Running or jogging is a popular form of physical activity all over the world. The advent of wearable technology is helping people perform this type of exercises by providing step count, monitoring heart rate, SpO2 etc. Runners, clinicians and coaches collect in-field data with wearable sensors to improve performance, avoid injury or return to running after an injury. However, it is yet to be proven that commercially available wearable sensors provide valid data.
Researchers from Interdisciplinary Research in Rehabilitation and Social Integration in Quebec City, and University of British Columbia, conducted a study to assess the concurrent validity of several popular, commercially available wearable sensors in estimating vertical ground reaction force (vertical loading rates) during running against a laboratory-based instrumented treadmill and motion capture system.
For their research, they used five wearable sensors (Moov Now, MilestonePod, RunScribe, TgForce and Zoi) to measure ground reaction force related metrics, step rate, foot strike pattern, and vertical displacement of the center of mass during running.
Researchers placed wearable sensors according to the manufacturers’ instructions and collected data with their dedicated commercial application (for TgForce, a beta Windows version software was used to collect data). Lab-based System Three-dimensional motion analysis was performed using a 9-camera VICON motion capture system and VICON Nexus software. Kinematic data were collected at 200 Hz. Rigid triads of non-colinear reflective markers were placed over the lumbosacral junction, and on the lateral part of the foot, shank and thigh, bilaterally. Triads attached to the thighs were made of custom-molded thermoplastic and were secured with Velcro straps to minimize movement artefacts.
The five sensors provided different metrics that were thought to represent vertical ground reaction forces. When compared to actual vertical loading rates, a gait parameter associated with running injury and running injury and running injury prevention, the correlations with these metrics ranged from none to high. This confirmed their hypothesis that only devices attached to the tibia (TgForce and Moov Now) showed significant correlations with lab-based vertical loading rates.
“In agreement with our hypothesis, healthcare professionals, coaches and runners can rely on step rate measurements provided by all wearable sensors tested in this study,” they wrote.
“Overall, runners, clinicians and coaches must keep in mind that only a limited number of the metrics provided by these commercially available wearable sensors are actually valid. Our results showed that step rate measurement is valid for all wearable sensors. TgForce was the only device providing valid metrics of instantaneous vertical loading rate. Only MilestonePod seemed to be valid to discriminate between a rear-, mid- and fore-foot strike pattern. Only Zoi was valid to estimate vertical displacement of the center of mass.”
The researchers involved the study were B. Pairot de Fontenay, J. S. Roy and L. Bouyer from the Centre for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec City; B. Dubois from The Running Clinic, Lac Beauport, Quebec; and J.F. Esculier from the Department of Physical Therapy, University of British Columbia, Vancouver.
The study was published in IEEE Sensors Journal.