What were you thinking?

We were just talking about cognitive tasking and arm swing, and have talked about cognition altering gait. Here is a another paper on cognition (or inattention in this case) boding not so well

 

ABSTRACT: We examined factors related to conditions of life function and falls, including eye movements and gait variability, in community-dwelling older adults in Japan.

METHODS: Participants were 82 older adults (21 men, 61 women, mean age 76.1 years). We measured eye movements and gait variability during walking, and cognitive, attentional and life function. We compared two groups according to their fall history, and used a multiple logistic regression analysis to determine its relevance.

RESULTS: Fixation time, which was estimated from eye movements during obstacle crossing, and gait variability (vertical) were significantly associated with falls. There was also a significant correlation between fixation time and gait variability during obstacle crossing. In other words, the higher the gait variability in older adults, the higher the risk of falls, which was due to reduced attention estimated from eye movements during obstacle crossing that required obstacle avoidance.

CONCLUSIONS: These results show that poor attention during gait is a critical risk factor for falls in community-dwelling older adults. For fall prevention, it is necessary to promote exercises for attention, and to maintain an older adult-friendly pedestrian environment.

 

 

Inoue T, Kamijo K, Haraguchi K, Suzuki A, Noto M, Yamashita Y, Nakamura T. Risk factors for falls in terms of attention during gait in community-dwelling older adults. Geriatr Gerontol Int. 2018 Jun 27. doi: 10.1111/ggi.13462. [Epub ahead of print]

 

Projecting, calculating, the next step.

Researchers have discovered that we most accurately hit targets when we see them 1 to 1.5 steps ahead of where we were. This is more difficult that it seems because we are making a plan, and at the same time we're making that plan, we're making a movement based on the stuff that we saw a second and half in the past according to the article by Erica Pandey.


Below this link, you will find our post on projecting and estimating steps. Much along the same lines but with a great video to set it up. Here is a lead in to that article we wrote long ago, on the strange steps at a Brooklyn subway station that everyone was tripping on.

 "At Brooklyn’s 36th Street subway stop, one of the steps is slightly higher than the others. Stairs have a standardized Rise and Run and when this is altered, specifically the Rise, funny things happen. Filmmaker Dean Peterson set up his camera to capture the stumbles and the video can be seen here http://vimeo.com/44807536 and above on our blog.

The dangerous step, it turns out (which has since this video been repaired), is apparently a half-inch higher than the others. Stairway design guidelines vary within a small range.  Guidelines call for risers to be a minimum of 6 inches and a maximum of 7 ¾ inches. The allowable variance between steps is 3/8 of an inch depending on the source you seek."   Read on  . . . . . 

https://thegaitguys.tumblr.com/post/44642195883/the-funny-problem-with-the-stairs-at-brooklyns

"When walking, the brain leads the body by one step" -Erica Pandey

https://www.axios.com/we-plan-one-step-ahead-when-we-walk-scientists-say-2465394429.html

Slow Down already...

"too much tripping, soles worn thin.... too much trippin and my souls worn thin"
Scott Weiland: Stone Temple Pilots

Nothing earth shattering here. Tripping (no, not THAT kind) can be due to many variables including biomechanical as well as alterations in surfaces and/or terrain. For probable proprioceptive reasons and less brain "interpolation", walking slower decreases your trip risk. This study looked at minimal clearance of the great toe (requiring adequate ankle dorsiflexion as well as great toe dorsiflexion). This was classically used to determine trip risk. This new measure called the "trip risk integral" calculates stability throughout the gait cycle rather than just a single point in time.

The results?
 "... slower gait is both an important covariate and potential intervention for trip-related falls."

our conclusion: Look at the WHOLE gait cycle, not just at one point intime...

 

 

Schulz BW A new measure of trip risk integrating minimum foot clearance and dynamic stability across the swing phase of gait. J Biomech. 2017 Apr 11;55:107-112. doi: 10.1016/j.jbiomech.2017.02.024. Epub 2017 Feb 27.

