Tricks of the trade: Backward walking

image credit: https://pixabay.com/vectors/slide-sliding-falling-stickman-151861/

image credit: https://pixabay.com/vectors/slide-sliding-falling-stickman-151861/

A single event can generate asynchronous sensory cues due to variable encoding, transmission, and processing delays. Robert Peterka talks about this, along with posture compensation and system apportionment when it comes to balance and coordination of the visual, vestibular and proprioceptive systems. We have talked about that here on the blog in the past.

We are often looking for ways to “highlight” pathology and make it more visible in the clinical exam. Having your patient/client walk backwards is one of those tools.

Walking and remaining upright in the gravitational plane requires 3 integrated systems to work in concert with one another: the visual, vestibular and proprioceptive systems. Backwards walking requires a more coordinated effort AND IF there is a “hiccup” or extra demand on the system (the proprioceptive in this case), neurological processing can take a little longer, efforts can be delayed and the end result is a greater compensation is needed; this often makes pathology more evident.

Try having your client walk backwards when you are doing your exam and see what we mean. We think you will be surprised with the results : )

Dr Ivo Waerlop, one of The Gait Guys

Peterka RJStatler KDWrisley DMHorak FB. Postural compensation for unilateral vestibular loss. Front Neurol. 2011 Sep 6;2:57. doi: 10.3389/fneur.2011.00057. eCollection 2011.

temporal Shayman CSSeo JHOh YLewis RFPeterka RJHullar TE.Relationship between vestibular sensitivity and multisensory temporal integration. J Neurophysiol. 2018 Oct 1;120(4):1572-1577. doi: 10.1152/jn.00379.2018. Epub 2018 Jul 18.

Hawkins KABalasubramanian CKVistamehr AConroy CRose DKClark DJFox EJ. Assessment of backward walking unmasks mobility impairments in post-stroke community ambulators. Top Stroke Rehabil. 2019 May 12:1-7. doi: 10.1080/10749357.2019.1609182. [Epub ahead of print]

#backwardwalking #clinicalexam #thegaitguys #gaitpathology #clinicaltricksofthetrade

Balance..

Footnotes 7 - Black and Red.jpg

Did you know that the posterior spinocerebellar tract is essential for normal gait? It receives information from ALL muscle spindles, Golgi tendon organs and joint mechanoreceptors and coordinates them not only with the cerebellum but also with the vestibular system. Abnormalities within this system are present (but perhaps not apparent) all gait pathologies.

Perhaps we need to change how we are are rehabbing X (insert your favorite weight bearing joint)

image credit: https://en.wikipedia.org/wiki/StrongBoard_balance

image credit: https://en.wikipedia.org/wiki/StrongBoard_balance

We have recently run across some research that has changed the way we look at some of the rehab we do, especially proprioceptive rehab. Perhaps it will do the same for you.

Traditionally, we present increasing balance requirements to the weight bearing structure by changing one or more of the three parameters that keep us upright in the gravitational plane: vision, the proprioceptive system (which include the muscles, joints and ligaments) and the vestibular system (the utricle, saccule and semicircular canals). We have discussed them extensively in multiple articles here on the blog. We generally would make the rehab task more difficult by removing a stimulus (closing your eyes, having someone stand on foam) or challenging (standing on one leg, putting someone on a wobble board, BOSU, extending the head, etc) the to make it more durable and "educated". More difficult task + better balance = more stable joint and better outcomes. 

The importaat thing is to think about how much of each system is apportioned; we often (wrongly) assume it is pretty equally divided between the three. It turns out, that it really depends on the surface you are standing on and the circumstances.

On flat planar surfaces, the division of labor looks something like this:

  • proprioceptive system 70%
  • vestibular system 20%
  • visual system 10 %

On uneven or unstable surfaces (like a BOSU, dynadisc, foam, Swiss ball, etc), it looks like this:

  • vestibular system 70%
  • visual system 20%
  • proprioceptive system 10%

So, if we are rehabbing an ankle, it would make the most sense to do most of the rehab (and additional challenges) on a flat planar surface, perhaps incorporating things like forward, backward and side lean, toe and heel work and closed chain strengthening. WE could also close the eyes to make them more dependent on the proprio system, or extend the head 60 degrees to dampen the influence the lateral semicircular canals. We can put them on a BOSU or unstable surface but we need to remember that in that case, we will be rehabbing the vestibular system AND PERHAPS teaching THAT SYSTEM to compensate more, than the "broken" system. Yes, they get better BUT we are not fixing the system that is injured. 

