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Related Concept Videos

Relaxation of Skeletal Muscles01:29

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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....
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Generation of Action Potential in Skeletal Muscles01:24

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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.
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Motor Unit Stimulation01:20

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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.
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Exercise and Muscle Performance01:27

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Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
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Muscle Stimulation Frequency01:22

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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
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Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
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Measurement of Maximum Isometric Force Generated by Permeabilized Skeletal Muscle Fibers
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Force training induces changes in human muscle membrane properties.

Werner J Z'Graggen1,2, Joël P Trautmann2, Hugh Bostock3

  • 1Department of Neurosurgery, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.

Muscle & Nerve
|April 23, 2016
PubMed
Summary
This summary is machine-generated.

Muscle force training alters human muscle membrane properties. Two weeks of training reduced the relative refractory period and increased early supernormality, suggesting changes in ion channel function.

Keywords:
early supernormalityforce trainingmuscle membrane potentialmuscle velocity recovery cyclerelative refractory period

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Area of Science:

  • Physiology
  • Neuroscience
  • Exercise Science

Background:

  • Human muscle membrane properties are crucial for muscle function.
  • Muscle velocity recovery cycles (MVRCs) offer an in vivo method to assess these properties.
  • Understanding how training affects membrane excitability is important for optimizing performance and rehabilitation.

Purpose of the Study:

  • To investigate the impact of muscle force training on MVRC parameters.
  • To quantify changes in relative refractory period and supernormality following a training intervention.

Main Methods:

  • MVRCs were recorded from the brachioradialis muscle in 12 healthy subjects.
  • Measurements were taken before and after a 2-week muscle force training program.
  • The effects of 1 to 5 conditioning stimuli on MVRC parameters were analyzed.

Main Results:

  • Muscle force training significantly reduced the relative refractory period (P < 0.0001).
  • Early supernormality was significantly increased (P < 0.02) and occurred earlier (P < 0.01).
  • Late supernormality remained unchanged, irrespective of the number of conditioning stimuli.

Conclusions:

  • Muscle force training induces changes in muscle membrane excitability.
  • Observed effects suggest hyperpolarization of the resting membrane potential, potentially due to increased sodium pump activity.
  • These findings provide insights into the physiological adaptations to resistance training at the cellular level.