“I keep walking into doorframes,” : A visual aspect of problematic gait you likely have not considered.   Written by Dr. Shawn Allen   Recently i had an elderly client come in to see me, we were working on some arthritic knee problems post-total knee arthroplasty. He mentioned to me that he recently had eye surgery because he was having some gait difficulties. My brain immediately when into age related gait decline, you know, balance kind of stuff.  He mentioned that he was banging into door frames because he was not clearing the sides of the door frames and was also banging up his knees, ankles, thighs and toes on many other things.  He said he had been getting anxious about his gait and thought he might be experiencing some kind of neurologic gait problem. He wasn’t trusting his gait, he feared leaving his house. He happened to mention it to his eye doctor a few months ago and here is what he told him .      “Your upper eye lids are drooping so much that they are obliterating your peripheral vision. You can’t avoid banging into things that you cannot see. Your peripheral vision is imperative for normal safe gait.”    Drooping eyelids are an inevitable effect of getting older, but the sagging eyelids can impair peripheral vision and magnify gait risks. The procedure known as a blepharoplasty is a simple procedure performed on the upper eyelid when the lid drops down and creates a lateral blind or fold blocking out the lateral eye fields. When looking to the extremes of lateral gaze or depending on peripheral vision this fold blocks the lateral field on the affected eye while the bridge of the nose blocks the same lateral field of the other eye. Effectively, the lateral gaze and peripheral vision becomes progressively narrowed.   Watch the gait of your elderly clients. Observe how they move about your office, around furniture, tables, door frames. Ask if their gait is uncertain. Ask if they are running into things for no apparent reason.  Think about this next time you are walking in close proximity of the elderly, just because you see them in your peripheral vision, does not mean they can see you.  Remember, their balance and stability is likely not what yours is, it might not take much to knock them over for what appears to be little reason at all.   From the Graci study:     “However, under CPO conditions (circumferential peripheral visual field occlusion), the doorframe led to a further   reduction in crossing velocity and increase in trail-foot horizontal distance and lead-toe clearance, which may have been because of concerns about hitting the doorframe with the head and/or upper body.”     From their conclusions, “exteroceptive cues are provided by the central visual field and are used in a feed-forward manner to plan the gait adaptations required to safely negotiate an obstacle, whereas exproprioceptive information is provided by   the peripheral visual field and used online to “fine tune” adaptive gait.   The loss of the upper and lower peripheral visual fields together had a greater effect on adaptive gait compared with the loss of the lower visual field alone, likely because of the absence of lamellar flow visual cues used to control egomotion.”    Shawn Allen, one of the gait guys.  1.  Optom Vis Sci.  2010 Jan;87(1):21-7. doi: 10.1097/OPX.0b013e3181c1d547.Utility of peripheral visual cues in planning and controlling adaptive gait. Graci V  1 ,  Elliott DB ,  Buckley JG .   2.  http://abcnews.go.com/blogs/health/2013/05/31/eye-lifts-fine-line-between-cosmetic-and-therapeutic/

“I keep walking into doorframes,” : A visual aspect of problematic gait you likely have not considered.

Written by Dr. Shawn Allen

Recently i had an elderly client come in to see me, we were working on some arthritic knee problems post-total knee arthroplasty. He mentioned to me that he recently had eye surgery because he was having some gait difficulties. My brain immediately when into age related gait decline, you know, balance kind of stuff.  He mentioned that he was banging into door frames because he was not clearing the sides of the door frames and was also banging up his knees, ankles, thighs and toes on many other things.  He said he had been getting anxious about his gait and thought he might be experiencing some kind of neurologic gait problem. He wasn’t trusting his gait, he feared leaving his house. He happened to mention it to his eye doctor a few months ago and here is what he told him .  

“Your upper eye lids are drooping so much that they are obliterating your peripheral vision. You can’t avoid banging into things that you cannot see. Your peripheral vision is imperative for normal safe gait.”

Drooping eyelids are an inevitable effect of getting older, but the sagging eyelids can impair peripheral vision and magnify gait risks. The procedure known as a blepharoplasty is a simple procedure performed on the upper eyelid when the lid drops down and creates a lateral blind or fold blocking out the lateral eye fields. When looking to the extremes of lateral gaze or depending on peripheral vision this fold blocks the lateral field on the affected eye while the bridge of the nose blocks the same lateral field of the other eye. Effectively, the lateral gaze and peripheral vision becomes progressively narrowed. 

Watch the gait of your elderly clients. Observe how they move about your office, around furniture, tables, door frames. Ask if their gait is uncertain. Ask if they are running into things for no apparent reason.  Think about this next time you are walking in close proximity of the elderly, just because you see them in your peripheral vision, does not mean they can see you.  Remember, their balance and stability is likely not what yours is, it might not take much to knock them over for what appears to be little reason at all.

From the Graci study: 

“However, under CPO conditions (circumferential peripheral visual field occlusion), the doorframe led to a further reduction in crossing velocity and increase in trail-foot horizontal distance and lead-toe clearance, which may have been because of concerns about hitting the doorframe with the head and/or upper body.”

