# The Impact of Cell Phone Usage on Fall Risk and Postural Control During Free-Standing
## 4 Discussion  
This study examined the impact of smartphone use, including passive phone holding and active texting, on postural control and fall risk in healthy young adults. Notably, the experiments were conducted on both a dynamic balance platform, simulating less controlled environments like bus riding, and a static platform, representing a stable and safe environment. The hypothesis, which suggested that mobile phone usage would impair postural control and increase the risk of falls, was supported by the findings. The linear measures, including CoP path length, revealed a significant increase in the AP direction under both passive phone holding and texting conditions. Specifically, the CoP path length was significantly longer in the AP direction for the EP and SMS trials compared to the baseline EO trial. This suggests that holding a phone, especially while texting, leads to a more pronounced shift in the body's center of pressure, potentially indicating compromised postural stability. The dynamic nature of texting, which requires additional motor and cognitive processing, may explain these alterations in postural control [32,33]. Interestingly, while the total CoP path length did not differ significantly across the three trials, differences in the CoP path length in the ML and AP directions were notable. This implies that the directionality of balance control is more affected by phone usage during standing. The increase in CoP path length in the AP direction aligns with the requirement for more forward and backward postural adjustments when the user is distracted by a mobile device [20]. The FRTi also showed significant differences between trials, with the highest values recorded during the texting trial. These findings are in agreement with the notion that multitasking, especially cognitive-motor tasks such as texting, is linked to increased fall risk. The substantial increase in FRTi during the SMS trial indicates that the dual-tasking required in this condition may significantly impair postural control. These results underscore the risks of performing tasks that demand cognitive attention while standing, as it compromises the individual's ability to maintain postural stability. This aligns with the findings of [PERSON] et al. [34]. This study reinforces previous research indicating that smartphone use negatively impacts postural control, particularly during dual-task activities. Specifically, the observed increase in CoP variability, especially in the AP direction during phone use, aligns with [PERSON] and [PERSON]'s [4] assertion that nonlinear measures are critical in evaluatingbalance. Increased CoP variability indicates decreased efficiency in the adaptive mechanisms required to maintain stability. The cognitive-motor dual task of texting significantly reduced SampEn values, signaling diminished adaptive control. [PERSON] [5] obtained similar results, showing that cognitive distractions, such as texting, interfere with the automatization of postural control. Additionally, the reduced LyE values during texting suggest limited adaptability to environmental changes. This supports [PERSON]'s [7] findings on how task complexity and age can influence CoP signals. Although there were no significant changes in FD, indicating that postural complexity was not entirely compromised, the reduced SampEn and LyE values suggest an increase in postural rigidity. This rigidity was further reflected in the high FRTi observed during texting trials, which parallels [PERSON] and [PERSON]'s [16] findings linking mobile phone use to an increased incidence of falls. Nonlinear measures of postural control, such as SampEn and LyE, also revealed substantial differences between the trials. SampEn, a measure of postural complexity, showed reduced values during the EP and SMS trials, particularly in the AP direction. This reduction suggests that mobile phone use, especially while texting, diminishes postural control complexity, making it more predictable and less adaptable.