Contents lists available at ScienceDirect Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost Full length article Local dynamic stability and gait variability during attentional tasks in young adults Rina Márcia Magnani a, ⁎ , Georgia Cristina Lehnen a , Fábio Barbosa Rodrigues a , Gustavo Souto de Sá e Souza a , Adriano de Oliveira Andrade b , Marcus Fraga Vieira a a Universidade Federal de Goiás, Bioengineering and Biomechanics Laboratory, Goiânia, Goiás, Brazil b Universidade Federal de Uberlândia, Biomedical Engineering Laboratory, Uberlândia, Minas Gerais, Brazil ARTICLE INFO Keywords: Human gait Cell phone Dual-task Kinematics Local dynamic stability Entropy ABSTRACT Cell phone use while walking may be a cognitive distraction and reduce visual and motor attention. Thus, the aim of this study was to verify the effects of attentional dual-tasks while using a cell phone in different conditions. Stability, regularity, and linear variability of trunk kinematics, and gait spatiotemporal parameters in young adults were measured. Twenty young subjects of both genders were asked to walk on a treadmill for 4 min under the following conditions: (a) looking forward at a fixed target 2.5 m away (walking); (b) talking on a cell phone with unilateral handling (talking); (c) texting messages on a cell phone with unilateral handling (texting); and (d) looking forward at the aforementioned target while listening to music without handling the phone (listening). Local dynamic stability measured in terms of the largest Lyapunov exponent decreased while handling a cell phone (talking and texting). Gait variability and regularity increased when talking on a cell phone, but no variable changed in the listening condition. Under all dual-task conditions, there were significant increases in stride width and its variability. We conclude that young adults who use a cell phone when walking adapt their gait pattern conservatively, which can be because of increased attentional demand during cell phone use. 1. Introduction Attention and executive functions from cognitive areas are active during gait motor control. Performing gait in conjunction with another task, such as talking or typing on a cell phone, requires cognitive, neuromotor, physical, and memory skills; in addition, there is a competition for visual attention between the two tasks [1–4]. Thus, the dual-task paradigm has been used to evaluate the role of concurrent attentional demand in the motor control of human gait; in this setting, increased risk of falling, kinematic variability, and gait instability were observed [5–7]. Studies showed that dual-tasks using the cell phone, including texting, reading, and playing logical games, have an impact on the locomotion motor ability [1,2,8,9]. However, such dual-tasks are not executed spontaneously. To date, dual-tasks routinely practiced by young people using the cell phone have not been investigated, includ- ing unilateral handling texting and talking, and listening to music. According to TeleGeography, in 2013, 77% of the people worldwide used cell phone text messaging as a communication method. In 2015, there were 7.1 billion active devices, and there were 7.3 billion people [10]. When using a cell phone, individuals need to focus on a small portable screen, which requires increased levels of manual dexterity, head and neck flexion, and concentration, all of which leads to reduced visual information input from the individual’s surroundings, increased working memory use, and executive control requirement [9,11]. Furthermore, several studies have shown the dangers of concurrent cell phone use while driving or walking, which may lead to an accident [1] or even death [2,8,11]. To maintain stability, executive and attention functions alter gait patterns during dual-task walking, as reported in young adults walking on a treadmill while using a cell phone [9]. In addition, when walking overground, the dual-task paradigm using cell phone increased the variability in spatiotemporal gait parameters, which has been related to decreased walking speed [2,8,10,12,13]. Schabrun et al. [10] also found increased trunk variability when individuals walked on a tread- mill with a constant speed that was equal to normal the over-the- ground speed [10]. Similarly, Kao et al. [1] found a significantly greater trunk variability in treadmill walking during dual-task while using cell phone. Although studies evaluating regularity while walking and dual- task are scarce, one study was an examination of the effect of cell phone texting on the postural stability of young adults; the results from this http://dx.doi.org/10.1016/j.gaitpost.2017.04.019 Received 27 June 2016; Received in revised form 12 April 2017; Accepted 13 April 2017 ⁎ Corresponding author. E-mail address: rinamagnani@gmail.com (R.M. Magnani). Gait & Posture 55 (2017) 105–108 0966-6362/ © 2017 Elsevier B.V. All rights reserved. MARK