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Related Experiment Video

Updated: Jun 20, 2026

Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise

Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise

Published on: August 25, 2022

Trunk muscle activation during sub-maximal extension efforts.

Michael W Olson¹

¹Department of Kinesiology, Southern Illinois University Carbondale, 1075 South Normal Ave. Mailcode 4310, Carbondale, IL 62901, USA. mwolson@siu.edu <mwolson@siu.edu>

|September 1, 2009

Summary

Neuromuscular fatigue in trunk muscles like the lumbar paraspinal muscles was observed during sub-maximal isometric trunk extension. Abdominal muscle activation did not significantly increase, suggesting altered motor control strategies for maintaining trunk stability.

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Area of Science:

Biomechanics
Motor Control
Exercise Physiology

Background:

Neuromuscular fatigue of trunk muscles is crucial for assessing motor control.
Understanding muscle activation patterns during fatiguing contractions is key for trunk stability.

Purpose of the Study:

To investigate changes in agonist and antagonist trunk muscle activation during sub-maximal isometric trunk extension.
To evaluate the effects of induced neuromuscular fatigue on lumbar paraspinal and abdominal muscle activity.

Main Methods:

Thirteen women performed maximal voluntary isometric trunk extension at 50% and 70% effort.
Surface electromyography recorded activity of lumbar paraspinal, rectus abdominis, and external oblique muscles.
Torque, median frequency, and normalized integrated electromyography were analyzed over time.

Main Results:

Lumbar paraspinal muscles exhibited significant signs of fatigue under both 50% and 70% effort conditions.
Abdominal muscle activity did not significantly increase during the 70% effort, despite a trend towards increased activation.
Reduced median frequency in lumbar paraspinal muscles coincided with a non-significant trend in abdominal muscle activation.

Conclusions:

The neuromuscular system adapts motor control strategies to maintain force output during trunk muscle fatigue.
These findings are vital for understanding trunk stability mechanisms in preventative and rehabilitative strategies.