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Related Concept Videos

Motor Unit Stimulation01:20

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...
Excitation-Contraction Coupling in Skeletal Muscles01:20

Excitation-Contraction Coupling in Skeletal Muscles

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 potential...
Muscle Stimulation Frequency01:22

Muscle Stimulation Frequency

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...
Relaxation of Skeletal Muscles01:29

Relaxation of Skeletal Muscles

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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Related Experiment Video

Updated: May 10, 2026

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing
06:42

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing

Published on: August 25, 2022

Trunk muscle activation during golf swing: Baseline and threshold.

Luís Silva1, Sérgio Marta, João Vaz

  • 1Faculty of Human Kinetics, Technical University of Lisbon, Portugal. luisbsilva@hotmail.com

Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology
|July 3, 2013
PubMed
Summary

Electromyography (EMG) onset detection in golf swings depends on the chosen method and specific muscle. External oblique (EO) muscles activate first, but algorithm reliability varies by muscle and side.

Keywords:
EMGGolf swingOnsetThresholdTrunk

More Related Videos

Method to Measure Tone of Axial and Proximal Muscle
10:41

Method to Measure Tone of Axial and Proximal Muscle

Published on: December 14, 2011

Related Experiment Videos

Last Updated: May 10, 2026

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing
06:42

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing

Published on: August 25, 2022

Method to Measure Tone of Axial and Proximal Muscle
10:41

Method to Measure Tone of Axial and Proximal Muscle

Published on: December 14, 2011

Area of Science:

  • Biomechanics
  • Motor Control
  • Sports Science

Background:

  • Electromyography (EMG) temporal analysis is understudied in complex dynamic movements like the golf swing.
  • Accurate EMG onset detection is crucial for understanding muscle activation patterns during athletic performance.

Purpose of the Study:

  • To analyze EMG onset during the golf swing.
  • To compare the reliability of two different threshold methods for EMG onset detection.
  • To investigate the influence of different golf clubs on EMG onset.

Main Methods:

  • Two threshold methods (Method A: baseline between MVCs; Method B: pre-swing mean) were compared.
  • EMG data from Rectus Abdominis (RA), Erector Spinae (ES), and External Oblique (EO) muscles were analyzed.
  • Three-way repeated measures ANOVA and Intraclass Correlation Coefficient (ICC) were used for statistical analysis.

Main Results:

  • Club type did not significantly influence EMG onset detection.
  • Rectus Abdominis (RA) demonstrated the highest agreement between the two methods.
  • Erector Spinae (ES) showed very low agreement, potentially due to pre-swing postural activity.
  • External Oblique (EO) was the first muscle activated (1295ms before impact), with similar timing on both sides.
  • The right External Oblique (EO) showed better inter-method agreement than the left.

Conclusions:

  • EMG onset detection algorithms are dependent on the specific task and muscle being analyzed.
  • Methodological choices significantly impact EMG onset detection reliability in golf swing analysis.
  • Understanding muscle activation sequencing, like the early activation of EO, is key for optimizing golf performance and injury prevention.