Investigation of the validity and reliability of a smartphone pedometer application

The aim of this study was to investigate the validity and measurement agreement of a smartphone pedometer application and a traditional pedometer, both compared to manual step count, in six environments. The study also examined the relative reliability of two positions of the smartphone pedometer application in the six environments. Twenty participants carried two smartphones (iPhone 4S) with the same pedometer application (Pedometer FREE GPS+) in two device positions together with a traditional pedometer (Yamax LS2000) while walking in six environments. The pedometer application in the chest position (app chest) differed significantly from the manual step count when walking uphill (p = 0.003), the application in the trouser (pants) position (app pants) differed for downhill (p = 0.001) and the traditional pedometer (trad ped) differed upstairs (p = 0.007). The measurement agreement was high for app pants uphill, app chest downhill and trad ped downstairs. The relative reliability was fair for app chest, but poor for app pants. In conclusion, the pedometer application and traditional pedometer were valid for step self-monitoring in some environments, and the measurement agreement compared to manual step count was mainly medium to high. The relative reliability for the smartphone pedometer application was partly acceptable. Smartphones could be useful in some environments for physical activity self-monitoring.