# Smartphone Accelerometer for Gait Assessment: Validity and Reliability in Healthy Adults
## 3 Results  
### General Characteristics of Participants  
All participants in this study successfully completed the measurements without any dropouts. The characteristics of the 30 subjects are as follows (Table 1). Figure 3: Calculation process. Correlation Between Gait Analysis Results Using Smartphone Acceleration System and GAITRite Gait Analysis Results  
There was no significant difference in the average of the values measured four times for each condition among the gait variables measured by smartphone and GAITRite, respectively (\(p\) > 0.05). The degree of correlation between the two systems is expressed in Table 2. When the intraclass correlation analysis was applied to the average data measured by the two systems, the ICC of Distance, Ambulation Time, Velocity, Mean Normalized Velocity, and Cadence at preferred walking speed was 0.877-0.999, at fast walking speed, it was 0.810-0.995, and at slow walking speed, it was 0.778-0.999, showing a high (Good) level (\(p\) < 0.001). Consistency Between the Results of Gait Analysis Using the Smartphone Acceleration System and the Results of GAITRite Gait Analysis  
The Bland-Altman analysis, which compared two measurement systems across various gait parameters at preferred, fast, and slow walking speeds, revealed differences between the systems (Table 3) (Figure 4). For walking distance, the mean differences ranged from 4.79 cm to 9.53 cm across the different speeds. Ambulation time differences were minimal, with mean differences of up to 0.02 s and limits of agreement (LOA) within 0.09 s. \begin{table}
\begin{tabular}{c c} \hline
**Variables** & **Value** \\ \hline Age (y) 1  & 22.43 \(\pm\) 3.25 \\ Sex (M/F) 2  & 14/16 \\ Height (cm) 3  & 166.60 \(\pm\) 9.07 \\ Weight (kg) 4  & 61.96 \(\pm\) 14.09 \\ BMI (kg/m2) 5  & 22.09 \(\pm\) 3.45 \\ Leg Length (cm)—Left side & 86.70 \(\pm\) 4.60 \\ —Right side & 86.76 \(\pm\) 4.61 \\ \hline \end{tabular}
\end{table} 
Table 1: General characteristics. \begin{table}
\begin{tabular}{l c c c c c} \hline
**Variables** & **Smartphone Accelerometer** & **GAITRite** & & & & \\
**(Mean \(\pm\) SD)** & **(Mean \(\pm\) SD)** & **ICC** & **95\% CI** & \(p\)**-Value** \\ \hline Distance (cm) & & & & & \\ Preferred & 267.75 \(\pm\) 28.43 & 258.22 \(\pm\) 24.71 & 0.877 & 0.659–0.948 & \textless{}0.001 \\ Fast & 264.85 \(\pm\) 23.40 & 256.93 \(\pm\) 16.07 & 0.810 & 0.547–0.915 & \textless{}0.001 \\ Slow & 273.55 \(\pm\) 21.43 & 268.76 \(\pm\) 18.79 & 0.778 & 0.540–0.894 & \textless{}0.001 \\ \hline Ambulation Time (s) & & & & & \\ Preferred & 2.10 \(\pm\) 0.37 & 2.10 \(\pm\) 0.37 & 0.999 & 0.998–0.999 & \textless{}0.001 \\ Fast & 1.69 \(\pm\) 0.29 & 1.67 \(\pm\) 0.30 & 0.995 & 0.987–0.998 & \textless{}0.001 \\ Slow & 2.77 \(\pm\) 0.51 & 2.75 \(\pm\) 0.52 & 0.999 & 0.997–0.999 & \textless{}0.001 \\ \hline Velocity (cm/s) & & & & & \\ Preferred & 129.62 \(\pm\) 15.57 & 125.28 \(\pm\) 14.57 & 0.921 & 0.772–0.967 & \textless{}0.001 \\ Fast & 159.74 \(\pm\) 20.29 & 158.07 \(\pm\) 23.11 & 0.948 & 0.891–0.975 & \textless{}0.001 \\ Slow & 101.25 \(\pm\) 13.94 & 100.12 \(\pm\) 13.13 & 0.938 & 0.870–0.970 & \textless{}0.001 \\ \hline Mean Normalized Velocity (LL/s) & & & & & \\ Preferred & 1.49 \(\pm\) 0.14 & 1.44 \(\pm\) 0.14 & 0.880 & 0.651–0.951 & \textless{}0.001 \\ Fast & 1.81 \(\pm\) 0.20 & 1.79 \(\pm\) 0.23 & 0.939 & 0.874–0.971 & \textless{}0.001 \\ Slow & 1.17 \(\pm\) 0.13 & 1.15 \(\pm\) 0.13 & 0.911 & 0.815–0.958 & \textless{}0.001 \\ \hline Cadence (steps/min) & & & & & \\ Preferred & 115.76 \(\pm\) 7.27 & 115.93 \(\pm\) 7.36 & 0.989 & 0.978–0.995 & \textless{}0.001 \\ Fast & 130.03 \(\pm\) 10.6 & 130.76 \(\pm\) 10.66 & 0.993 & 0.984–0.997 & \textless{}0.001 \\ Slow & 102.16 \(\pm\) 8.31 & 102.79 \(\pm\) 8.55 & 0.990 & 0.977–0.995 & \textless{}0.001 \\ \hline \end{tabular}
\end{table} 
Table 2: Correlation of gait analysis using smartphone accelerometer system and GAITRite system. For walking velocity, the mean differences ranged from 1.13 cm/s to 4.34 cm/s, while normalized velocity showed mean differences between 0.01 LL/s and 0.05 LL/s.