You could make the argument, that your athletes/clients run/walk/exercise on uneven surfaces and use their vestibular system more.Maybe so, but is the actual injury to the vestibular system or to the musculoskeletal one?

Armed with this information, try and think of the system that is compromised and focus your efforts on that system, rather than the other two. Yes, people have vestibular dysfunction and refractive errors and need therapy, exercises and/or corrective lenses, but many of us are not vestibular or opticokinetic therapists (kudos to those of you who are!)

 

 

 

Peterka RJ, Statler KD, Wrisley DM, Horak FB. Postural Compensation for Unilateral Vestibular Loss. Frontiers in Neurology. 2011;2:57. doi:10.3389/fneur.2011.00057.

Horak FB. Postural Compensation for Vestibular Loss. Restorative neurology and neuroscience. 2010;28(1):57-68. doi:10.3233/RNN-2010-0515.

This simple screening test becomes a form of exercise.

Today we look at a simple CNS screen for your “central pattern generators” or “CPG’s”. If you do not pass, then the exercise becomes the rehab exercise. If you (or your client) does not have good coordination between the upper and lower extremity, then they will not be that efficient, physiologically or metabolically. 

The “cross crawl” or “step test” looks at upper and lower extremity coordination, rather than muscular strength. If performed for a few minutes, it becomes a test that can look at endurance as well. 

It is based on the “crossed extensor” response, we looked at last week. That is, when one lower limb flexes, the other extends; the contralateral upper limb also flexes and the ipsilateral upper limb extends. It mimics the way things should move when walking or running. 
 

  • Stand (or have your client stand) in a place where you will not run into anything.
  • Begin marching in place.
  • Observe for a few seconds. When you (or your client) are flexing the right thigh, the left arm should flex as well; then the left thigh and right arm. Are your (their) arms moving? Are they coordinated with the lower extremity?
  • What happens after a few minutes? Is motion good at 1st and then breaks down?
  • Now speed up. What happens? Is the movement smooth and coordinated? Choppy? Discoordinated?
  • now slow back down and try it with your (their) eyes closed


If  movement is smooth and coordinated, you (they) pass

If movement is choppy or discoordinated, there can be many causes, from simple (muscle not firing, injury) to complex (physical or physiological lesion in the CNS).

  • If movement is not smooth and coordinated, try doing the exercise for a few minutes a day. You can even start sitting down, if you (they) cannot perform it standing. If it improves, great; you were able to help “reprogram” the system. If not, then you (they) should seek out a qualified individual for some assistance and to get to the root of the problem.

When the going gets rough, we have a tendency to look down...

While working with a patient with runners dystonia the other day, I had one of those epiphanies. I thought I would share it with you here. Here is some food for thought. 

We remember that we have 3 systems that keep us upright in the gravitational plane: The visual system, the vestibular system and the proprioceptive system. As we age, we seem to become more dependent on the visual system, but that is a story we have told before here, and could certainly been expanded on in another post or three... 

tumblr_mvtqrj0cqk1qhko2so1_500.jpg

The long story today involves the vestibular system. It is a part of the nervous system that lives between your ears (literally) and monitors position, velocity and angular acceleration of the head. There are three hula hoop type structures called “semicircular canals” (see picture above) that monitor rotational, tilt position and angular acceleration, as well as two other structures, the utricle and saccule, which monitor tilt and linear acceleration. 

The vestibular apparatus (the canals and the utricle and saccule) feed into a part of the brain called the floccular nodular lobe of the cerebellum, which as we are sure you can imagine, have something to do with balance and coordination. This area of the cerebellum feeds back to the vestibular system (actually the vestibular nucleii, all 4 of them! superior, inferior, medial and lateral); which then feed back up to the brain (medial, inferior and superior nuclear pathway) as well as down the spinal cord (the lateral pathway) to predominantly fire the extensor muscles.

So, what do you think happens if we facilitate (or defaciltate) a neuronal pool? We alter outcomes and don’t see a clear picture. Most actions in the nervous system are a system of checks and balances, or positives and negatives, and the one the one that predominates, is the one that wins : )

Look at the picture above. Notice the lateral semicicular canals are 30 degrees to the horizontal? If you are standing up and extending your head , that lateral canal becomes vertical and the fluid inside (emdolymph) cannot flow, making it much less useful to the nervous system. Thats why it is hard to stand with your head extended and eyes closed and maintain balance (go ahead and try it, feeling is believing). Conversely, when we flex our head forward(like looking down to see what our footing looks like), we move this lateral canal onto a more physiologically advantageous position, enhancingour balance.  If you are on uneven ground, have an injury or are having issues with proprioception (like many folks do), this actually helps the vestibular system (as well as the proprioceptive and visual systems) to work more efficiently. 

