reliability and validity study of pacer smartphone application to count steps in overweight and obese young adults

Abstract Background: While pedometer smartphone applications are popular, evidence of their ability to monitor accurately physical activity is still missing, especially in obese individuals. The objective of this study was to determine the reliability and validity of PACER smartphone application in free-living and controlled conditions to count steps, in overweight or obese young adults. Methodology: 30 overweight or obese participants (50% males, mean age, 21.37±0.20 y) were recruited from a major university in the United Arab Emirates. They carried a smartphone with PACER application in their right pocket, and an OMRON HJ-320E pedometer on the right hip, for seven consecutive days, in free-living conditions. Participants were also recorded while walking for 30 minutes on a treadmill, at a speed of 3km/h with their smartphone and OMRON pedometer. Each experiment was repeated twice. Results: In free-living conditions, reliability was fair to excellent (Intraclass Correlation Coefficients (ICC) from 0.43 to 0.77) while in controlled conditions it was less than poor in male (ICC=0.20), fair-to-good in female (ICC=0.55) and the whole group (ICC=0.42). Significant correlations (rho=0.64 in female, p≤0.01, and 0.94 in male, p≤0.001) were obtained in free-living conditions, between PACER and OMRON. Under controlled conditions, significant correlations were observed between PACER and the manual counting, but not OMRON, and in the whole sample and females, only (rho=0.48, p=0.01 and rho=0.72, p≤0.001, respectively). Conclusion: PACER smartphone application is a fairly reliable and valid tool to count steps in free-living and controlled conditions in overweight and obese young adults. Keywords Obesity; PACER; Reliability; Smartphone application; Validity; Young adults