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Related Experiment Video

Updated: Oct 16, 2025

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo

Published on: December 5, 2012

Motor unit firing patterns on increasing force during force and position tasks.

Shun Kunugi¹, Aleš Holobar², Tsutomu Kodera³

¹Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan.

Journal of Neurophysiology

|October 20, 2021

Summary

Motor unit firing rate regulation is similar between force and position tasks during ankle plantarflexion. This study found consistent motor unit responses in the medial gastrocnemius muscle when increasing force in both tasks.

Keywords:

EMG firing rate force motor unit position

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Related Experiment Videos

Last Updated: Oct 16, 2025

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo

Published on: December 5, 2012

Force and Position Control in Humans - The Role of Augmented Feedback

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Published on: June 19, 2016

Functional Isolation of Single Motor Units of Rat Medial Gastrocnemius Muscle

Functional Isolation of Single Motor Units of Rat Medial Gastrocnemius Muscle

Published on: December 26, 2020

Area of Science:

Neuroscience
Motor Control
Biomechanics

Background:

Different neurophysiological strategies are employed for angle adjustments in tasks like driving versus force control.
The specific differences in motor unit behavior during increasing force exertion between these tasks remain unclear.

Purpose of the Study:

To investigate and compare motor unit responsiveness to increasing force in distinct force and position control tasks.
To understand how the medial gastrocnemius muscle regulates motor unit firing during ankle plantarflexion in different task contexts.

Main Methods:

Twelve healthy participants performed ramp and hold ankle plantarflexion contractions.
Tasks included a rigid pedal (force task) and a free pedal with inertial load (position task) at 20% and 30% maximal voluntary contraction.
High-density surface electromyography of the medial gastrocnemius was used to decompose and analyze individual motor unit firing patterns.

Main Results:

Motor unit analysis tracked 90-109 motor units across tasks and torque levels.
Mean firing rate increased, and firing rate variability decreased with force gain in both tasks.
No significant differences in these motor unit responses were observed between the force and position tasks.

Conclusions:

Motor unit firing rate is regulated similarly in the medial gastrocnemius muscle during increasing force exertion for both force and position tasks.
Despite potential implications for fatigue in position tasks, force regulation appears consistent across these task types.