February 2016

Texting while walking: Gait adaptations and injury implications

CoverPhotoIt’s not surprising that tactile interaction with a smartphone while walking can increase the risk of traumatic injury, but texting while walking also affects gait in ways that may ultimately have long-term effects.

By Shalmali Pal

Texting fails are funny—at least that’s the prevailing opinion on the Internet, which offers millions of videos and memes of ordinary folks tripping, falling, and face-planting while attempting to text, email, or engage in some other device-related activity, and walk simultaneously.

Of course, what these vignettes don’t reveal are any injuries sustained from texting while walking. A 2013 study in Accident: Analysis and Prevention found that the number of pedestrian emergency department visits for injuries related to cell phones tripled from 2004 to 2010, although the total number of pedestrian injuries dropped during that period.1 Texting while walking accounted for 9% of those injuries; given that the iPhone wasn’t introduced until 2007, that percentage can be expected to have increased.

A recent survey of more than 2000 US adults by the American Academy of Orthopaedic Surgeons (AAOS) reported that 28% of the respondents admitted to using a smartphone for texting or other nontalking tasks while walking, while 85% said they had seen others doing so.2 Nearly 40% said they had witnessed a distracted walking incident that resulted in an injury, and 26% had been involved in such an incident themselves.2

Distraction alone—not seeing a telephone pole until it’s too late, for example—can account for some injuries related to texting while walking, but such mobile multitasking also influences gait in ways that may ultimately have long-term effects.

Does slow equal steady?

iStock_000029794650_FullNumerous 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.

They attributed the findings to a central nervous system (CNS) adaptation under the dual-task condition in response to an increased need for ankle stabilization.

Lead author Valentina Agostini, PhD, a research assistant in the department of electronics and telecommunications of the Politecnico di Torino in Italy, told LER that she was somewhat surprised by the small reduction in speed (10%) associated with texting while walking in her group’s study, given that previous research put the reduction in walking speed during texting anywhere from 23% to 32%.4

But she also pointed out that the study design was different than previous experiments, which had participants type preassigned sentences or retype a phrase that appeared on the device’s screen. In her group’s study, the volunteers were asked to recall an event from the previous day, and then type a message about that event.

iStock_000079110983_Full“This kind of [recall] activity is rather typical when using WhatsApp, Facebook, etc. It implies that the subject does not just ‘type-type-type’…but rather ‘think and type’ while walking,” Agostini explained. “The volunteers most probably spent some time just thinking (without typing) since they had to remember what happened the day before, and decide which events they wanted to describe and how. This might explain the small velocity reduction observed. When they were thinking, they had more time to look at the path.”

In a paper in PLoS One, Sammy Licence, an MSc student at the University of Bath in the UK, and colleagues upped the ante by examining the impact of texting while walking and negotiating barriers, including a curb, uneven ground, traffic cones, stairs, and finally two dummies to maneuver around.5 The parameters they looked at during the dual task included step count, time, frequency, and length and barrier clearance.

The participants were adults aged 18 to 50 years, were not on any medications that could induce dizziness, and did not have any known problems with foot health or gait problems, according to coauthor Conrad Earnest, PhD, a research scientist in the department of health and kinesiology at Texas A&M University in College Station, and director of clinical research at Woodbolt International, a nutritional supplement company in Bryan, TX.

Overall, they reported that it took significantly longer for participants to complete the course—
because of slower walking speeds and shorter step lengths—while texting on their own phone, and while taking a math quiz on an iPhone supplied by the researchers (cognitive condition), versus walking alone. It also took people longer to negotiate the stairs during texting and the cognitive condition.

However, the volunteers also managed greater clearance heights while using a device versus walking alone. Notably, the incidence of making contact with a barrier—which would increase the risk of a trip or fall—did not differ significantly among the conditions, which surprised the researchers.

The results suggest “those who walk and text adopt a ‘protective’ gait pattern alteration in order to minimize the risk of potential accidents,” they concluded.

