摩托单元招募值的调节和三肌中共同的突触输入:脚位置的影响
Xin Sienna Yu1,2, Jackson T Levine1,3, José L Pons1,2,3
1Legs and Walking Lab, Shirley Ryan AbilityLab, Chicago, Illinois, United States.
Journal of applied physiology (Bethesda, Md. : 1985)
|May 27, 2025
概括
改变脚位置会改变肌肉的长度,影响三肌肌肉的运动单元招募和力量控制. 这揭示了一个神经肌肉策略,用于在脚部flexion期间保持力输出.
科学领域:
- 神经肌肉生理学 神经肌肉生理学
- 生物力学 生物力学
- 发动机控制器的控制器
背景情况:
- 肌肉长度是影响运动控制和力量产生的一个关键因素.
- 三肌肌肉群的协调行动对于脚侧弹至关重要.
- 了解肌肉长度如何影响运动单元行为是阐明神经肌肉策略的关键.
研究的目的:
- 为了研究通过脚位置改变肌肉长度对力量控制的影响.
- 检查运动单元招募值的变化以及三肌内和三肌外肌之间的一致性.
- 为了确定在不同肌肉长度的同位体足部屈曲过程中使用的神经肌肉策略.
主要方法:
- 十六名健康成年人在三种脚位置 (20°脚,0°,20°背部) 进行了对称脚屈曲.
- 高密度表面电肌图记录了胃角肌 (GM,GL) 和肌底肌 (SL,SM) 肌肉的活动.
- 动力单元累积尖峰列车 (MUCST) 分析了连贯性 (三角形,α,β波段) 和招聘值.
主要成果:
- 机动单元的招聘门在GM,SL和SM下降,随着肌肉的延长.
- 随着延长,在SM/SL (三角带) 中观察到GM-SM连贯性和肌内连贯性增加.
- 强力稳定性得到改善,而α频段连贯性和Force-MUCST连贯性下降.
结论:
- 改变的肌肉长度调节了三肌的运动单元招募和共同的突触输入.
- 神经肌肉控制适应不同的肌肉长度,以保持脚部屈曲力输出.
- 这些发现突出了有关反,肌肉特性和下降输入的整合,以实现协同肌肉协调.
相关概念视频
01:20Motor Unit Stimulation
2.0K
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...
2.0K
01:22Somatic Spinal Reflexes
2.8K
Somatic spinal reflexes are rapid, involuntary muscular responses to external stimuli that involve the somatic musculature and the spinal cord.
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
2.8K
01:22Muscle Stimulation Frequency
2.7K
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...
2.7K
01:29Neuromuscular Junction And Blockade
3.7K
The site of chemical communication between a motor neuron and a muscle fiber is called the neuromuscular junction (NMJ). The end of the motor neuron at the NMJ divides into a cluster of synaptic end bulbs. The cytoplasm of these bulbs consists of synaptic vesicles enclosing acetylcholine molecules, the principal neurotransmitter released at the NMJ. The region opposite the synaptic bulb that ends in the muscle fiber is called the motor end plate, which has acetylcholine receptors. Within the...
3.7K
01:29Relaxation of Skeletal Muscles
3.9K
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open....
3.9K
01:13Motor Units
4.8K
The motor unit is a fundamental component of the neuromuscular system and plays a crucial role in coordinating muscle contractions. It consists of a somatic motor neuron, which connects and controls multiple skeletal muscle fibers, forming a single functional segment. The axon of the motor neuron branches out and establishes synaptic connections known as neuromuscular junctions with individual muscle fibers within the motor unit.
Motor units come in different sizes, with smaller units...
Motor units come in different sizes, with smaller units...
4.8K