TY - JOUR
T1 - Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking
AU - Kerkman, Jennifer N.
AU - Bekius, Annike
AU - Boonstra, Tjeerd W.
AU - Daffertshofer, Andreas
AU - Dominici, Nadia
PY - 2020/7
Y1 - 2020/7
N2 - When walking speed is increased, the frequency ratio between the arm and leg swing switches spontaneously from 2:1 to 1:1. We examined whether these switches are accompanied by changes in functional connectivity between multiple muscles. Subjects walked on a treadmill with their arms swinging along their body while kinematics and surface electromyography (EMG) of 26 bilateral muscles across the body were recorded. Walking speed was varied from very slow to normal. We decomposed EMG envelopes and intermuscular coherence spectra using non-negative matrix factorization (NMF), and the resulting modes were combined into multiplex networks and analyzed for their community structure. We found five relevant muscle synergies that significantly differed in activation patterns between 1:1 and 2:1 arm-leg coordination and the transition period between them. The corresponding multiplex network contained a single module indicating pronounced muscle co-activation patterns across the whole body during a gait cycle. NMF of the coherence spectra distinguished three EMG frequency bands: 4–8, 8–22, and 22–60 Hz. The community structure of the multiplex network revealed four modules, which clustered functional and anatomical linked muscles across modes of coordination. Intermuscular coherence at 4–22 Hz between upper and lower body and within the legs was particularly pronounced for 1:1 arm-leg coordination and was diminished when switching between modes of coordination. These findings suggest that the stability of arm-leg coordination is associated with modulations in long-distant neuromuscular connectivity.
AB - When walking speed is increased, the frequency ratio between the arm and leg swing switches spontaneously from 2:1 to 1:1. We examined whether these switches are accompanied by changes in functional connectivity between multiple muscles. Subjects walked on a treadmill with their arms swinging along their body while kinematics and surface electromyography (EMG) of 26 bilateral muscles across the body were recorded. Walking speed was varied from very slow to normal. We decomposed EMG envelopes and intermuscular coherence spectra using non-negative matrix factorization (NMF), and the resulting modes were combined into multiplex networks and analyzed for their community structure. We found five relevant muscle synergies that significantly differed in activation patterns between 1:1 and 2:1 arm-leg coordination and the transition period between them. The corresponding multiplex network contained a single module indicating pronounced muscle co-activation patterns across the whole body during a gait cycle. NMF of the coherence spectra distinguished three EMG frequency bands: 4–8, 8–22, and 22–60 Hz. The community structure of the multiplex network revealed four modules, which clustered functional and anatomical linked muscles across modes of coordination. Intermuscular coherence at 4–22 Hz between upper and lower body and within the legs was particularly pronounced for 1:1 arm-leg coordination and was diminished when switching between modes of coordination. These findings suggest that the stability of arm-leg coordination is associated with modulations in long-distant neuromuscular connectivity.
KW - electromyography
KW - interlimb coordination
KW - locomotion
KW - muscle networks
KW - muscle synergies
UR - http://www.scopus.com/inward/record.url?scp=85089339697&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85089339697&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/777a5e17-c6ad-3ea2-a774-eb5781d7ea33/
U2 - 10.3389/fphys.2020.00751
DO - 10.3389/fphys.2020.00751
M3 - Article
VL - 11
SP - 1
EP - 13
JO - Frontiers in Physiology
JF - Frontiers in Physiology
SN - 1664-042X
IS - July
M1 - 751
ER -