Abstract
Coordination of functionally coupled muscles is a key aspect of movement execution. Demands on coordinative control increase with the number of involved muscles and joints, as well as with differing movement periods within a given motor sequence. While previous research has provided evidence concerning inter- and intramuscular synchrony in isolated movements, compound movements remain largely unexplored. With this study, we aimed to uncover neural mechanisms of bilateral coordination through intermuscular coherence (IMC) analyses between principal homologous muscles during bipedal squatting (BpS) at multiple frequency bands (alpha, beta, and gamma). For this purpose, participants performed bipedal squats without additional load, which were divided into three distinct movement periods (eccentric, isometric, and concentric). Surface electromyography (EMG) was recorded from four homologous muscle pairs representing prime movers during bipedal squatting. We provide novel evidence that IMC magnitudes differ between movement periods in beta and gamma bands, as well as between homologous muscle pairs across all frequency bands. IMC was greater in the muscle pairs involved in postural and bipedal stability compared with those involved in muscular force during BpS. Furthermore, beta and gamma IMC magnitudes were highest during eccentric movement periods, whereas we did not find movement-related modulations for alpha IMC magnitudes. This finding thus indicates increased integration of afferent information during eccentric movement periods. Collectively, our results shed light on intermuscular synchronization during bipedal squatting, as we provide evidence that central nervous processing of bilateral intermuscular functioning is achieved through task-dependent modulations of common neural input to homologous muscles.NEW & NOTEWORTHY It is largely unexplored how the central nervous system achieves coordination of homologous muscles of the upper and lower body within a compound whole body movement, and to what extent this neural drive is modulated between different movement periods and muscles. Using intermuscular coherence analysis, we show that homologous muscle functions are mediated through common oscillatory input that extends over alpha, beta, and gamma frequencies with different synchronization patterns at different movement periods.
Highlights
Everyday life activities comprise isolated movements and compound whole body movements such as walking, climbing stairs, and standing (Casale et al 2011)
We provide novel evidence that, during bipedal squat (BpS), homologous muscle functions are mediated through common oscillatory inputs spanning across alpha, beta, and gamma frequencies with distinct synchronization patterns at different movement periods
We show that for beta and gamma intermuscular coherence (IMC) the magnitude of common input is greater in dynamic movement periods (ECC and CON) when compared with static periods (ISO)
Summary
Everyday life activities comprise isolated movements and compound whole body movements such as walking, climbing stairs, and standing (Casale et al 2011). Whole body movements require extensive control of many muscle groups of the upper and lower extremities. IMC is associated with cortical and spinal mechanisms (Boonstra 2013; Boonstra and Breakspear 2012; Grosse and Brown 2003) and was previously used to demonstrate functional binding between muscles (Laine and Valero-Cuevas 2017). Synchronized oscillations at alpha frequencies are present during the activity of different muscles during uniand bimanual motor control tasks of upper (de Vries et al 2016; McAuley et al 1997) and lower extremities (Boonstra et al 2008, 2015). Beta band oscillations have been observed in functionally related muscles (Boonstra 2013; Boonstra and Breakspear 2012; Kilner et al 1999) and were originally thought to reflect efferent origin (Brown et al 1999), www.jn.org
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
