Runners: Protect Your Legs with Fewer Distractions
Article ID: 668836
Released: 6-Feb-2017 8:00 AM EST
Source Newsroom: Association of Academic Physiatrists (AAP)

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Las Vegas — Runners who encounter visual and auditory distractions may be more likely to sustain leg injuries, according to research presented this week at the Association of Academic Physiatrists Annual Meeting in Las Vegas.

Runners often seek distraction from the task at hand. Whether it be music, texting, daydreaming, taking in the sights, or propping a book up on the treadmill, more often than not a distraction is welcome. But, researchers from the University of Florida have recently discovered those distractions may lead to injury.

“There isn’t a lot of research that looks at the connections between cognitive stressors, or distractions, and injury risk, says Daniel Herman, MD, PHD; assistant professor at University of Florida Department of Orthopedics and Rehabilitation and lead investigator in the study. “This is an important topic to study as runners commonly attend to distractions such as music, crowd noise, or other runners.”

Dr. Herman’s team looked at the effect of auditory and visual distractions on 14 runners to determine what effect, if any, these distractions would have on things such as how much a runner breathes per minute and how much of that oxygen is utilized by the body, heart rate, the amount of energy expended, running rhythm, the length and width of steps, the speed in which runners apply force to their bodies, and the force the ground applies to the runners’ bodies when they come in contact with it.

The runners – eight men and six women – were all injury free at the time of the study, and they were approximately 26 years old. On average, the runners logged 31 miles each week.

Dr. Herman’s team had each participant run on a treadmill three separate times. The first time was without any distractions. The second time added a visual distraction, which consisted of the runner concentrating on a screen displaying different letters in different colors with the runner having to note when a specific letter-color combination appeared. The third time added an auditory distraction similar to the visual distraction, with the runner having to note when a particular word was spoken by a particular voice.

When compared to running without distractions, the participants had faster application of force to their left and right legs (called loading rate) with auditory and visual distractions. They also experienced an increased amount of force from the ground (called ground reaction force) on both legs with auditory distractions. Finally, the runners tended to breathe heavier and have higher heart rates with auditory and visual distractions than without any distractions at all.

“Running in environments with different distracting features may adversely affect running performance and injury risk,” explains Dr. Herman. “Sometimes these things cannot be helped, but you may be able to minimize potentially cumulative effects. For example, when running a new route in a chaotic environment such as during a destination marathon, you may want to skip listening to something which may require more attention – like a new song playlist or a podcast.”

Dr. Herman’s team will continue to investigate the potential relationship between distracted running and leg injuries, including the characteristics of runners who may be more or less susceptible to this effect, and any effect this relationship has on different training techniques that use auditory or visual cues.
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The Effect of Visual and Auditory Attention Tasks on Biomechanical and Metabolic Performance during Running

Daniel C. Herman, MD, PHD; Andrew Harris, BS; Christopher Massengill, MS; Cong Chen, MS; Trevor Leavitt, BS; Heather Vincent, PHD

Objectives: Cognitive stressors can increase lower extremity injury risk by altering biomechanics. It is unknown whether these stressors adversely impact running motion or physiological responses. This evidence gap is significant because runners commonly attend to distractions such as music, crowd noise, and visual signals in the environment. This study investigated the effect of dual-attention tasks on key biomechanical and metabolic measures of running performance.

Design: This was an experimental, repeated measures design. Fourteen injury-free runners (8M, 6F; Age 25.7±5.8 yrs; Weekly distance 47.8±16.0 km) ran on an instrumented treadmill for three conditions: control (CON), visual distractor (VD), and auditory distractor (AD). Metabolic data were collected using a portable gas analyzer, including oxygen consumption, minute ventilation, heart rate, and energy expenditure. Biomechanical data were collected via 3D videographic techniques, and included cadence, step length, step width, vertical ground reaction force, and loading rate. Data were analyzed using repeated measures analysis of variance and paired-t tests for post-hoc analysis with alpha set a priori at 0.05.

Results: Compared to CON, the impact loading rate was higher for the AD and VD for the left limb (in N/s: 41.2±18.2 versus 45.2±19.7 and 44.5±19.9, respectively; p < 0.05) and the right limb (in N/s: 39.2±13.7 versus 46.3±17.3 and 46.5±17.1, respectively; p < 0.05). Ground reaction forces increased for the AD condition only for both the left limb (in N/kg: CON 25.4±3.4; AD 26.1±3.0, p=0.028; VD 25.7±3.3, p=0.395) and the right limb (in N/kg: CON 25.4±3.3; AD 26.2±3.1, p=0.019; VD 25.7±3.3, p=0.322). Compared to CON, average minute ventilation was 4.5% and 5.7% greater for AD and VD, respectively (p=0.001). Average heart rates were 2.8%-3.4% higher in the VD and AD compared to CON (p=0.005).

Conclusions: Attending to visual and auditory distractors increases lower extremity loading and physiological demand. Running in well-versed conditions may potentially reduce injury risk and improve running performance.