*2.1. Measurement System*

The measurement system used was the WaveTrack Inertial System (Cometa Systems, Italy; *https://www.cometasystems.com/*), which supported the four-sensor setting required for this study. The single device was a low weight (5.3 g), small-sized (32 mm × 24 mm × 7 mm), waterproof, inertial measurement unit (IMU; composed of a triaxial accelerometer, gyroscope, and magnetometer) with a wireless interface for real-time data streaming and a 1 GB of on-board memory, able to store up to 6 h of measurements. In the present study, only measurements of the triaxial accelerometer were considered; the sampling rate was 140 Hz with a 16-bit resolution analog-to-digital converter (ADC) and a full scale of ±16 g. Velcro elastic straps were provided for attaching sensors on selected anatomical landmarks.
