Meg 6108

Electromyographic (EMG) activity was recorded from the ES muscle unilaterally. Bipolar Ag/AgCl surface electrodes (Vitrode F-150S, Nihon Koden, Tokyo, Japan) were placed, with 1 cm separation, on the left ES muscle on the 12th thoracic vertebral level, 3 cm left side of the spinous processes (Sasaki et al. 2020 (link)) (Fig. 1B). A ground electrode was placed over the right anterior superior iliac spine. Prior to the application of electrodes, the skin was cleaned using alcohol swabs to reduce skin impedance. Signals were band-pass filtered (5–1000 Hz) and amplified (× 1000) using a multi-channel EMG amplifier (MEG-6108, Nihon Kohden, Tokyo, Japan). All data were digitized at a sampling frequency of 4000 Hz using an analog-to-digital converter (PowerLab/16SP, AD Instruments, Castle Hill, Australia) and stored on a computer for post-processing.

Electromyographic (EMG) activity was recorded unilaterally from the right (dominant in all the subjects) hand: (1) biceps brachii (BB), (2) triceps brachii (TB), (3) flexor carpi radialis (FCR), (4) extensor carpi radialis (ECR), (5) first dorsal interosseous (FDI), and (6) abductor pollicis brevis (APB) muscles. Surface EMG electrodes (Ag/AgCl; Vitrode F-150S; Nihon Kohden, Tokyo, Japan) were placed on the muscle belly of the right upper limb with an approximate interelectrode distance of 20 mm, whereas APB electrodes were placed over the muscle belly and first metacarpophalangeal joint, and FDI electrodes were placed over the muscle belly and the second metacarpophalangeal joint [23 (link)]. A reference electrode was placed around the lateral epicondyle. Prior to application of electrodes, skin was cleaned using alcohol swabs to reduce skin impedance. Signals were band-pass filtered (5–1000 Hz) and amplified (×1000) using a multi-channel EMG amplifier (MEG-6108, Nihon Kohden, Tokyo, Japan). All data were digitized at a sampling frequency of 4000 Hz using an analog-to-digital converter (PowerLab/16SP, AD Instruments, Castle Hill, Australia) and stored on a computer for post processing.

Electromyographic (EMG) activity was recorded from the FCR, extensor carpi radialis (ECR), rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and SOL on the right side. EMG signals were obtained with surface electrodes (SS-2096, Nihon Kohden, Tokyo, Japan) placed over the muscle belly after decreasing impedance of skin to below 10 kΩ by light abrasion and cleaning with alcohol. All EMG signals were amplified (1000×) and band-pass filtered between 15 Hz and 3 kHz via a bioelectrical signal amplifier system (MEG-6108, Nihon Kohden, Tokyo, Japan; Nakajima et al., 2011 (link)). All data signals were converted to digital data with an analog-to-digital converter system (Micro 1401, CED Co. LTD., UK) and recorded on a hard disk of personal computer with a sample rate of 5 kHz using Spike 2^® software (CED Co. LTD., UK; Nakajima et al., 2011 (link)).

Surface electromyography (EMG) was performed on the right SOL muscle using surface Ag/AgCl electrodes (Vitrode F-150-S, Nihon Kohden, Japan). EMG signals were pre-amplified 1000-fold and filtered with a bandpass filter of 5–1000 Hz (MEG-6108, Nihon Kohden, Japan). All EMG signals were digitized at 4000 Hz using an analog-to-digital converter (Power lab/16SP, AD Instruments, Australia) and stored on a computer for offline analysis.

Surface EMG activities were recorded from the bilateral TA and SOL muscles. Standard skin preparations using alcohol and tape for abrasion were applied before the attachment of disposable electrodes (diameter: 7 mm). Bipolar Ag/AgCl surface electrodes were placed on the muscle belly with an inter-electrode distance of 10 mm. The electrodes for the TA were attached longitudinally at the one third of the distance between the tibial tuberosity and center of ankle joint and 1cm lateral edge of the tibia. Those of SOL was placed 2cm medial from the Achilles tendon and 1cm below the lower edge of medial gastrocnemius belly. Thin elastic bandages were wrapped to hold electrodes stably on the muscles and lead lines as well. EMG signals were amplified ×1000 using a bioelectric amplifier (MEG-6108, Nihon Kohden, Japan) with a bandpass filter (15–1000 Hz) and digitized at a sampling rate of 2 kHz. The signals were recorded for 500 ms before and after perturbations.

EMG activities were recorded unilaterally from right side of: (1) ES muscle on the 12th thoracic vertebral level (ES; trunk extensor muscle); (2) RA muscle lateral to the umbilicus (RA; trunk flexor muscle); and (3) tibialis anterior muscle lateral to the tibia (TA; lower-limb muscle). Two bipolar Ag/AgCl surface electrodes (Vitrode F-150S, Nihon Kohden) were placed over the muscle belly with 1 cm separation. A ground electrode was placed over the right anterior superior iliac spine. Before application of electrodes, skin was cleaned using alcohol to reduce impedance. All EMG signals were bandpass filtered (5–1000 Hz) and amplified (1000×) using a multichannel amplifier (MEG-6108, Nihon Kohden). All data were digitized at a sampling frequency of 4000 Hz using an analog-to-digital (A/D) converter (Powerlab/16SP, AD Instruments) and stored on the computer for postprocessing.