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Excitation-Contraction Coupling in Skeletal Muscles

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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.
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Knee Joint

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Generation of Action Potential in Skeletal Muscles

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Related Experiment Video

Updated: Sep 13, 2025

Engineering Platform and Experimental Protocol for Design and Evaluation of a Neurally-controlled Powered Transfemoral Prosthesis

Engineering Platform and Experimental Protocol for Design and Evaluation of a Neurally-controlled Powered Transfemoral Prosthesis

Published on: July 22, 2014

A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation.

Shikai Jin¹, Bin Liu¹, Zhuo Wang¹

¹School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, China.

Biomimetics (Basel, Switzerland)

|July 25, 2025

Summary

This summary is machine-generated.

This study introduces a bionic knee exoskeleton with a novel variable stiffness actuator. This design enhances comfort and compliance during various walking patterns, offering muscle support.

Keywords:

artificial muscle elastic actuator knee exoskeleton variable stiffness mechanism

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Published on: January 13, 2022

Area of Science:

Robotics
Biomechanics
Biomedical Engineering

Background:

Exoskeletons require adaptable stiffness for different user needs and activities.
Current designs often lack dynamic stiffness modulation capabilities for natural joint movement.

Purpose of the Study:

To present a novel bionic knee exoskeleton with a variable stiffness actuator.
To investigate the effectiveness of dynamic stiffness modulation for improved gait compliance and comfort.

Main Methods:

Developed a novel rope-driven artificial muscle actuator for variable stiffness.
Created a mathematical model of the knee exoskeleton and analyzed aramid fiber rope properties.
Proposed a control framework and conducted wearable experiments with electromyography (EMG) analysis.

Main Results:

The variable stiffness actuator effectively modulated knee joint stiffness across different gait modes.
Wearable experiments demonstrated improved compliance and comfort during various gait patterns.
EMG results indicated a compensatory effect on the rectus femoris muscle.

Conclusions:

The proposed bionic knee exoskeleton with a variable stiffness actuator is effective for enhancing user comfort and compliance.
This technology shows potential for assistive and rehabilitative applications in gait assistance.