Impact of mobile phone use on accidental falls risk in young adult pedestrians

Abstract

Background: Mobile phone use is known to be a distraction to pedestrians, increasing their likelihood of crossing into oncoming traffic or colliding with other people. However, the effect of using a mobile phone to text while walking on gait stability and accidental falls in young adults remains inconclusive. This study uses a 70 cm low friction slip hazard and the threat of hazard to investigate the effects of texting while walking on gait stability, the ability to recover balance after a slip hazard and accidental falls.

Methods: Fifty healthy young adults performed six walking tasks, and one seated texting task in random order. The walks were conducted over a 10-m walkway. Four progressive hazard levels were used: 1) Seated; 2) Normal Walk (walking across the walkway with no threat of a slip); 3) Threat (walking with the threat of a slip); and 4) Slip (walking with an actual 70 cm slip hazard). The three walking conditions were repeated twice with and without the mobile phone texting dual-task. Gait kinematics and trunk posture were recorded using wearable sensors attached to the head, trunk, pelvis and feet. Study outcomes were analyzed using repeated measures analysis of variance with significance set to P≤.05.

Results: Mobile phone use significantly impaired postural balance recovery when slipping, as demonstrated by increased trunk sway. Mobile phone use negatively impacted gait stability as demonstrated by increased step time variability and decreased harmonic ratios. Increased hazard levels also led to reduced texting accuracy.

Conclusions: Using a mobile phone to text while walking may compete with locomotor tasks, threat assessment and postural balance control mechanisms, which leads to an increased risk of accidental falls in young adults. Pedestrians should therefore be discouraged through new educational and technology-based initiatives (for example a "texting lock" on detection of walking) from texting while walking on roadside footpaths and other environments where substantial hazards to safety exist.

Keywords: Accident; Balance; Dual-task; Fall; Gait; Pedestrian; Phone; Road safety; Texting; Walking; Wearable.

Fig. 1

The perturbation walkway system with the 70 cm low friction slip hazard at tile five.

Fig. 2

Sensor attachments, local sensor axes, trunk rotation convention and step detection.

Fig. 3

Sensor data shows an “accidental fall” from a slip hazard while texting. During each walk, postural balance was measured by trunk angle (in degrees), gait regularity was measured by vertical (VT) acceleration of the pelvis (meters per second squared) and heal strikes (HS) indicated at the start of each foot contact. Walk order was randomised. [A] Normal Walk condition (the participant was reassured that “there would be no slip”). [B] Threat condition (the participant was told “there may or may not be a slip” and they were blinded while we set the slip tile locking mechanism). For this walk the anticipatory gait adaptation was to progressively lean forward (downward trend of top line). At 3.4 s, the third right tile did not slip. [C] Slip condition (the participant was told “there may or may not be a slip”). The third right tile slipped. The participant lost balance posteriorly and then overcompensated anteriorly.

Fig. 4

Changes in texting performance, gait and balance recovery (means ± 1 standard error). Texting while waking significantly impaired postural balance recovery and gait stability with increased hazard levels negatively impacting on texting accuracy. [A] (§) Indicates significant differences in texting performance between the Seated and Normal Walk; the Normal Walk and Threat, and the Threat and Slip hazard levels. [B, C and D] (¶) Indicates significantly (P≤.05) slower and more variable gait with longer dual stance times in the Slip condition compared to the Normal Walk and Threat conditions. (†) Indicates the texting dual-task led to significant (P≤.05) gait deterioration at all hazard levels. [E] (#) Indicates the texting dual-task led to significantly (P≤.05) greater risk of falling as indicated by increased trunk pitch range in the Slip condition, but not in the Normal Walk or Threat conditions. [F, G and H] (‡) Indicates a significant (P≤.05) interaction effect of reduced gait stability (indicated by lower harmonic ratio) between increasing hazard levels and the texting dual-task.