Finally, a study out of Australia in PLoS One analyzed gait in participants who walked on a straight line for 8.5 meters under three conditions: walking alone at a comfortable pace, walking at the same pace while reading a passage on a mobile phone screen, and walking while typing a predetermined phrase.6

The researchers looked at basic gait parameters, such as stride cycles (from right heel strike to the following right heel strike), and also analyzed how dual tasking affected postural stability through the pelvis and thorax. The young adult volunteers reported no neurological or musculoskeletal disorders that would impact gait.

Not surprisingly, the participants walked at a slower speed when they texted, even more so than when they read and walked. The absolute change in lateral foot position per stride was greater during reading and texting than walking alone, but that did not differ between the two phone tasks, the study found.

As for postural stability, they noted more mediolateral head motion, which has been linked to a greater risk of falling in older adults with Parkinson disease,7 during text­ing/reading while walking than during undistracted walking. The demands of manipulating a mobile phone may cause young healthy adults to prioritize movement of the head relative to the trunk at the expense of gait stability, the Australian researchers hypothesized. In short, the participants were more preoccupied with texting than they were with walking or maintaining balance and stability.

A new way to walk

If texting while walking does lead to gait changes, should lower extremity practitioners prepare for a future in which patients come to them with biomechanical problems that could be tied to routine texting and walking?

Experts say that’s not likely, and the “protective gait” that Licence and colleagues demonstrated is a big reason why.5

“I don’t believe that gait would be affected in the long run,” Earnest said. However, he noted that this protective gait shouldn’t be taken as a green light to text and walk with abandon.

An individual’s ability to make gait-related compensations when texting while walking doesn’t render the endeavor perfectly safe, because ambulation is a whole-body activity.

Absence-text-bubble

“It’s much like…any healthy ‘lifestyle habit.’ Eventually one has to exercise due diligence and self-protection,” he said. “It’s probably too pollyannaish to suggest that people learn to enjoy their walks and let the text and emails wait. Perhaps a good middle ground is that, if a text or email really can’t wait, then ‘pull to the side,’ stand still, answer the text or email, and continue along.”

Howard Osterman, DPM, a partner at Foot and Ankle Specialists of the Mid-Atlantic in Washington, DC, team podiatrist for the Washington Wizards of the National Basketball Association, and a spokesperson for the American Podiatric Medical Association, agreed that the protective gait will do its job the majority of the time. He also noted that the findings of Agostini et al demonstrate that gait changes during texting, but not necessarily for the worse.3

“In an effort to be a little more stable, everybody shortened their stride,” he noted.

When walking without distractions, a person focuses on what is ahead and takes longer strides, which require more heel-to-toe push off, Osterman said. When that focus is on a handheld device instead of what’s up ahead, a person will compensate with their gait.

“In an effort to counterbalance, you fire muscles that will plantar flex and dorsiflex to give you more stability, so you are getting a more rigid lever when you hit the ground,” he said. “Those muscles stayed fired for a longer period of time, so the midfoot was extended when they were texting.”

Agostini agreed with Osterman’s hypothesis about midfoot extension during the dual-task condition, noting that the “tibialis anterior tendon originates from the midfoot and controls dorsiflexion.” However, she cautioned that her group did not look specifically at midfoot extension in the study.

It’s certainly not unheard of for cultural or environmental changes in behavior to lead to gait adaptations, Osterman noted, citing the often-discussed differences between habitually barefoot individuals and habitually shod individuals as an example (see “The truth about barefoot running: It’s complicated,” November 2010, page 20).

“I think it’s the same…the body naturally adapts the gait for text­ing and walking,” he said.

But Osterman also emphasized that the ability to compensate doesn’t render texting while walking perfectly safe because ambulation is a whole-body activity.

“There are complimentary actions in the upper body that go along with gait, like the arm swing to help with stability,” he said. “When we evaluate people’s gait in the office, we’ll look for arm swing–sometimes you’ll see one arm swinging more than the other, and that’s often a manifestation of limb length discrepancy or some other problem.8,9 If you’ve got two-handed texting happening, then the arm swing is lost, and that can change whole-body dynamic stability during walking.”