OK, have that? Now one more concept..

So if we look down, we put a slow stretch into our neck extensor muscles, which just happen to have some great postural receptors in them, called muscle spindles, along with mechanoreceptors in the capsules of the joints. So, facilitating (ie. exciting) these receptors, fires more information into our cerebellum, the queen of balance in the nervous system. What do you think happens? Even better balance and coordination! The 2 systems work together, summate to improve movement and balance!

Wow. All this from head position…The key here is to realize what and why you are doing what you are doing....

On the topic of endurance training.....

On the topic of endurance training (which we discussed on this weeks PODcast, forthcoming in the next day or so; we have both been extraordinarily busy in our clinics); if you are a well trained athlete (ie endurance junkie), how might this effect your running gait?

So, you run 103 miles with an elevation change of over 31,000 feet, how do you think you would fare? These folks were tested pre and 3 hours post race on a 22 foot long pressure walkway at about 7.5 miles per hour. Here’s how this group of 18 folks did:

  1. increased step frequency
  2. decreased “aerial” time
  3. no change in contact time
  4. decrease in downward displacement of the center of mass
  5. decrease in peak vertical ground reactive force
  6. increased vertical oscillation
  7. leg stiffness remained unchanged

So what does this tell us?

  • wow, that is a lot of vertical
  • holy smokes, that is really far
  • don’t know how I would do with a race like that
  • they are fatigued (1, 2, 6)
  • they are trying to attenuate impact forces (2, 3, 4, 5, 7)

The system is trying to adapt the best it can. If you were to do a standard hip screen test (like we spoke about here)  you would probably see increased horizontal drift due to proprioceptive fatigue. Remember that proprioception (our bodies ability to sense its position in space) makes the world go round. Proprioception is dependent on an intact visual system (see our post yesterday) , an intact vestibular system and muscle and joint mechanoreceptors functioning appropriately). We would add here that central nervous system fatigue (ie central processing both at the cord and in the cortex) would probably play a role as well.

The take home message? The human machine is a neuro mechanical marvel and much more complex than having the right shoe or the right running technique. Training often makes us more competent and efficient, but everything has it limits.

The Gait Guys. Making it real with each and every post.

all material copyright 2013 The Gait Guys/ The Homunculus Group

J Biomech. 2011 Apr 7;44(6):1104-7. doi: 10.1016/j.jbiomech.2011.01.028. Epub 2011 Feb 20.

Changes in running mechanics and spring-mass behavior induced by a mountain ultra-marathon race.

Source

Université de Lyon, F-42023 Saint-Etienne, France. jean.benoit.morin@univ-st-etienne.fr

Abstract

Changes in running mechanics and spring-mass behavior due to fatigue induced by a mountain ultra-marathon race (MUM, 166km, total positive and negative elevation of 9500m) were studied in 18 ultra-marathon runners. Mechanical measurements were undertaken pre- and 3h post-MUM at 12km h(-1) on a 7m long pressure walkway: contact (t©), aerial (t(a)) times, step frequency (f), and running velocity (v) were sampled and averaged over 5-8 steps. From these variables, spring-mass parameters of peak vertical ground reaction force (F(max)), vertical downward displacement of the center of mass (Δz), leg length change (ΔL), vertical (k(vert)) and leg (k(leg)) stiffness were computed. After the MUM, there was a significant increase in f (5.9±5.5%; P<0.001) associated with reduced t(a) (-18.5±17.4%; P<0.001) with no change in t©, and a significant decrease in both Δz and F(max) (-11.6±10.5 and -6.3±7.3%, respectively; P<0.001). k(vert) increased by 5.6±11.7% (P=0.053), and k(leg) remained unchanged. These results show that 3h post-MUM, subjects ran with a reduced vertical oscillation of their spring-mass system. This is consistent with (i) previous studies concerning muscular structure/function impairment in running and (ii) the hypothesis that these changes in the running pattern could be associated with lower overall impact (especially during the braking phase) supported by the locomotor system at each step, potentially leading to reduced pain during running.

Copyright © 2011 Elsevier Ltd. All rights reserved.

http://www.ncbi.nlm.nih.gov/pubmed/21342691