Department of Physical Therapy, Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Telemed J E Health. 2012 May;18(4):292-6. doi: 10.1089/tmj.2011.0132. Epub 2012 Mar 8.
Smartphones are very common devices in daily life that have a built-in tri-axial accelerometer. Similar to previously developed accelerometers, smartphones can be used to assess gait patterns. However, few gait analyses have been performed using smartphones, and their reliability and validity have not been evaluated yet. The purpose of this study was to evaluate the reliability and validity of a smartphone accelerometer. Thirty healthy young adults participated in this study. They walked 20 m at their preferred speeds, and their trunk accelerations were measured using a smartphone and a tri-axial accelerometer that was secured over the L3 spinous process. We developed a gait analysis application and installed it in the smartphone to measure the acceleration. After signal processing, we calculated the gait parameters of each measurement terminal: peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone (p<0.001). All the gait parameter results obtained by the smartphone showed statistically significant and considerable correlations with the same parameter results obtained by the tri-axial accelerometer (PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; p<0.01). Our study indicates that the smartphone with gait analysis application used in this study has the capacity to quantify gait parameters with a degree of accuracy that is comparable to that of the tri-axial accelerometer.
智能手机在日常生活中非常常见，内置三轴加速度计。与以前开发的加速度计类似，智能手机可用于评估步态模式。但是，使用智能手机进行的步态分析很少，其可靠性和有效性尚未得到评估。本研究旨在评估智能手机加速度计的可靠性和有效性。 30 名健康的年轻成年人参加了这项研究。他们以自己喜欢的速度走 20 米，并用智能手机和固定在 L3 棘突上的三轴加速度计测量其躯干加速度。我们开发了一个步态分析应用程序并将其安装在智能手机中以测量加速度。经过信号处理，我们计算了每个测量终端的步态参数：峰值频率（PF）、均方根（RMS）、自相关峰值（AC）和加速度峰值间隔的变异系数（CV）。智能手机获得的所有步态参数结果的测试-重测可靠性都非常一致（p<0.001）。智能手机获得的所有步态参数结果与三轴加速度计获得的相同参数结果均显示出统计学显著且相当大的相关性（PF r=0.99，RMS r=0.89，AC r=0.85，CV r=0.82；p<0.01）。我们的研究表明，本研究中使用的具有步态分析应用程序的智能手机具有以可与三轴加速度计相媲美的精度量化步态参数的能力。