Agostini hypothesized that long-term gait changes may take place, but they won’t necessarily be detrimental. She cited her teenage daughter as an example of how people adapt gait to their activities of daily living.

“She feels completely comfortable walking, typing on her smartphone, and talking to me at the same time,” Agostini explained. “Young people probably spend most of their time double- or triple-tasking. If the double-task of texting and walking is practiced on a daily basis, it is most likely going to have a long-term effect on gait. It is an exercise, after all.”

The more people text and walk, the more adept they become at that protective gait, and the CNS then adapts as well, Agostini hypothesized.

“Hence, it would not be surprising to observe a changed motor scheme in the walking pattern of young individuals who are constantly ‘training’ at walking while texting,” she said.

Interestingly enough, in the AAOS survey, only 3% of the respondents reported breaking bones as a result of a distracted walking incident. This relatively low number would seem to jibe with the idea of a protective gait, said Alan Hilibrand, MD, an AAOS spokesperson, and director of medical education for the department of orthopedic surgery at the Rothman Institute in Sewell, NJ, and Jefferson Medical College in Philadelphia.2

Still, Hilibrand joined his colleagues in stressing caution.

“People are probably a little more careful [when texting and walking], but it’s not going to prevent these injuries from happening. I’d recommend what the AAOS advocates for: If you need to text, stop, find a safe place that is out of the way, text or email, and then continue walking,” he said.

The age issue

All of the studies above looked at relatively young adults (although Licence and colleagues did include participants up to age 50 years), so it remains uncertain how older people would fare under the same conditions.

But some data indicate this kind of dual task may be best left to younger folks. According to the AAOS survey, among those who reported injuries during distracted walking, women age 55 years and older were the subgroup most likely to have been injured, while millennials (18 to 34 years) were least likely.2

iStock_000080655525_FullA study done in Israel in healthy people, aged 30-77 years, reported that when completing a dual task—walking while solving a simple math problem without the use of any device—older adults walked more slowly and with more stride variability than their younger counterparts. Also during the dual task, their arm swing decreased while arm swing asymmetry increased.10

“Healthy walking is characterized by pronounced arm swing and axial rotation…that arm swing improves stability especially in response to perturbations,” the authors wrote.

If texting while walking is a type of perturbation, experts agree, it’s an unwise activity in older people.

“As we age, balance becomes an issue,” Osterman pointed out. “Then you add in concomitant risk factors, say a person with type 2 diabetes and a history of neuropathy. They have a loss of proprioception, and with that loss, the chance of a fall increases. Really, anything that changes our balance could put us at risk for falls and injury.”

Asked if studies on texting and walking in older adults would be worthwhile, Agostini suggested that designing such a study would be “rather cumbersome,” as all the comorbidities that can accompany aging must be taken into consideration.

“As an example, when trying to write on a smartphone (or just trying to read it, like many other middle-aged people, I suffer from presbyopia (plus myopia). So, when doing this while walking, I have to take my glasses off,” she explained. “This means keeping glasses in one hand, and the smartphone in the other while trying not to stumble. As a matter of fact, I try to avoid this situation.”

But it seems older people are following Agostini’s lead. According to the AAOS survey, millennials are more likely to report engaging in common distracted walking behaviors than older people.2

From Osterman’s perspective, the real area of concern isn’t older people so much as children and adolescents, who are still developing physically. The long-term effect of texting while walking in these “digital natives”11 may not happen directly in the lower limbs, but frther up the kinetic chain.

“When a person is in physical development, the activities they do can create long-term joint changes,” Osterman noted. “Those changes may be happening because of long periods of sitting in front of a computer or video game, coupled with a lack of exercise. If texting while walking becomes so prevalent that it leads to neck, shoulder, and back issues, that could secondarily affect gait.”

