Gait event detection using hybrid EMG/IMU systems: effect of SENIAM-constrained sensor placement on lower limb...

Inertial Measurement Units (IMUs) are well-established tools for measuring motion and have recently been integrated into electromyographic (EMG) sensor enabling simultaneous acquisition of motion and muscular activity. However, their reliability and validity remain inconsistent, and standardized sensor placement has yet to be established. IMU positioning, especially on the lower limb, significantly impacts movement quantification, complicating clinical interpretation. This study evaluates how hybrid IMU/EMG sensor placement affects gait event detection and temporal parameters whether or not SENIAM (Surface ElectroMyoGraphy for the Non-Invasive Assessment of Muscles) placement guidelines are followed . Specifically, it examines detection rates by sensor location, gait event accuracy, and the influence of placement on temporal parameter. The hypothesis favors shank and non-SENIAM locations for accuracy. Thirty participants, including healthy individuals, lower-limb amputees, and post-surgical patients wore seven DELSYS Avanti® sensors: four hybrid IMU/EMG were placed following SENIAM guidelines, and three IMU-only sensors on the thigh, tibia, and foot. Data were collected during a 3-minute walk evaluation indoors and outdoors. Shank sensors detected more than 99% of all gait events; thigh sensors, especially the gluteus medius, performed poorly. Shank sensors were more precise for initial/terminal contact events, with minimal errors between SENIAM and non-SENIAM placements. Cadence remained stable across locations, except for a slight effect of SENIAM placement on the thigh. Sensor placement substantiallyaffects gait event detection. Shank positioning outperforms thigh placement, likely due to reduced artifacts. SENIAM placement had little impact, but gluteus medius positioning proved unreliable. Standardized protocols are essential for consistent clinical gait analysis.