Related Experiment Video
Updated: May 28, 2026

Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise
Published on: August 25, 2022
Passive trunk loading influences muscle activation during dynamic activity
1Department of Kinesiology, Southern Illinois University, 1075 South Normal Drive, Mailcode 4310, Carbondale, Illinois 62901, USA. mwolson@siu.edu
Introduction:
Repetitive loading of the low back tissues induces tension relaxation with a corresponding variation in the myoelectric response of the neuromuscular system, which may influence low back health. The purpose of this study was to observe trunk muscle activities before and after a passive cyclic trunk flexion-extension exercise.
Methods:
Nineteen participants were subjected to sagittal plane loading of the low back tissues. These individuals performed toe-touching before and over 1 hour after load termination.
Results:
Lumbar paraspinal activity cessation occurred significantly sooner over time during lumbar and pelvic flexion post-loading, as compared with pre-loading. Lumbar paraspinal activity then re-initiated later in lumbar extension. There was no change in peak or average muscle activity during the procedures.
Conclusions:
It is apparent that passive loading of the viscoelastic lumbar tissues results in a prolonged neuromuscular adaptation, followed by possible neuromuscular compensation sustained within 1 hour of load termination.
Related Concept Videos
Motor Unit Stimulation
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...
Alterations in Muscle Tone ll
Isotonic and Isometric Muscle Contractions
Isotonic contractions
Isotonic contractions occur when a muscle changes length while the...
Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Exercise and Muscle Performance
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...
Excitation-Contraction Coupling in Skeletal Muscles
When an action potential...

