# The Impact of Cell Phone Usage on Fall Risk and Postural Control During Free-Standing
## 1 Introduction
Research indicates that performing dual tasks, such as using a smartphone while walking, can negatively affect dynamics [13]. Contemporary research on postural control increasingly highlights the impact of technology, particularly mobile phones, on body stability [14]. Smartphone use during movement, such as walking, reduces lower limb stability, restricts arm motion, and shifts focus toward phone interactions at the expense of balance [15]. Mobile phone use in daily activities increases cognitive load, visual distraction, and manual demands, which collectively elevate the risk of falls, one of the leading causes of unintentional injury among young adults [13; 16]. Additionally, smartphone use is a dual-task activity that divides attention and negatively affects postural stability and motor coordination [17; 18]. A particularly important factor is the alignment of the head and neck while using a phone. Smartphone users often hold devices below eye level, leading to forward head tilt, cervical flexion, and compensatory curvature of the upper thorax. This disrupts the biomechanical balance of the cervical spine [14; 19]. Research shows that, while standing, the C0-C1 joint (at the skull base) experiences significant flexion of approximately 27.50 \(\pm\) 14.05\({}^{\circ}\), while the lower cervical vertebrae (C2-C7) remain almost immobile [20]. Phone use typically results in a head tilt of 30-35 degrees, increasing cervical spine strain. At 30 degrees, the head's effective weight increases from 5 kg in a neutral position to 18 kg; at 45 degrees, it rises to 22 kg, and at 60 degrees, it reaches 27 kg [20; 21]. Prolonged strain can lead to neck pain,poor posture, and permanent spinal changes, emphasizing the need for the awareness of ergonomic posture during phone use [22; 23]. In addition to head and neck positioning, the way a phone is held also influences postural control and body stability. Using a phone often requires the involvement of one or both hands, which can significantly affect balance. Holding the phone with one hand is usually associated with asymmetric weight distribution and limited compensatory arm movement, leading to increased instability in the lateral plane. While static conditions allow users to maintain a relatively stable posture, even holding a phone in one hand can introduce slight imbalances. Texting with both hands, on the other hand, requires greater upper limb involvement, altering the body's center of gravity and restricting free balancing movements. Furthermore, using both hands leads to a higher degree of visual fixation on the screen, reducing environmental awareness and the ability to react quickly to changes in balance conditions [24; 25]. Together, these factors underscore the importance of informed smartphone use to mitigate its impact on postural stability and musculoskeletal health. The aim of this study was to assess the impact of smartphone usage (both holding and texting) on fall risk and postural control in healthy young adults. The following hypothesis was formulated: mobile phone use during standing impairs postural control by increasing CoP variability, reducing adaptive control (SampEn), and decreasing postural complexity (FD, LyE), thereby increasing the risk of falls.