Google fit smartphone application or Gt3X Actigraph: Which is better for detecting the stepping activity of individuals with stroke? A validity study

Objective: To examine the validity of the GT3X (R) ActiGraph accelerometer and the Google Fit (R) smart-phone application in estimating stepping activity in people with chronic stroke. Methods: Thirty-seven stroke survivors walked along a straight, 10 metre hallway over 5 min at their fastest speeds, wearing the GT3X (R) ActiGraph accelerometer and a smartphone on their paretic lower limb. The criterion-standard measurement made was the actual number of steps, counted by a trained examiner. Results: The mean estimated steps measured by the GT3X (R) ActiGraph and Google Fit (R) respectively were 276.7 +/- 97.6 and 481.0 +/- 119.8; that calculated from the examiner's measurements was 472.0 +/- 93.9. Statistically significant associations were found between the actual steps and those estimated by the GT3X (R) ActiGraph (r = 0.56; p <0.001) and Google Fit (R) (r = 0.89; p <0.001). The Google Fit (R) application demonstrated the highest reliability coefficient (ICC[2,1] = 0.93; p < 0.001; p = 0.37), compared to that of the GT3X (R) ActiGraph (ICC[2,1] = 0.32; p < 0.001; p < 0.001). Conclusions: The GT3X (R) ActiGraph underestimated the data and may not be the most appropriate device to estimate the stepping activity of stroke patients. The findings support the validity of a smartphone application in estimating the stepping activity of individuals with stroke, when worn on the paretic side. (C) 2019 Elsevier Ltd. All rights reserved.