Elsevier

Applied Ergonomics

Volume 84, April 2020, 103009
Applied Ergonomics

Mobile phone use impairs stair gait: A pilot study on young adults

https://doi.org/10.1016/j.apergo.2019.103009Get rights and content

Highlights

  • A novel dual-task paradigm was used: stair negotiation while talking on the phone.

  • Stair gait performance was affected by talking on the phone in young participants.

  • With phone conversation, participants were slower and reduced the motor control cost.

  • These gait changes are consistent with a difficulty in integrating the two tasks.

Abstract

Human movement control requires attention to accurately tune motor commands in response to environmental changes. Dual task paradigms are used to test the role of attention on motor performance. Usually the tasks used have little resemblance with every day experience. Here we ask: Does a common cognitive task, such as a mobile phone conversation, compromise motor performance on stairs?

Eight young participants negotiated an instrumented seven-step staircase. Stair negotiation while talking on a mobile phone was compared to normal stair negotiation. Stepping parameters, jerk cost (measure of smoothness of locomotion) and step clearance were measured.

When talking on a mobile phone, participants’ overall body velocity (mean(sd): Ascent 0.534(0.026) vs 0.511(0.024) m/s, Descent 0.642(0.026) vs 0.511(0.024) m/s, No phone/Phone respectively) and cadence decreased significantly (Ascent 75.8(5.8) vs 65.6(4.4) steps/min, Descent 117.4(4.2) vs 108.6(6.0) steps/min, No Phone/Phone respectively). Pelvis and feet jerk cost also changed significantly, mostly decreasing with phone use. Foot clearance did not show significant changes between No Phone and Phone conditions.

These pilot results show that, even for young, healthy and cognitively intact individuals, talking on a mobile phone whilst negotiating a staircase induces measurable changes in motor performance. Participants moved slowly but more smoothly, reducing the motor control cost, possibly at the expense of movement accuracy. The reduction in motor performance is likely to be due to the difficulty in integrating the two sub-tasks. These results suggest that even young, healthy individuals show stair gait impairment when simultaneously negotiating stairs and performing another cognitive task, such as talking on the phone.

Introduction

Human motor tasks such as standing, walking (Lajoie et al., 1993; Woollacott and Shumway-Cook, 2002) and stair negotiation (Madehkhaksar and Egges, 2016) require attention. Individuals often multitask, for example they walk while having a conversation in person or on the phone. Multitasking involves divided attention and consequently performance is affected, indicating a strong link between cognitive load and motor control (Madehkhaksar and Egges, 2016; Verghese et al., 2007; Nasar et al., 2008; Lamberg and Muratori, 2012; Plummer et al., 2015).

Multitasking can be investigated using dual-task tests. Traditionally, two main paradigms have been used: real-life observations and laboratory-based experiments. Real-life observations are not artificial, but the quantities that can be measured are limited (e.g. increased time spent crossing the road whilst talking on a mobile phone) (Hatfield and Murphy, 2007). Laboratory-based studies accurately quantify standing or walking, but the cognitive tasks used are not necessarily real, such as arithmetic and spelling tasks, spatial and non-spatial memory tasks or memorising word lists (Pellecchia, 2003). The present study exploited the benefits of both paradigms and a new protocol was designed to investigate two real-life tasks, talking on the phone and stair negotiation, in the laboratory. This approach is promising because quantification is needed in this research field. However, here we used phone conversation rather than texting or typing (Demura and Uchiyama, 2009; Licence et al., 2015; Schabrun et al., 2014) because we aimed to measure the effect of the conversation without involving the visuo-motor interference as in texting (Timmis et al., 2017; Ioannidou et al., 2017).

Unspecified telephone use is related to ~11,000 home and leisure accidents in the UK per year (HASS and LASS, 2002). This report is more than a decade old, and it is highly likely that the increase in phone use may be related to a higher number of accidents. Talking on a mobile phone has been highly studied in conjunction with driving (Strayer and Johnston, 2001; Patten et al., 2004), walking (Nasar et al., 2008; Lamberg and Muratori, 2012; Plummer et al., 2015) or crossing the road (Neider et al., 2010, 2011; Stavrinos et al., 2011; Schwebel et al., 2012). Performance was negatively affected by mobile phone use, as measured by increased time to complete the task and risky behaviours. No difference was found between hand-held and hand-free mobile phones (Nasar et al., 2008; Strayer and Johnston, 2001). This suggests that diversion of attention and the conversation itself interfere with encoding of information in working memory (Neider et al., 2010), where new and stored information are processed during reasoning, comprehension and memory updating.

Stair negotiation was chosen as the simultaneous motor task here. Compared to level walking, stair negotiation poses a higher musculo-skeletal load to move the body mass forwards and up/downwards with concentric and eccentric muscle contractions, and challenges balance control and coordination of muscles in the single support phase (in particular during descent) (Madehkhaksar and Egges, 2016; Riener et al., 2002; Reeves et al., 2008, 2009). Stair negotiation is often investigated because falls are common when negotiating a staircase, with about 300,000 accidents per year on the stairs in the UK alone (HASS and LASS, 2002). Stair negotiation is a suitable motor task because it requires attention and planning and potentially error correction; working memory and information processing are engaged to respond to changes in the environment.

The two tasks chosen here (phone conversation during stair negotiation) require attention, do not increase difficulty indiscriminately and thus avoid floor or ceiling effects (Schaefer and Schumacher, 2010), and are fairly common, which excludes learning and habituation components that could affect the results. In the present pilot study, a small group of young participants were tested using this novel protocol to measure if and how talking on a mobile phone affects stair locomotion.

We hypothesise that stair negotiations will show changes when talking on the phone consistent to a compensatory method to reduce fall risk, even in a population of young adults. Such changes, reflecting the increased difficulty of an ecological cognitive task on movement control for a healthy young population, would be of greater concern to populations with decreased cognitive and physical capacity.

Section snippets

Ethical approval

Participants gave written informed consent to this experiment which conformed to the standards set by the Declaration of Helsinki and was approved by the ethics committee of the Faculty of Science and Engineering, Manchester Metropolitan University.

Participants and procedure

Eight healthy young participants with no history of brain injury or other neurological conditions were tested (six males, two females; mean (standard deviation ‘SD’); age, 27(4) years; height, 1.75(0.12) m; mass, 74.2(18.2) kg, self-reported leg and

Results

All participants freely held the mobile phone in their dominant hand. The ambidextrous participant held the mobile phone in her left hand. Participants never used the handrails.

Discussion

In this pilot study, a novel dual-task paradigm was used to test the effect of a cognitive task on motor performance during stair negotiation. We found that having a conversation over the phone induced changes in gait performance even in a group of young healthy participants.

Author contributions

The experiments were performed at the Laboratory of Biomechanics, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK. All the authors contributed to design of the work. IDG contributed to the conception of the experiment, data acquisition, analysis and interpretation. IDG wrote the article. All authors contribute to the critical review of the manuscript and approved the final version.

Funding

This study was supported by the New Dynamics of Ageing (RES-356-25-0037).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

We thank the anonymous participants for taking part to this experiment. We also thank Emily Kingdon for support with the data collection and Alexander Ireland for his technical support.

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