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Related Concept Videos

Motor Unit Stimulation01:20

Motor Unit Stimulation

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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.
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...
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Exercise and Muscle Performance01:27

Exercise and Muscle Performance

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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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The Neuromuscular Junction01:19

The Neuromuscular Junction

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The nervous system consists of complex motor neuron circuits, including upper motor neurons originating from the cerebral cortex and lower motor neurons starting in the spinal cord, coordinating both voluntary and involuntary movements. Among these, somatic motor neurons activate skeletal muscles and are classified into alpha, beta, and gamma types. Alpha neurons are vital for voluntary movement coordination, while gamma neurons adjust muscle spindle sensitivity, and the function of beta...
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Relaxation of Skeletal Muscles01:29

Relaxation of Skeletal Muscles

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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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Isotonic and Isometric Muscle Contractions01:22

Isotonic and Isometric Muscle Contractions

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Two primary types of muscle contractions are isotonic and isometric, each serving unique functions and involving distinct mechanisms. Both isotonic and isometric contractions are integral to the body's complex system of movement and stability. Isotonic exercises contribute significantly to functional strength and movement, while isometric contractions are crucial for maintaining posture and joint stability.
Isotonic contractions
Isotonic contractions occur when a muscle changes length while...
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Muscle Stimulation Frequency01:22

Muscle Stimulation Frequency

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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
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
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Related Experiment Video

Updated: Oct 27, 2025

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
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Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention

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Neuromuscular training programs predominantly include instructions that promote an internal focus.

Molly A Stewart1, Lindsey A Waite1, Jithmie G Jayawickrema2

  • 1Physical Therapy Program, Department of Health Professions, University of Wisconsin-La Crosse, La Crosse, WI, USA.

The Journal of Sports Medicine and Physical Fitness
|July 23, 2021
PubMed
Summary

Neuromuscular training for anterior cruciate ligament (ACL) injury prevention often uses internal focus cues. Shifting to an external focus in training instructions may enhance program effectiveness for athletes.

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Area of Science:

  • Sports Medicine
  • Biomechanics
  • Injury Prevention

Background:

  • Neuromuscular training is crucial for anterior cruciate ligament (ACL) injury prevention.
  • External focus instructions may improve training efficacy compared to internal focus.
  • Current popular ACL injury prevention programs predominantly use internal focus cues.

Purpose of the Study:

  • To analyze the focus of technique-related instructions in widely used ACL injury prevention programs.
  • To compare the proportion of internal versus external focus instructions across different exercise types.

Main Methods:

  • Examined instructions from FIFA 11+, HarmoKnee, Knakontroll, and Prevent Injury and Enhance Performance programs.
  • Categorized instructions as promoting internal or external focus.
  • Analyzed instructions for movement retraining, strengthening, plyometrics, and balance exercises.

Main Results:

  • The majority of instructions across all programs promoted an internal focus.
  • Internal focus instructions dominated movement retraining (≥83.3%) and exercises (≥75.0%).
  • Popular ACL prevention programs largely rely on internal focus cues.

Conclusions:

  • Current popular neuromuscular training programs for ACL injury prevention predominantly utilize internal focus instructions.
  • Modifying programs to incorporate more external focus cues could enhance their effectiveness.
  • Optimizing attentional focus may improve ACL injury prevention strategies.