip flexor mechanism.  Do you think this could inhibit hip extension and gluteal function ? You bet ya.  Oh, and one more thing, if you are true gait nerd, you should have asked yourself one more question, what about ankle rocker ?  Yes, you will need more ankle rocker on the beach side foot (flexed knee side). When the knee flexes, there must be more ankle rocker for this to occur, if not, you may implode into some unwelcome arch collapse, because arch collapse offers more false ankle rocker. What a mess huh !   Now, do not be shocked EVER again when your client’s come back from a sunny beach vacation from walking the beaches for hours every day, and find themselves a stark raving mad mess.  It is not the salty ocean air or the tequila, it is the slope. One could make a case that walking up and down the beach should balance things out, but that is only if we are balanced and symmetrical when we start out. Gravity always wins.

One final rant. If you are offering “corrective exercises” to your clients, you had better know at least the basics of movement and biomechanics. And further more, you had better know how to examine for them, and that means hands on assessment of the body, not just looking at how your client moves through a battery of tests. If the prior blog post (here) and today’s blog post principles are not remedial principles of knowledge for you, offering corrective exercises without this knowledge and a physical exam to confirm your assumptions is fraught with disaster, or at least helping your client to build deeper compensations on their prior compensations. Is your client feeling better because they are truly fixed, or have your prescribed corrective exercises merely raised the capacity and durability of their compensation ?  This is the kind of stuff that keeps my new patient scheduling booked at 4-8 weeks out … . .  frustrated clients.

This is why we do not offer online consultations like some do. Because, we have not figured out how to obtain the third dimension needed in our gait and movement observation (thank you Oculus Rift, the future is near) but more so, we cannot take that information and put it together with our own physical examination to determine whether if what we are seeing is the actual problem, or a compensation. Here in lies the pot of gold.

Another clinical pearl from Dr. Allen

Why can’t I squat.

Client presents to you:
On the exam table they have plenty of ankle dorsiflexion range of motion (ROM), full knee flexion ROM, full hip flexion ROM.
You then ask them to perform all 3 together in the form of a squat. The result is that they cannot even squat past parallel thighs. They have used a mere portion of the ranges which they showed plentiful on the exam table. Why ?

Possibilities: The exam showed passive movements, not active loading. Perhaps lack of Skill (unfamiliarity of the skill), lack of coordination (lack of knowing how to put the pieces together), lack of balance and body mass space awareness (ie. where do i put my parts so i do not fall over), lack of hip, knee, pelvis-core stability, etc.

“Just because you have it, doesn’t mean you own it. Nor does it necessarily mean you know how to use it or have the right to push the limits if you have never been there before.”

Ivo and i have a bunch of screens we use to glean information as we move down through the examination tree. Here is one i like to use, it is quick and easy and allows you to check something functionally and quickly while a client turns over. It is a very VERY small piece of a larger puzzle, but it is knowing what to look for and then what to test to verify. You might not have noticed this clients limitations in a passive supine joint assessment, but often when you load them up, mobility and stability challenges start to blossom into something different. If you are thinking, “possible loss of right knee flexion or left hip flexion” you are on the right track, with *caveat. There is more to it, but it is a start.  Hope to see you on www.onlinece.com next week for our new course, “thinking through functional pathologic biomechanics”.  
* Caveat: The lack of joint flexion range doesn’t necessarily mean they need more flexion, it means their flexion mobility is lost and that might mean they need more stability there or elsewhere for the flexion to present. This is the challenge a screen provides, it doesn’t tell you what’s wrong, it tells you if they can or cannot do the screen. If they cannot, it’s your job to find out why, but giving this particular client flexion work (range or strength work) would have led to a quick demise in their status. Quite often a joint displaying less mobility displays such because it has insufficient stability (from lack of skill, endurance, strength, proprioceptive etc) , but this is not a hard and firm rule. It’s your commission to find out the functional limitation(s) that are leading to these deficits and challenges.

Foot Clearance: We don't think about it until we are face down in the mud, and we have all been there.