His main concern is with kyphosis, which studies suggest can have a negative impact on gait12 and mediolateral dynamic stability of the trunk. The forces experienced by the cervical spine as the head is tilted forward for prolonged periods of device use13 may also lead to gait-related fallout.

“That could change the gait pattern, although that happens over time. That may be a long-term risk,” Osterman said.

Perhaps the ultimate answer to making texting while walking less hazardous would be for society to adapt. Agostini pointed out that in 2014, the National Geographic TV channel laid down “smartphone sidewalks,” or lanes specifically dedicated to people who must walk and be on their devices at the same time, in cities in China and the US.14,15 Although the lanes were temporary, as part of a TV show, dedicated spaces for “smartphone addicts” may be the best way to reduce the risks of texting while walking, Agostini said.

“In general, I would not encourage people to text while walking outdoors,” she said. “The more our sight and attention is split among several tasks, the higher the risk.”

Shalmali Pal is a freelance writer based in Tucson, AZ.

REFERENCES
  1. Nasar JL, Troyer D. Pedestrian injuries due to mobile phone use in public places. Accid Anal Prev 2013;57:91-95.
  2. American Academy of Orthopaedic Surgeons. Distracted walking study. 2015. http://www.anationinmotion.org/wp-content/uploads/2015/12/AAOS-Distracted-Walking-Topline-11-30-15.pdf
  3. Agostini V, Lo Fermo F, Massazza M, et al. Does texting while walking really affect gait in young adults? J Neuroeng Rehabil 2015;12(1):86.
  4. Plummer P, Apple S, Dowd C, et al. Texting and walking: Effect of environmental setting and task prioritization on dual-task interference in healthy young adults. Gait Posture 2015;41(1):46-51.
  5. Licence S, Smith R, McGuigan MP, Earnest CP. Gait pattern during walking, texting and walking and texting during cognitively distractive tasks while negotiating common pedestrian obstacles. PLoS One 2015;10(7):e0133281.
  6. Schabrun SM, van den Hoorn W, Moorcroft A, et al. Texting and walking: strategies for postural control and implications for safety. PLoS One 2014;9(1):e84312.
  7. Cole MH, Silburn PA, Wood JM, et al. Falls in Parkinson’s disease: kinematic evidence for impaired head and trunk control. Mov Disord 2010;25(14):2369-2378.
  8. Wu U, Li Y, Liu AM, et al. Effect of active arm swing to local dynamic stability during walking. Hum Mov Sci 2015;45:102-109.
  9. Starkey C, Brown SD. Examination of Orthopedic & Athletic Injuries.. 4th ed. F.A. Davis Co., Philadelphia, 2015.
  10. Mirelman A, Bernad-Elazari H, Nobel T, et al. Effects of aging on arm swing during gait: the role of gait speed and dual tasking. PLoS One 2015;10(8):e0136043.
  11. Oliver J. What does it mean to be a digital native? CNN.com, Dec. 8, 2012.http://www.cnn.com/2012/12/04/business/digital-native-prensky/
  12. Sangtarash F, Manshadi FD, Sadeghi A. The relationship of thoracic kyphosis to gait performance and quality of life in women with osteoporosis. Osteoporos Int 2015;26(8):2203-2208.
  13. Hansraj K. Assessment of stresses in the cervical spine caused by posture and position of the head. Surg Technol Int 2014;25:277-279.
  14. Orf D. A smartphone sidewalk pops up on a busy street in China. Gizmodo.com, Sep. 14, 2014. http://gizmodo.com/smartphone-sidewalks-pop-up-on-a-busy-street-in-china-1634549907
  15. Pegoraro R. Cellphone talkers get their own sidewalk lane in D.C. Yahoo.com, July 17, 2014. https://www.yahoo.com/tech/cellphone-talkers-get-their-own-sidewalk-lane-in-d-c-92080566744.html
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One Response to Texting while walking: Gait adaptations and injury implications

  1. Excellent analysis. I hope mobile Tech Savvy population absorb this in their brain

    Well done Shalmali Pal

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