From their conclusions, “exteroceptive cues are provided by the central visual field and are used in a feed-forward manner to plan the gait adaptations required to safely negotiate an obstacle, whereas exproprioceptive information is provided by the peripheral visual field and used online to “fine tune” adaptive gait. The loss of the upper and lower peripheral visual fields together had a greater effect on adaptive gait compared with the loss of the lower visual field alone, likely because of the absence of lamellar flow visual cues used to control egomotion.”

Shawn Allen, one of the gait guys.

1. Optom Vis Sci. 2010 Jan;87(1):21-7. doi: 10.1097/OPX.0b013e3181c1d547.Utility of peripheral visual cues in planning and controlling adaptive gait.Graci V1, Elliott DB, Buckley JG.

2. http://abcnews.go.com/blogs/health/2013/05/31/eye-lifts-fine-line-between-cosmetic-and-therapeutic/

Texting and Walking.  Your gait will change when you are texting on your phone.

You are going to want to put away your cell phone after you read this, or at least hide your parent’s phones. *(the video link attached here has likely been blocked by ABC News, you should see a forwarded link to their youtube feed. If not,

here it is

.  So you think you are a multi-tasker do you ?  Do you know how much cerebral cortex real estate is necessary to walk or drive and text ? Just try texting while walking for 5 seconds in an unfamiliar environment and see what happens.  Dual tasking is difficult especially when one task is cognitive and the other is spacial and motor. At some point something has to give, especially if you are on the edge of tapping out the executive function centers in the brain because of early disease or age related mental decline.  This has never been more prevalent than in the elderly and the number of mounting studies proving that dual attention tasks lead to a dramatic increase in age related fall injuries.  If you look into the literature the fall rate increases from anywhere from 11 to 50%, these are strong numbers correlating falls and dual attention tasking in the elderly.  Certainly the numbers are worse in the frail and gait challenged and fewer in healthier elderly folks, but the correlation seems to be strong particularly when there are even early signs of frontal cortex demise. We have talked about this on several recent podcasts

(check out podcasts 80-85)

and this has been rooted even further from one of our neurology mentors, Dr. Ted Carrick.   Recently in the Journal of Applied Biomechanics, Parr and associated took 30 young able bodied healthy individuals with experience texting on cellular phones. The study used an 11-camera optical motion capture system on a 8m obstacle-free floor. 

The study showed a reduction in gait velocity in addition to significant changes in spatial and temporal parameters, notably, step width, while the double support phase of the gait cycle increased.  Furthermore, and equally disturbing, toe clearance decreased but luckily step length and cadence decreased. 

Thus, it appears that the attention draining texting task generally forced the brain to slow the gait, reduce step length while improving stability via increasing step width and double support phase of gait, keep in mind that these are young healthy experienced individuals with no early cognitive challenges. 

