# The Impact of Using Mobile Phones on Gait Characteristics: A Narrative Review
## 2 Participant Characteristics and Study Design
### Independent Variables Base on Different Mobile Phone Functions  
Then, the independent variables from the 29 studies were classified and summarized (Table 2). Using mobile phones to send messages in different ways (email, message apps, editing, etc.) was the most frequently tested task (87.09%), followed by talking (35.48%), reading (22.58%), surfing the Internet (9.68%) and gaming (9.68%). Sixteen studies tested the effects of a single mobile phone function on gait and the remaining thirteen studies compared the differences between the impacts of various mobile phone use tasks.  
Although more than half of the studies used the task of texting to test the impacts of mobile phone usage on gait, the designed texting tasks are quite different. This review divided those tasks into three levels (low, medium and high cognitive tasks) based on the difficulty of the task (Figure 1). The low cognitive tasks just required the subjects to type. For instance, subjects were required to send \"Good Morning\" via mobile phone while walking [14] or to continuously hit the space button at the fastest speed to evaluate their maximum click speed [3]. Medium cognitive tasks included texting answers to simple  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Table**} & \multicolumn{4}{c}{**Dependent Variables of Sports Biomechanics**} \\ \cline{2-5}  & **Velocity** & **Cadence** & **Stride** & **Step** & **Step** & **Stride** & **Double** \\  & **(Speed)** & **Length** & **Length** & **Width** & **Time** & **Time** & **Time** \\ \hline Walking when & \(\downarrow\) & \(\downarrow\) & \(\downarrow\) & & & \\   using a phone (texing) vs. & [12, 13, 17, 18, 20, 22, 23, 24, 25, 26, 28, 27, 28, 29, 30, 31, 34, 36, 37, 38] & [12, 17, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38] & [17, 26, 33, 36, 37, 32, 34, 35, 34, 36, 37, 38] & [14, 24, 32, 25, 26, 27, 28, 31, 32, 34, 35, 36, 34, 37, 34, 36, 38] \\ Walking when & \(\downarrow\) & \(\downarrow\) & \(\downarrow\) & \(\uparrow\) & & \\   using a phone (talking) vs. & [19, 22, 23, 39, 30, 31] & [23, 31, 23, 31] & [16, 23, 32, 27] & & \(\uparrow\) [20, 31] \\   normal walking & & & & & 27 & \\   Walking when & & & & & \\   using a phone (listening) vs. & \(\downarrow\) [22] & \(\downarrow\) [22] & & \(\uparrow\) [27] & \\   normal walking & & & & & \\   Walking when & & & & & \\   using a phone (listening) vs. & \(\downarrow\) [28, 29, 30, 38] & \(\downarrow\) [30, 38] & \(\downarrow\) [28, 38] & & \(\uparrow\) [28] \\   normal walking & & & & & \\   Walking when & & & & & \\   using a phone (gaming) vs. & \(\downarrow\) [37] & \(\downarrow\) [37] & \(\downarrow\) [37] & \(\downarrow\) [37] & \(\uparrow\) [37] \\   normal walking & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\ \hline  & & & & & \\ \end{tabular} \(\downarrow\), decreased; \(\uparrow\), increased.  
\end{table}
Table 2: The variables and main results of the included studies.  
questions. [PERSON] and [PERSON] et al. required subjects to answer daily life questions, such as questions about hobbies, by mobile phones while walking [17; 29]. High cognitive tasks involved solving some complex problems. In these tasks, participants were asked to type irregular words or answer professional questions [39]. The cognitive level could be important and might significantly affect dependent variables because cognitive load can affect general satisfaction and performance of subjects when completing complex tasks. However, no study has yet been conducted to examine the effects of tasks of different cognitive levels on gait. Therefore, the effects of tasks of different cognitive levels on gait should be studied in the future.