Ultium emg

Muscle activity throughout the strength and fatigue tasks was recorded via a wireless EMG system (Ultium-EMG, Noraxon, USA Inc., Scottsdale, AZ, USA). EMG electrodes (3M Red Dot Monitoring Electrode, Model 2560; 3M Corp., St. Paul, MN, USA; 2 cm between each 1.3 cm effective area) were secured bilaterally over the rectus femoris, vastus medialis, vastus lateralis, and semitendinosus corresponding to a 3D muscle map which followed SENIAM guidelines, and was provided by the EMG software (MR 3.14, myoMUSCLE, Noraxon USA Inc., Scottsdale, AZ, USA). To increase electrode placement consistency, the same researchers placed the electrodes on the subjects during each visit. The electrode sites were prepared by shaving and cleaning the electrode site with an alcohol wipe before placing the electrodes. The electrodes and wireless transmitters were secured in place with elastic bandages and EMG data were collected at 2000 Hz.

InvenSense MEMS sensors with integrated IMUs (MPU9250) from Noraxon (Ultium EMG, Noraxon, Scottsdale, AZ, USA) were used to measure the angular velocity ( $\pm 2000$ degrees/s), acceleration ( $\pm 16$ g), and magnetic field amplitude ( $\pm 4800$ µT). The sampling rate was set to $400\mathrm{Hz}$ . An OMC system comprising 27 infrared cameras set to a sampling rate of $200\mathrm{Hz}$ (Vicon, Bilston, UK) was used as a reference tool. A total of 42 retro-reflective spherical markers ( $14\mathrm{m}\mathrm{m}$ ) were placed on bony landmarks according to the plug-in gait model [20 (link)].

Surface electromyography (EMG) signals were recorded using Ultium EMG (Noraxon USA Inc., Scottsdale, AZ, USA) for gluteus maximus, gluteus medius, rectus femoris, biceps femoris, tibialis anterior, medial gastrocnemius, and soleus on the left leg throughout the study. The attachment sites of the electrode on the skin were shaved and cleaned with alcohol. Disposable self‐adhesive Ag/AgCl surface electrodes were then attached at locations 2 cm apart over each muscle belly and parallel to the orientation of the muscle fibers. The EMG signals were processed and analyzed with MR 3.18 software (Noraxon Inc). Raw EMG was collected at 2000 Hz and band‐pass filtered (Lancosh FIR) between 10 and 500 Hz. The EMG data were rectified and further smoothed using the root mean square with a moving window of 50 ms. During the intervention, the 20‐min period was divided into four stages, and 60 s of raw EMG data were selected for analysis in each stage. Each peak of EMG activity represented the activation of the corresponding muscle during a leg shaking cycle. A total of n = 14 EMG measurements were made as an equipment malfunction voided one subject's dataset.