This is not the case in aging adults, or in adults with factors that have either challenged gait stability (degrees of impaired balance, vision, vestibular, proprioception etc) or challenged frontal cortex function where that functionality of the brain is already nearing its tipping point for adequate function.  Sadly, these are all factors in the aging adult and they are why falls are increased and riskier for the elderly. Essentially, what the studies are showing is that dual tasking creates a distraction that can amplify any sensory-motor challenges in the system.  Mind you, there are studies that show that if the dual task is remedial such as talking while walking the effects are more muted, however in those who are at the tipping point capacity of mental executive function, mere talking (cognitive linguistic engagement), can also tip the system into deciding whether to focus on the gait or the talk but not both adequately.  Something will have to give in these folks, safe competent dual tasking is beyond the ability of their system.  As we have eluded to here, there are many factors and variables that can challenge the system. Visual challenges such as low light vision problems or depth perception challenges can act similarly on the system to dual tasking attempts and thus magnify fall risk. What about sensory challenges from a spinal stenosis or peripheral neuropathy such as in advancing diabetes?  Balance and vestibular challenges, let alone factors such as unfamiliar environments (perhaps magnified by vision challenges) as precursors are a foregone conclusion to increase fall risk in anyone let alone the elderly. By this point in this article it should be a given that texting while doing anything else is a dual tasking brain challenge that could lead to a fall, an embarrassing spill into the public pool or into a fountain at the mall let alone driving off a cliff or into a crowd of people.  But are all of these unfortunate people showing signs of frontal cortex/executive function impairment? Perhaps not, especially if they are healthy.  One has to keep in mind that texting is a high demanding cognitive attention task, even though we think nothing of it as a healthy adult. Think about it, one has to engage a separate screen other than the environment they are trying to walk through. Additionally, one has to think about what they are trying to text, engage a seperate motor program to type, then there is spelling, choosing text recipients, sending the message, watching and listening for a response, and the list goes on meanwhile the person is still trying to run the gait subprograms.  We take it for granted but texting is highly engaging and adding walking can tip the system into a challenge or failure if we are in a crowd, unfamiliar environment, low light etc.   So if you have ever wondered why elderly people trip and fall in even the most benign environments, it is likely a compounded result of challenges to situation and spatial awareness and working memory with many possible factor challenges. Again, things like poor lighting, vision limitations, unfamiliar environment, vestibular limitations, numbness in the feet, talking or even if they are simply carrying the afternoon tea to the sun room these things all are dual tasking and some require higher demands from the executive function brain centers.   Any factor(s) which tax the already-reducing executive function centers in the elderly subtract from the most basic elements required for upright posture and gait.  If dual-tasking can impair healthy young individuals, the elderly are a forgone conclusion to have magnified risks.   There can be a plus to all of this however. If the goal were to only reduce falls and fall risks in the elderly, an astute clinician can work this to their favor and do gait challenges and retraining in the office environment while safely stacking dual task challenges to expand and restore some executive function capabilities.  We are never too old to learn and lay down improved motor and cognitive patterns. So, use this information to your advantage to improve function instead of delivering it as a dark cloud to hang over your clients, whether they are elderly or neurologically challenged.  In summary, put down the darn phone, trust us, that text can wait.  Rather, enjoy the sunshine, the smiling faces, the trees.  If you are driving or walking, dump the phone and pay attention to traffic and your environment. Stop and wave to a friend. Teach your kids about this texting problem, they are likely already oblivious to many risks in the world, and this one likely hasn’t crossed their mind either. At the very least, help the elderly lady or man cross the street. By now you should understand all that they are consciously and subconsciously trying to calculate to negotiate the street crossing. Their declining executive function is often a mental feat all on its own, but having to actually add the physical act of walking (which is likely already showing aspects of age related biomechanical decline) might just be their tipping point leading to a fall.  So offer your arm, a warm smile, and think everything of it, because someday it will be you at that street corner with sweaty palms and great fear.  

Dr. Shawn Allen, one of the gait guys

References : 1. 

Eur J Neurol.

 2009 Jul;16(7):786-95. doi: 10.1111/j.1468-1331.2009.02612.x. Epub 2009 Mar 31. Stops walking when talking: a predictor of falls in older adults?

Beauchet O

1, 

Annweiler C

Dubost V

Allali G

Kressig RW

Bridenbaugh S

Berrut G

Assal F

Herrmann FR

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J Appl Biomech.

 2014 Dec;30(6):685-8. doi: 10.1123/jab.2014-0017. Epub 2014 Jul 9. Cellular Phone Texting Impairs Gait in Able-bodied Young Adults. 

Parr ND

1, 

Hass CJ

Tillman MD

. 3. 

Gait Posture.

 2014 Aug 20. pii: S0966-6362(14)00671-7. doi: 10.1016/j.gaitpost.2014.08.007. [Epub ahead of print]  Texting and walking: effects of environmental setting and task prioritization on dual task interference in healthy young adults. Plumer, Apple, Dowd, Keith. 4. 

Gait Posture.

 2012 Apr;35(4):688-90. doi: 10.1016/j.gaitpost.2011.12.005. Epub 2012 Jan 5.  Cell Phones change the way we walk.  Lamberg, Muratori 5. 

Int J Speech Lang Pathol.

 2010 Oct;12(5):455-9. doi: 10.3109/17549507.2010.486446.  Talking while walking: Cognitive loading and injurious falls in Parkinson;s disease. 

LaPointe LL

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Stierwalt JA

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The funny problem with the stairs at Brooklyn’s 36th Street subway. Why we trip..

  At Brooklyn’s 36th Street subway stop, one of the steps is slightly higher than the others. Stairs have a standardized Rise and Run and when this is altered, specifically the Rise, funny things happen. Filmmaker Dean Peterson set up his camera to capture the stumbles and the video can be seen here http://vimeo.com/44807536 and above on our blog.

The dangerous step, it turns out (which has since this video been repaired), is apparently a half-inch higher than the others. Stairway design guidelines vary within a small range.  Guidelines call for risers to be a minimum of 6 inches and a maximum of 7 ¾ inches. The allowable variance between steps is 3/8 of an inch depending on the source you seek.

(The general rule (in the US) is 7-11 (a 7 inch rise and 11 inch run). More exactly, 7 ¾ rise and an 11 ½ inch run, although some people will use a run of as little as 9 inches.)

