诱导后激活增强会改变在不受约束的速度收缩过程中肘部扩展器的人类运动单元的行为
Alexander M Zero1, Charles L Rice1,2
1School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada.
Journal of neurophysiology
|October 16, 2024
概括
后激活强化 (PAP) 增加了动力单元 (MU) 招募值,但在动态收缩期间降低了发射率. 这表明MU活动适应以优化基于先前活动的肌肉输出.
科学领域:
- 神经肌肉生理学 神经肌肉生理学
- 发动机控制器的控制器
- 肌肉生理学 肌肉生理学
背景情况:
- 后激活强化 (PAP) 是一种现象,在短时间的高强度肌肉活动中,会增加随后的肌肉力量产生.
- 了解PAP如何影响动态收缩期间的运动单元 (MU) 行为,对于优化训练和表现至关重要.
研究的目的:
- 为了研究诱导PAP在动态同位素肘部延伸期间对MU活动的影响.
- 为了比较PAP在动态收缩期间对MU活动的影响,与之前研究的异度任务相比.
主要方法:
- 在12名参与者中,在50%和75%的峰值功率下,在肘部延伸过程中记录了前肌和侧肌的MU活动.
- 使用条件收缩和随后的电刺激诱导PAP,验证抽扭矩的强化.
- 分析了MU的招聘门和带有和没有PAP的解雇率.
主要成果:
- PAP显著提高了MU招聘门的40-80%,并降低了50%和75%的峰值功率的平均和瞬间发射率.
- 发射率从50%增加到75%的功率,但75%的潜在收缩显示出比50%的基线更低的发射率.
- 动态收缩表明,与异度任务相比,在更广泛的强度范围内,PAP对MU活动的影响更大.
结论:
- 动态收缩期间的MU活动是响应激活历史和力强化.
- 外围反不太可能是MU修改的主要驱动因素,因为在招聘值发生了变化.
- 动态收缩为评估PAP对MU行为和肌肉输出优化影响提供了一个更具功能性的模型.
相关概念视频
Motor Unit Stimulation
1.5K
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...
1.5K
Muscle Stimulation Frequency
2.0K
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...
2.0K
Generation of Action Potential in Skeletal Muscles
4.2K
Every cell in the body maintains a membrane potential due to an uneven distribution of positive and negative charges across its plasma membrane. The membrane potential is measured in millivolts and quantifies the difference in charge across the membrane.
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the...
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the...
4.2K
Excitation-Contraction Coupling in Skeletal Muscles
7.9K
Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action...
When an action...
7.9K
Relaxation of Skeletal Muscles
3.1K
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....
3.1K


