Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Motor Unit Stimulation01:20

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...
1.5K
Motor Units01:13

Motor Units

3.9K
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...
3.9K
Generation of Action Potential in Skeletal Muscles01:24

Generation of Action Potential in Skeletal Muscles

4.4K
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...
4.4K
Muscle Stimulation Frequency01:22

Muscle Stimulation Frequency

2.1K
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...
2.1K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Sensitivity of Nerve and Skin Biopsy and Fat Aspirate for Amyloid in Symptomatic Hereditary ATTR Amyloidosis With Peripheral Neuropathy.

Neurology·2026
Same author

Ultrasound-Guided Near-Nerve Needle Assessment of the End-to-Side Anterior Interosseous to Ulnar Motor Nerve Transfer Contribution to Hand Intrinsic Reinnervation in Compressive Ulnar Neuropathy.

Muscle & nerve·2026
Same author

Athletes who return to sport after treatment for shoulder instability exhibit higher psychological readiness: a systematic review.

JSES international·2025
Same author

Evaluation of spin in systematic reviews and meta-analyses involving glenoid augmentation in total shoulder arthroplasty.

JSES international·2025
Same author

Factors That Predict Endoscopic Evaluation and Gastrostomy Placement in Patients With Neurologic Disorders and Dysphagia.

Cureus·2025
Same author

Heart Transplantation for Cardiac Amyloidosis: Mayo Clinic Consensus Statement.

Mayo Clinic proceedings·2025

Related Experiment Video

Updated: Jun 25, 2025

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
07:53

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation

Published on: September 13, 2015

21.9K

Motor unit potential recruitment reference values in common upper and lower extremity muscles.

Devon I Rubin1, Christopher J Lamb1

  • 1Electromyography Laboratory, Department of Neurology, Mayo Clinic, Jacksonville, FL, USA.

Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology
|May 22, 2024
PubMed
Summary

New reference values for motor unit (MU) firing rates in needle EMG can help detect reduced MU recruitment. Rates above 15 Hz at multiple sites may indicate reduced recruitment in common muscles.

Keywords:
Firing frequencyMotor unit potentialNeedle electromyographyRecruitmentRecruitment ratioReference values

More Related Videos

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases
06:08

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases

Published on: April 19, 2024

367
Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles
09:07

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles

Published on: September 25, 2015

21.2K

Related Experiment Videos

Last Updated: Jun 25, 2025

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
07:53

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation

Published on: September 13, 2015

21.9K
Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases
06:08

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases

Published on: April 19, 2024

367
Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles
09:07

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles

Published on: September 25, 2015

21.2K

Area of Science:

  • Neurology
  • Electromyography
  • Motor Unit Physiology

Background:

  • Accurate assessment of motor unit (MU) recruitment is crucial for diagnosing neuromuscular disorders.
  • Establishing normative data for MU electrophysiological parameters is essential for reliable clinical interpretation.

Purpose of the Study:

  • To establish reference values for motor unit (MU) recruitment during needle electromyography (EMG) in six common muscles.
  • To define upper limits of normal for fastest MU firing rates and recruitment ratios at low to moderate contractions.

Main Methods:

  • Needle EMG was performed on 111 healthy subjects across six muscles.
  • Fastest MU firing rates and recruitment ratios (RRs) were measured at multiple sites within each muscle.
  • The 97th percentile was used to determine upper limits of normal for these parameters.

Main Results:

  • Upper limits of normal for fastest MU firing rates ranged from 12-15 Hz.
  • Slightly higher fastest firing rates were observed in the deltoid and triceps muscles compared to others.
  • Recruitment ratios showed variability, but fastest MU firing rates did not correlate with RR variations.

Conclusions:

  • Fastest MU firing rates exceeding 15 Hz at multiple sites suggest reduced MU recruitment.
  • Rates above 12 Hz in certain muscles may indicate mildly reduced recruitment.
  • Defined reference values for fastest MU firing rates enhance the accuracy of identifying reduced MU recruitment.