This is a perfect example of how sensitive and predictive the human body is with all of its amazing joint position sense receptors.  But there is more to it than a simple step height differential. Read on.

There are multiple demands that stairs place on the neuro-musculoskeletal system. There are needs for input from the somatosensory, visual, and vestibular systems at various stages in the task. Some of these collaborating systems deteriorate with the aging process making the failure of stair negotiation a legitimate risk for the elderly or those that are handicapped in one of the 3 primary systems noted above. Studies (see references below) strongly link impairments in the visual system to safe stair  negotiations.  The Buckley study found that the mediolateral balance during stepping up and down stairs (single limb support stability) was significantly reduced (especially stepping down) by blurred vision highlighting the critical necessity of vision in stepping dynamics.  Hence, one must be aware of people traffic on steps, if a stairway is dense with traffic the ability to gain the visual cues of the successive stairs is paramount. The next time you are in a school or subway stairwell notice the undercurrent of your discomfort may be from the inability to see enough steps in front of you.  Letting the person ahead of you clear some distance is a must, especially if you are vision impaired, elderly, wearing dark tinted glasses or are without the ability to use other cues such as railings (ie. adding a tactile feedback system to satisfy the impairment of visual cues). 

There are other user created impairments that we may be unaware of consciously. In the Miyasike-daSilva study it was determined that as participants approached and walked stairs, gaze was within 4 steps ahead of their location indicating that individuals often rely on spatial cues from prior experience or from other visual cues to obtain the necessary information from the environment.  Thus, one must be careful carrying something such as a baby, groceries or laundry basket in front of you thus impairing the lower visual field. We have all carried something up or especially downstairs and either thought we were on the last step or found we had one more to go and found ourselves either stumbling forward or hyperextending our knee as we lurch down onto the unexpected step.  In the video you will see a great example of this forward catch as one of the ladies is carrying a baby in front of her, luckily she makes the correct saving motor choice.  Being able to plan/control landing mechanics are significantly different when the visual system is locked out or impaired from stepping tasks. Timmis found that the contribution of information from the lower visual field of gaze in controlling the landing strategy occurs predominantly prior to or during movement initiation of the foot and limb and that ‘online’ or immediate vision is used only in the latter portion of the descent phase to fine tune the step landing. Buckley found that under visual impairments subjects used the cautious strategy of keeping their weight back on the trail limb longer making weight transfer noncommittal affording the time necessary for the lead limb to fish around for the next step.

There is so much involved in negotiating stairs and steps, even level ground walking. There are many cues we have learned to subconsciously glean information from. Sadly, when we begin to age and lose proprioceptive or visual information things begin to fall apart. The system is so sensitive and intuitive. This is why when someone changes the ground level, or the height of a step as in this video, the system fails even the best of us who have all of our faculties about us. And, we learn more about gravity at that moment than we wish to learn.

Shawn and Ivo, The Gait Guys

References:

1. J Am Geriatr Soc. 2000 May;48(5):567-80. Startzell JK,Owens DA , Mulfinger LMCavanagh PR .Stair negotiation in older people: a review.

2. Gait Posture. 2005 Oct;22(2):146-53.Buckley JG,Heasley K,Scally A,Elliott DB.The effects of blurring vision on medio-lateral balance during stepping up or down to a new level in the elderly.

3. Exp Brain Res. 2009 May;195(2):219-27. Epub 2009 Mar 31.Timmis MA,Bennett SJ,Buckley JG .Visuomotor control of step descent: evidence of specialised role of the lower visual field.

4. Exp Brain Res. 2008 Jan;184(2):223-32. Epub 2007 Aug 29.Buckley JG,MacLellan MJ,Tucker MW,Scally AJ,Bennett SJ.Visual guidance of landing behaviour when stepping down to a new level.

5. Exp Brain Res.2012 Sep 22. [Epub ahead of print]Shinya M,Popescu A,Marchak C,Maraj B,Pearson K.Enhancing memory of stair height by the motor experience of stepping.

6. Exp Brain Res. 2011 Mar;209(1):73-83. Epub 2010 Dec 25.Miyasike-daSilva V,Allard F,McIlroy WE .Where do we look when we walk on stairs? Gaze behaviour on stairs, transitions, and handrails.

7. PLoS One.2012;7(9):e44722. Epub 2012 Sep 6.Does it really matter where you look when walking on stairs? Insights from a dual-task study. http://www.ncbi.nlm.nih.gov/pubmed/22970297Miyasike-Dasilva V,McIlroy WE.PMID:22970297[PubMed - in process] PMCID:PMC3435292 Free PMC Article