Whole-body coordination patterns may become partitioned in particular ways as a function of task requirements

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Toddlers actively reorganize their whole body coordination to maintain walking stability while carrying an object. Hsu WH1, Miranda DL2, Chistolini TL3, Goldfield EC4. Gait Posture. 2016 Oct;50:75-81


Today we seem to be going back to dual-tasking again, in this case utilizing the arms as balance assistance devices, amongst their other functions. However, we all know that walking with a hand in a pocket, or carrying something alters our ability to maximize their ballast-like function. Balanced walking involves freely swinging the limbs in pendullar motion. Changes in arm swing will change gait economy and efficiency. We have all run with a water bottle or bag/briefcase and know how that changes the symmetry and fluidity of our gait.

"Whole-body coordination patterns may become partitioned in particular ways as a function of task requirements.”

Today's research piece discusses toddlers and their function as they carry objects.
"children immediately begin to carry objects as soon as they can walk. One possibility for this early skill development is that whole body coordination during walking may be re-organized into loosely coupled collections of body parts, allowing children to use their arms to perform one function, while the legs perform another. Therefore, this study examines: 1) how carrying an object affects the coordination of the arms and legs during walking, and 2) if carrying an object influences stride length and width." -Hsu et al.
In this study of 10 toddlers with 3-12 months of walking experience were recruited to walk barefoot while carrying or not carrying a small toy.

"Stride length, width, speed, and continuous relative phase (CRP) of the hips and of the shoulders were compared between carrying conditions. While both arms and legs demonstrated destabilization and stabilization throughout the gait cycle, the arms showed a reduction in intra-subject coordination variability in response to carrying an object. Carrying an object may modify the function of the arms from swinging for balance to maintaining hold of an object. The observed period-dependent changes of the inter-limb coordination of the hips and of the shoulders also support this interpretation. Overall, these findings support the view that whole-body coordination patterns may become partitioned in particular ways as a function of task requirements." -Hsu et al.

So once again we will say it, if you are coaching the arm swing YOU want, because you do not like what you see in your client, or if you think you are helping your client get more out of their body in terms of speed, power, efficiency or anything of the sort, know that there is a higher, smarter program running the show. And that program in the client’s CNS is smarter than you when it comes to what they need for whole-body coordination pattern generation.

photo credit: courtesy of Pixabay

The Pelvis and COM in locomotion.

"Biomechanics of unobstructed locomotion consists of synchronized complex movements of the pelvis, torso, and lower limbs. These movement patterns become more complex as individuals encounter obstacles or negotiate uneven terrain."

This data was taken on 10 healthy young adult individuals investigation specifically the mechanics of the pelvis, torso, and lower limb segments and how they relate to obstacle negotiation of varying sized objects combined with temporal constraints to perform the task.

The data "revealed a significant increase in sagittal (posterior tilt) and frontal (ipsilateral hike) plane pelvic angular displacement and higher sagittal plane posterior torso lean angular displacement with increased obstacle height. Furthermore, both sagittal plane hip and knee maximum joint flexion were significantly higher with increasing heights of the obstacles during negotiation."

https://www.ncbi.nlm.nih.gov/pubmed/28297177

Imagining can make things better.

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Visualization is a key in most sports and activities if one wants to improve their skill and performance.  Gait retraining through visualization should thus work as well. This study which has yet to be executed, hypothesizes that we should be able to change and improve our gait through visualization of changes.  Motor imagery, envisioning motor actions without actual execution, has been used to improve gait in Parkinson's disease and poststroke. In this study subjects will be asked to specifically imagine walking, imagine talking and imagine walking while talking.  It will be interesting to see what they discover, but we suspect that this should be like improving any other motor task, that visualization improves the task.  Learning occurs on several levels.  One should also consider not only asking clients to do their prescribed corrective exercise homework and movements, but also visualize them even when actual physical execution is not feasible.

