mHealth Research Digest with Tim Bredrup

Smartphones are becoming more ubiquitous and many have a built in tri-axial accelerometer, a sensor that measures change in speed in multiple directions. These smartphone accelerometers can be used to assess gait patterns, or walking patterns, an important evaluation in many neurologic or musculoskeletal disorders. However, the reliability and validity of using smartphones to assess gait patterns is not yet fully established evaluated. In Japan, a team of registered physical therapists and other physicians performed a study to do just that.

A total of 30 healthy young adults were studied, all of whom were , walked 20 meters (~65 ft.) at their normal preferred pace. While walking, their trunk accelerations were measured simultaneously by an Android smartphone and a standard tri-axial accelerometer that was secured to a place on their lower back, near the L3 spinour process. The research team developed a gait analysis app and installed it on the smartphone. After signal processing, the gait parameters of each measurement terminal were calculated. The main parameter evaluated was the acceleration peak intervals, including related statistics such as peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV).

The researchers found high correlation between standard accelerometers and the smartphone, with values of  PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; (p<0.01) and stated.

“Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone … 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.”

The team concluded that the Android smartphone, equipped with the gait analysis application, is indeed capable of quantifying gait parameters with a similar degree of accuracy to the tri-axial accelerometer.

Authors: Nishiguchi S, Yamada M, Nagai K, Mori S, Kajiwara Y, Sonoda T, Yoshimura K, Yoshitomi H, Ito H, Okamoto K, Ito T, Muto S, Ishihara T, Aoyama T

Institution: Department of Physical Therapy, Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan

Original Abstract: PubMed