Related Experiment Video
Updated: May 22, 2026
07:53
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Cortical and Cortico-Muscular Network Modulation Pattern of Eccentric and Concentric Movements in Fatigue State
Summary
Fatigue alters brain-muscle communication differently for concentric and eccentric leg movements. Concentric tasks show more brain network compensation, while eccentric tasks enhance brain-muscle pathway strength and efficiency, offering insights for rehabilitation strategies.
Area of Science:
- Neuroscience
- Rehabilitation Science
- Biomedical Engineering
Background:
- Lower extremity motor deficits and fatigue commonly impair neurological injury recovery.
- Understanding how fatigue affects cortico-muscular networks during different movements is crucial for rehabilitation.
Purpose of the Study:
- To investigate the distinct modulations of inter-cortical and cortico-muscular networks during concentric and eccentric sit-to-stand tasks under fatigue.
- To compare network dynamics between pre-fatigue and post-fatigue states for different movement types.
Main Methods:
- Ten healthy subjects performed sit-to-stand tasks (concentric and eccentric) in pre-fatigue and post-fatigue states.
- Electroencephalogram (EEG) and electromyogram (EMG) signals were recorded, with fatigue confirmed by EMG mean power frequency (MPF) and EEG Lempel-Ziv complexity (LZC).
- Network analysis utilized generalized partial directed coherence (GPDC), clustering coefficient (CC), and global efficiency (GE) to assess inter-cortical and cortico-muscular connectivity.
Main Results:
- Concentric tasks (T1) showed increased inter-cortical connectivity post-fatigue and a shift from beta to gamma bands in cortico-muscular pathways.
- Eccentric tasks (T2) demonstrated increased CC and GE in the beta band, alongside upregulated descending and ascending cortico-muscular pathways in beta and gamma bands.
- Fatigue differentially impacted network connectivity and pathway strength between concentric and eccentric movements.
Conclusions:
- Concentric movements involve greater inter-cortical compensation and cortico-muscular band shifting under fatigue.
- Eccentric movements exhibit enhanced inter-cortical efficiency and stronger cortico-muscular network engagement when fatigued.
- Findings highlight distinct neural modulation patterns for concentric and eccentric movements, informing targeted rehabilitation program design.
Related Concept Videos
01:24Muscle Recovery and Fatigue
Muscle fatigue refers to the decline in a muscle's ability to maintain the force of contraction after prolonged activity. It primarily stems from changes within muscle fibers. Even before experiencing muscle fatigue, one may feel tired and have the urge to stop the activity. This response, known as central fatigue, occurs due to changes in the central nervous system, namely the brain and spinal cord. While there is no single mechanism that induces fatigue, it may serve as a protective response...
01:11Alterations in Muscle Tone lll
Rigidity and myotonia are distinct abnormalities of muscle tone that affect resistance and relaxation during movement. Although both involve altered muscle contraction, they arise from different neurological and muscular mechanisms.CharacteristicsRigidity is characterized by uniform resistance to passive movement across the entire range, independent of speed, affecting flexors and extensors equally. It may appear as lead-pipe rigidity (smooth, constant resistance) or cogwheel rigidity...
01:20Motor Unit Stimulation
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
01:12Alterations in Muscle Tone ll
Alterations in muscle tone are common manifestations of neurological disorders and reflect dysfunction within different nervous system regions. Spasticity, paratonia, and dystonia represent distinct forms of hypertonia, each with unique mechanisms, clinical features, and diagnostic importance.CharacteristicsSpasticity happens from upper motor neuron lesions and is characterized by velocity-dependent resistance to passive movement. Clinical features include:Exaggerated deep tendon reflexesClonus...
01:22Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:26Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.