Keywords Ground reaction force, total force, force plate, gait analysis
Study Design: Descriptive Study
Background: Both clinicians and researchers often utilize treadmills to analyze spatiotemporal and biomechanical factors during running. However, there is question of whether or not treadmill running mimics overground running. The development of new wearable technology, such as pressure sensor insoles, presents
an opportunity to compare the two running conditions.
Purpose: To determine the validity of Moticon’s SCIENCE Sensor Insole (model: insole3) force output and its force zero level behavior during walking at normal speed. The study
quantifies the error of total force measurements compared to the output of force plates.
Methods: Ten healthy subjects (age 33.4, SD=7.68, 30% female) carried out trials to capture multiple left stance periods and the subsequent right stance periods during a longer walking sequence. The setup comprises a chair and two Hawkin Dynamics force plates (Hawkin Dynamics LLC, Westbrook, USA) which are placed in a bilateral configuration. Six runs were carried out with each subject, each 3 runs without specific calibration and 3 runs with the standard total force calibration routine included in the Moticon SCIENCE Mobile App. Zero levels of the pressure sensors were analyzed during the walking as of after a 2-minute warm up period in sitting.
Results: Compared to the force plate readings, insole3 force data of overground walking deviated 3.51% regarding average peak error (SD=4.78%) and 0.62% regarding average NMAE (normalized mean absolute error, SD=3.27%) using the standard calibration routine. No single peak error deviated more than 10.4% from the force plate reading. No NMAE error deviated more than 2.66% from the force plate reading. An average peak error of 20.2% (SD=6.11%) and a NMAE of 7.48% (SD=3.14%) was observed in the runs without the standard calibration routine. The zero levels resulted in an overall average of 5.8N for the uncalibrated runs and 6.4N for the calibrated runs.
Levels of Evidence: Inhouse study