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Related Experiment Video

Updated: Apr 30, 2026

Measuring the Motor Aspect of Cancer-Related Fatigue using a Handheld Dynamometer

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Published on: February 20, 2020

Electrically induced torque decrease reflects more than muscle fatigue.

Maria Papaiordanidou¹, Jean-Damien Stevenot, Valerie Mustacchi

¹UMR7287, Institut des Sciences du Mouvement, CNRS, Faculté des Sciences du Sport, Aix-Marseille University, 163 avenue de Luminy, 13288, Marseille, France.

|May 7, 2014

Summary

Different electrical stimulation (ES) protocols were compared for their ability to induce fatigue in the triceps surae muscle. Results indicate that 100-Hz protocols may involve mechanisms beyond direct motor unit fatigue.

Keywords:

excitability threshold maximal voluntary contraction mechanical twitch stimulation parameters voluntary activation

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Area of Science:

Neuromuscular Physiology
Exercise Physiology
Biomedical Engineering

Background:

Electrical stimulation (ES) is used to induce muscle contractions and study fatigue.
Understanding how different ES parameters affect muscle fatigue is crucial for optimizing training and rehabilitation protocols.
Previous research has explored various frequencies and pulse widths, but direct comparisons of their fatigue-inducing effects are limited.

Purpose of the Study:

To compare the fatigue induced by four different electrical stimulation (ES) protocols in the triceps surae muscle.
To investigate the relationship between torque decrease during ES and changes in muscle activation and excitability.
To explore potential mechanisms underlying fatigue during different ES frequencies and pulse widths.

Main Methods:

Eight healthy subjects underwent fatigue protocols using four ES settings (30 Hz-500 μs, 30 Hz-1 ms, 100 Hz-1 ms, 100 Hz-500 μs).
Stimulations consisted of 60 trains (4s on, 6s off) at an intensity eliciting 30% of maximal voluntary contraction (MVC).
Fatigue was quantified by decreases in ES and MVC torque, and twitch amplitude at stimulation intensity (Istim) was analyzed.

Main Results:

All ES protocols significantly decreased ES torque, MVC torque, and twitch amplitude.
The decrease in ES torque positively correlated with the decrease in twitch amplitude at Istim, but only for the 30-Hz protocols.
During 100-Hz protocols, observed fatigue effects may involve factors other than direct motor unit fatigue, such as altered axonal excitability.

Conclusions:

Both 30-Hz and 100-Hz ES protocols induce significant muscle fatigue in the triceps surae.
The relationship between torque loss and twitch response differs between low (30 Hz) and high (100 Hz) stimulation frequencies.
High-frequency ES may recruit additional physiological mechanisms contributing to fatigue, potentially involving changes in nerve excitability.