Neurodegener Dis Manag. 2017 Nov 22. doi: 10.2217/nmt-2017-0024. [Epub ahead of print]
Motor imagery of walking and walking while talking: a pilot randomized-controlled trial protocol for older adults. Blumen HM1, Verghese J1.

Dual tasking, Pokemon, and Cross walks.

Someone has to save the Pokemon Go users. The Gait Guys to the rescue !
With the help of these pavement tiles by design firm Büro North, they created a street tile that alerts phone users when they’re approaching danger. Smart Tactile Paving, a concept that would alert walkers — much like a street light — when they’re nearing traffic with the standard red, yellow, green system (see the article link below for this product and idea).
Someone has figured out how to stop you from texting into the street at a cross walk while you and your kids scoop up Squirtles and other nonsense. Oy Vey. 
You are looking down while on your smart phone and some inventor knew they had to do something to save the world from the Pokemon Go death mark population control device. 
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.
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.

There is much more to say about this today on the blog. It is Rewind Friday, come get reacquainted with the problems your kids will have playing pokemon go.
-Shawn

https://thegaitguys.tumblr.com/post/104851280879/texting-and-walking-your-gait-will-change-when

http://thenextweb.com/insider/2016/07/28/these-pavement-tiles-could-stop-phone-addicts-from-walking-into-traffic/

 

Gait and the lower visual field.

Gait and the eyes. We forget about the eyes. If you have vision issues, your gait may change.
Gaze during adaptive gait involving obstacle crossing is typically directed two or more steps ahead where as visual information of the “in the moment” swinging lower-limb and its relative position during the task is available in the lower visual field. This study determined exactly when visual information is utilised to control/update lead-limb swing trajectory during obstacle negotiation.
In this study, when the lower visual field was blocked out the foot-placement distance and toe-clearance became significantly increased, suggesting the brain overcorrecting for safety. A logical assumption. “These findings suggest that lower visual field input is typically used in an online manner to control/update final foot-placement, and that without such control, uncertainty regarding foot placement causes toe-clearance to be increased.”

http://www.ncbi.nlm.nih.gov/pubmed/22424759

And what have we been saying? parallel processing seems to be OK (balancing and reading), but dual or multitasking has its hazards…decreased speed of movement. not surprising because of the dual taskingincreased ankle dorsiflexion (not necess…

And what have we been saying? parallel processing seems to be OK (balancing and reading), but dual or multitasking has its hazards…

  • decreased speed of movement. not surprising because of the dual tasking
  • increased ankle dorsiflexion (not necessarily a bad thing. This is probably to create a wider and more stable base through pronation
  • reduced cadence
  • decreased stride length

we were surprised there was not a increased “base of gait”, as balance requirements increase, gait usually decomposes (see here for a cool post and video we did on this a while ago)

“Numerous studies have analyzed the impact of dual tasks—specifically, tasks that cause cognitive distraction—on gait. With regard to texting as a dual task, many studies have consistently found that it does have an effect on gait, and that’s mostly to slow a person down.


For instance, Italian researchers in the Journal of NeuroEngineering and Rehabilitation assessed 18 healthy young adults who did not have problems with vision, or neurological or musculoskeletal disorders that could affect their gait.3 Barefoot participants walked a straight path of 15 meters (about 50 feet) for three minutes under two conditions: walking alone and walking while texting.


They found that texting while walking differed from walking alone in terms of muscle activation, kinematics, and spatiotemporal variables. Texting was associated with delayed activation of the gastrocnemius lateralis muscle and slightly increased ankle dorsiflexion followed by slightly reduced plantar flexion. It was also associated with a slower gait speed, reduced cadence and stride length, increased flat-foot contact, and decreased push-off. The researchers also found increased co-contraction of the ankle antagonist muscles during what they called the “critical” gait phase—from load response to midstance, corresponding to the transfer of body weight from one leg to the other.”


its a short one. Take the time to check it out…


link to article: http://lermagazine.com/cover_story/texting-while-walking-gait-adaptations-and-injury-implications

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. 

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 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. 

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

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