Novel algorithm for a smartphone-based 6-minute walk test application: algorithm,application development,and evaluation

Background: the 6-minute walk test (6mwt: the maximum distance walked in 6 minutes) is used by rehabilitation professionals as a measure of exercise capacity. today's smartphones contain hardware that can be used for wearable sensor applications and mobile data analysis. a smartphone application can run the 6mwt and provide typically unavailable biomechanical information about how the person moves during the test.methods: a new algorithm for a calibration-free 6mwt smartphone application was developed that uses the test's inherent conditions and smartphone accelerometer-gyroscope data to report the total distance walked,step timing,gait symmetry,and walking changes over time. this information is not available with a standard 6mwt and could help with clinical decision-making. the 6mwt application was evaluated with 15 able-bodied participants. a blackberry z10 smartphone was worn on a belt at the mid lower back. audio from the phone instructed the person to start and stop walking. digital video was independently recorded during the trial as a gold-standard comparator.results: the average difference between smartphone and gold standard foot strike timing was 0.014 ± 0.015 s. the total distance calculated by the application was within 1 m of the measured distance for all but one participant,which was more accurate than other smartphone-based studies.conclusions: these results demonstrated that clinically relevant 6mwt results can be achieved with typical smartphone hardware and a novel algorithm.