Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Motor Unit Stimulation

Motor Unit Stimulation

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...

Correlation between ECG and Cardiac Cycle

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...

Isotonic and Isometric Muscle Contractions

Isotonic and Isometric Muscle Contractions

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 the...

Variability: Analysis

Variability: Analysis

Measures of variability are statistical metrics that reveal the dispersion pattern within a dataset. They are pivotal in biostatistics, providing insights into the heterogeneity within health and biological data. Variability signifies the degree to which data points diverge from one another, helping researchers understand the potential range of values and associated uncertainty within the data.
The range is a simple measure of variability, indicating the difference between the highest and...

You might also read

Related Articles

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

Sort by

Same author

Monoclonal nephritic factors reveal insights into C3 convertase dynamics and dysregulation.

bioRxiv : the preprint server for biology·2026

Same author

Acquired drivers of C3 glomerulopathy.

Clinical kidney journal·2025

Same author

Altered neural recruitment during single and dual tasks in athletes with repeat concussion.

Frontiers in human neuroscience·2024

Same author

Altered neural recruitment despite dual task performance recovery in athletes with repeat concussion.

medRxiv : the preprint server for health sciences·2024

Same author

ETV4-Dependent Transcriptional Plasticity Maintains MYC Expression and Results in IMiD Resistance in Multiple Myeloma.

Blood cancer discovery·2023

Same author

Transcriptional Heterogeneity Overcomes Super-Enhancer Disrupting Drug Combinations in Multiple Myeloma.

Blood cancer discovery·2023

Search research articles

Related Experiment Video

Updated: Jul 5, 2026

Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity

Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity

Published on: June 12, 2019

Motor variability: within-subject correlations during separate and simultaneous contractions.

Brian L Tracy¹, Devin V Dinenno, Bjørn Jørgensen

¹Department of Health and Exercise Science, Colorado State University, 220 Moby-B Complex, Fort Collins, CO 80523-1582, USA. tracybl@cahs.colostate.edu

Experimental Brain Research

|May 15, 2008

Summary

Motor variability in elbow and knee muscles shows similar patterns between young and elderly adults, suggesting shared neural control mechanisms. These similarities are more pronounced in elderly individuals, especially at lower force levels.

More Related Videos

Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Published on: September 3, 2015

Combining Multiple Data Acquisition Systems to Study Corticospinal Output and Multi-segment Biomechanics

Combining Multiple Data Acquisition Systems to Study Corticospinal Output and Multi-segment Biomechanics

Published on: January 9, 2016

Related Experiment Videos

Last Updated: Jul 5, 2026

Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity

Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity

Published on: June 12, 2019

Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Published on: September 3, 2015

Combining Multiple Data Acquisition Systems to Study Corticospinal Output and Multi-segment Biomechanics

Combining Multiple Data Acquisition Systems to Study Corticospinal Output and Multi-segment Biomechanics

Published on: January 9, 2016

Area of Science:

Neuroscience
Motor Control
Human Physiology

Background:

Motor variability, the fluctuations in force output during sustained contractions, is a key characteristic of neuromuscular control.
Understanding the similarities and differences in motor variability between different muscle groups and age populations can reveal insights into the underlying neural control strategies.

Purpose of the Study:

To investigate the similarity of motor variability between proximal muscles (elbow flexors and knee extensors) in young and elderly adults.
To examine how factors like contraction intensity, task condition (separate vs. simultaneous contractions), and visual feedback influence inter-muscle motor variability.

Main Methods:

Young and elderly adults performed steady elbow flexor (EF) and knee extensor (KE) contractions under various conditions (intensity, separate/simultaneous, with/without visual feedback).
Analysis included correlations of fluctuation amplitude (SD, CV), time-based cross-correlations (CC), force power spectra, and frequency-based coherence (COH) of concurrent force records.

Main Results:

Correlations in force fluctuation amplitude were significant across most conditions, indicating similar variability patterns between EF and KE muscles.
Cross-correlations (CC) were generally low but stronger in elderly adults during simultaneous contractions.
Force fluctuations were predominantly at low frequencies (<4 Hz), with age-dependent differences in coherence (COH) observed at specific frequency bands.

Conclusions:

The findings suggest that proximal muscle motor neuron pools share common input and transform neural signals similarly, potentially influencing each other.
Age-related differences in cross-correlations and coherence indicate that elderly adults may exhibit more synchronized neural input to remote motor neuron pools, particularly at low frequencies.