Face Time Or Face Plant


Science Communication Blog Post Competition

Second Place Winner
Pavlo Zerebecky

Have you ever found yourself glued to your phone? Better question, have you ever tripped over something because you were glued to your phone? Walking while distracted can have the consequences of improperly recognizing your environment and making the proper adjustments to avoid a stumble or fall. Our body contains a circuitry, known as Central Pattern Generators (CPG’s), inside the spinal cord which use sensory feedback from our muscles and skin to create the alternating actions of your legs and arms during walking, running, and swimming. This mechanism is available to us regardless of whether we concentrate on the individual limbs during these rhythmic type movements. But what if our environment is unpredictable? Does the spinal cord contain the ability to avoid obstacles and change the variation of our steps to prevent falling?

A group of researchers investigated these questions using a treadmill walking experiment with four conditions: normal walking, two multi-tasking conditions of different difficulty, and a reduced vision condition. The participants walked on a treadmill while looking at a screen in front of them. For the normal walking condition, the participants walked on the treadmill while looking at a fixed cross on the screen in front of them. For the multi-tasking conditions, the participants identified the colour of a word displayed on a screen in front of the treadmill. The easier of the two conditions displayed the name of the colour in which the word was written, for instance the word “blue” was written in the colour blue. The more difficult condition displayed the word in a colour that did not match the written word, for example, the word ‘red’ written in a blue font would be properly identified as blue. For the reduced vision condition, the participants walked on the treadmill while wearing glasses that blocked their lower visual field.

The experiments used cameras to track the participants movement to determine the minimum vertical distance between the ground and the highest point of the big toe, or toe clearance, while the leg swings through during walking. Minimum toe clearance is related to tripping, for example a smaller toe clearance would increase the likelihood of tripping as the big toe may make contact with an object during walking. The experimenters found that during the multi-tasking conditions, the participants toe clearance was greatly reduced. This means that the distance between their big toe and the ground while taking a step forward was less during these conditions.


In order to move in an uncertain environment, visual information is required. The brain uses visual information and is then able to recognize potential obstacles. Different parts of the brain would work together to plan the change in height or placement of the step to avoid tripping. The brain translates this plan and sends a command to the spinal cord where it instructs the muscles to make a corrective step if necessary. Multitasking reduces the attention directed to the brain to make these adjustments to walking. As walking can be involuntarily generated in the spinal cord, the brain then focuses attention on what we are looking at during the multitasking conditions. In other words, the demands of walking and the visual task compete for the brain’s attention.


Research and personal experience has shown that falling is a common cause of injury. For younger adults, this may not be a huge concern, but as we age, falling can be problematic. In elderly individuals, who are more prone to tripping and falling, the injuries related to falls can lead to death. This research study supports this statement as the experimenters also performed these four conditions in participants of varying age. Minimum toe clearance was further reduced in elderly individuals in the multi-tasking conditions. The events occurring in the body as we age can lead to losses of strength, coordination, and balance. This can be further reduced through illness and disease. Under these circumstance, the attentional requirement from the brain to control movement is much greater. When multi-tasking is required of the elderly, there is a competition between whether to focus on walking or what they see. The brain has difficulty keeping up with all these demands. This can interfere with an elderly person’s ability to make corrective movements if necessary and can lead to a tumble. The importance of these findings is to be aware of your surroundings, especially during walking. So, the next time you’re out for a walk and you want to check your phone, think if that face plant is really worth the face time.


Killeen T, Easthope CS, Demkó L, Filli L, Lőrincz L, Linnebank M, Curt A, Zörner B, & Bolliger M. (2017). Minimum Toe Clearance: Probing the Neural Control of Locomotion. Scientific Reports, 7(1).

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