How many times have you tripped over something so small and insignificant you can barely believe it ? We have all tripped over a small elevation in a cracked sidewalk or a curled up rug corner.  But sometimes we look back and there is no evidence of a culprit, not even a Hobbit or an elf.  How can this happen ?
Minimum foot clearance (MFC) is defined as the minimum vertical distance between the lowest point of the foot of the swing leg and the walking surface during the swing phase of the gait cycle. In other simpler words, the minimum height all parts of the foot need to clear the ground to progress through the swing phase of the limb without contacting the ground. One could justify that getting as close to this minimal amount without catching the foot is most mechanically advantageous.  But, how close to vulnerability are you willing to get ? And as you age, do you even want to enter the danger zone ? Obviously, insufficient clearance is linked to tripping and falling, which is most concerning in the elderly. 
Trips or falls from insufficient foot clearance can be related to insufficient hallux and toe(s) dorsiflexion (extension), ankle dorsiflexion, knee flexion and/or hip flexion, failure to maintain ipsilateral pelvis neutral ( anterior/posterior pelvis posture shifting), even insufficient hip hike generated by the contralateral hip abductors, namely the gluteus medius in most people’s minds. It can also be from an obvious failed concerted effort of all of the above. Note that some of these biomechanical events are sagittal and some are frontal plane.  However, do not ever forget that the swing leg is moving through the axial plane, supported in part by the abdominal wall, starting from a posteriorly obliqued pelvis at swing initiation into an anteriorly obliqued position at terminal swing. We would be remiss as well if we did not ask the reader to consider the “inverted pendulum theory” effect of controlling the dynamically moving torso over the fixed stance phase leg (yes, we could have said “core stability” but that is so flippantly used these days that many lose appreciation for really what is happening dynamically in human locomotion).  If each component is even slightly insufficient, a summation can lead to failed foot clearance.  This is why a total body examination is necessary, every time, and its why the exclusive use of video gait analysis alone will fail every time in finding the culprit(s). 
When we examine people we all tend to look for biomechanical issues unless one grasps the greater global picture of how the body must work as a whole. When one trips we first tend to look for an external source as the cause such as a turned up rug or an object, but there are plentiful internal causes as well. For example, we have this blog post on people tripping on subway stairs.  In this case, there was a change in the perceptual height of the stairs because of a subconscious, learned and engaged sensory-motor behavior of prior steps upward.  However, do not discount direct, peripheral and lower fields of view vision changes or challenges when it comes to trips and falls. Do not forget to consider vestibular components, illumination and gait speed variables as well.  Even the most subtle change in the environment (transitions from tile to carpet, transitions from treadmill to ground walking etc) can cause a trip or fall if it is subtle enough to avoid detection, especially if one is skirting the edge of MFC (minimal foot clearance) already. And, remember this, gait has components of both anticipatory and reactive adjustments, any sensory-motor adaptive changes that impair the speed, calculation and timely integration of these adjustments can change gait behaviors. Sometimes even perceived fall or trip risk in a client can easily slip them into a shorter step/stride length to encourage less single leg stance phase and more double support phase gait. This occurs often in the elderly. This can be met with a reduced minimal foot clearance by design which in itself can increase risk, especially at the moment of transition from a larger step length to a shorter one. Understanding all age-related and non-age related effects on lower limb trajectory variables as described above and only help the clinician become more competent in gait analysis of your client and in understanding the critical variables that are challenging them. 
Many studies indicate that variability and consistency in a motor pattern such as those necessary for foot clearance are huge keys for predictable patterns and injury prevention, and in this case a predictor for trips and falls.  Barrett’s study concluded that “greater MFC variability was observed in older compared to younger adults and older fallers compared to older non-fallers in the majority of studies. Greater MFC variability may contribute to increased risk of trips and associated falls in older compared to young adults and older fallers compared to older non-fallers.”
Once again we outline our mission, to enlighten everyone into the complexities of gait and how gait is all encompassing.  There are so many variables to gait, many of which will never be noted, detected or reflected on a gait analysis and a camera.  Don’t be a minimalist when it comes to evaluating your client’s gait, simply using a treadmill, a camera and some elaborate computer software are not often going to cut the mustard when it really counts.  A knowledgeable and engaged brain are arguably your best gait analysis tools.  
Remember, what you see in someone’s gait is not their problem, it is their adaptive strategy(s).  That is all you are seeing on your camera and computer screen, compensations, not the source of the problem(s).
Shawn and Ivo
the gait guys

References (some of them): 

1. Gait Posture. 2010 Oct;32(4):429-35. doi: 10.1016/j.gaitpost.2010.07.010. Epub 2010 Aug 7.

A systematic review of the effect of ageing and falls history on minimum foot clearance characteristics during level walking. Barrett RS1, Mills PM, Begg RK.

2. Gait Posture. 2007 Feb;25(2):191-8. Epub 2006 May 4. Minimum foot clearance during walking: strategies for the minimisation of trip-related falls. Begg R1, Best R, Dell’Oro L, Taylor S.

3. Clin Biomech (Bristol, Avon). 2011 Nov;26(9):962-8. doi: 10.1016/j.clinbiomech.2011.05.013. Epub 2011 Jun 29. Ageing and limb dominance effects on foot-ground clearance during treadmill and overground walking. Nagano H1, Begg RK, Sparrow WA, Taylor S.

4. Acta Bioeng Biomech. 2014;16(1):3-9. Differences in gait pattern between the elderly and the young during level walking under low illumination. Choi JS, Kang DW, Shin YH, Tack GR.