Thinking while walking changes arm swing...

Maybe we should keep this in mind while "gait retraining" and "rehabbing". You could be inducing the changes you are seeing on a cortical level. 

This makes you wonder about walking and thinking about sometime else. Being mindful has its advantages, like less cortical laterality and dominance. Remember, in this study, the arm swing is les on the right, so theoretically, less cortical motor drive from the left side. No wonder your gait changes! Be careful which hand you are texting with : )...Better yet, don't walk and text....

Human arm swing looks and feels highly automated, yet it is increasingly apparent that higher centres, including the cortex, are involved in many aspects of locomotor control. The addition of a cognitive task increases arm swing asymmetry during walking, but the characteristics and mechanism of this asymmetry are unclear. We hypothesized that this effect is lateralized and a Stroop word-colour naming task-primarily involving left hemisphere structures-would reduce right arm swing only. We recorded gait in 83 healthy subjects aged 18-80 walking normally on a treadmill and while performing a congruent and incongruent Stroop task. The primary measure of arm swing asymmetry-an index based on both three-dimensional wrist trajectories in which positive values indicate proportionally smaller movements on the right-increased significantly under dual-task conditions in those aged 40-59 and further still in the over-60s, driven by reduced right arm flexion. Right arm swing attenuation appears to be the norm in humans performing a locomotor-cognitive dual-task, confirming a prominent role of the brain in locomotor behaviour. Women under 60 are surprisingly resistant to this effect, revealing unexpected gender differences atop the hierarchical chain of locomotor control.

R Soc Open Sci. 2017 Jan 25;4(1):160993. doi: 10.1098/rsos.160993. eCollection 2017 Jan.
Increasing cognitive load attenuates right arm swing in healthy human walking.
Killeen T1, Easthope CS1, Filli L2, Lőrincz L2, Schrafl-Altermatt M1, Brugger P2, Linnebank M3, Curt A1, Zörner B1, Bolliger M1.

free full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319362/

Your Gait Changes when you text....

Does texting alter your gait? It sure seems to slow you down, and according to this study, alter firing patterns of muscles about your ankle. Perhaps you are trying to preserve ankle rocker and maintain stability? It is interesting that ankle dorsiflexion actually increased and plantar flexion decreased.

"Young adults showed, overall, small gait modifications that could be mainly ascribable to gait speed reduction and a modified body posture due to phone handling. We found no significant alterations of ankle and knee kinematics and a slightly delayed activation onset of the left gastrocnemius lateralis. However, we found an increased co-contraction of tibialis anterior and gastrocnemius lateralis, especially during mid-stance. Conversely, we found a reduced co-contraction during terminal stance."

link to FREE FULL TEXT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579642/

When you text while walking, you may be a hazard to yourself and others

Watch where you step... We have trouble while dual tasking with visual, attentional deficits. In other words, you don't see stuff. That's probably one of the reasons they are trying to ban texting while crossing the street in Honolulu.

"The results revealed that the size of visual field and visual acuity demand were varied across the visual task conditions. Approximately half of the visual cues provided during texting while walking were not perceived as compared to the visual task only condition. The field of regard loss also increased with increased dual-task cost of mobile phone use. Dynamic walking stability, however, showed no significant differences between the conditions. Taken together, the results demonstrate that the loss of situational awareness is unavoidable and occurs simultaneously with decrements in concurrent task performance. The study indicates the importance of considering the nature of attentional resources for the studies in dual-task paradigm and may provide practical information to improve the safe use of mobile phones while walking."

Lim J, Chang SH, Lee J, Kim K. Effects of smartphone texting on the visual perception and dynamic walking stability. Exerc Rehabil. 2017 Feb 28;13(1):48-54. doi: 10.12965/jer.1732920.460. eCollection 2017 Feb.  link to full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331999/

http://www.npr.org/sections/thetwo-way/2017/07/29/540140824/its-now-illegal-to-text-while-crossing-the-street-in-honolulu

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