Related Experiment Video
Updated: Jun 25, 2026
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Time and frequency domain analysis of surface myoelectric signals during electrically-elicited cramps
M A Minetto1, A Botter, D De Grandis
1Division of Endocrinology, Department of Internal Medicine, Molinette Hospital, University of Turin, 10126 Turin, Italy. marcominetto@libero.it
Objectives:
To examine if different frequencies of electrical stimulation trigger different sized cramps in the abductor hallucis muscle and to analyze their surface electromyographic (EMG) behaviour in both time and frequency domains.
Methods:
Fifteen subjects were studied. Stimulation trains of 150 pulses were applied to the muscle motor point. Frequency was increased (starting from 4pps with 2-pps steps) until a cramp developed. Current intensity was 30% higher than that eliciting maximal M-waves. After the first cramp ("threshold cramp"), a 30-minute rest was provided before a second cramp ("above-threshold cramp") was elicited with a frequency increased by 50% with respect to that eliciting the first cramp.
Results:
We found greater EMG amplitude and a compression of the power spectrum for above-threshold cramps with respect to threshold cramps. M-wave changes (ranging between small decreases of M-wave amplitude to complete M-wave disappearance) occurred and progressively increased throughout stimulation trains. Significant positive correlations were found between estimates of EMG amplitude during cramps and estimated reductions of M-wave amplitude.
Conclusions:
Varying frequencies of electrical stimulation triggered different sized cramps. Moreover, decreases in M-wave amplitude were observed during both threshold and above-threshold stimulations. The choice of the stimulation frequency has relevance for optimizing electrical stimulation protocols for the study of muscle cramps in both healthy and pathological subjects.
Related Concept Videos
01:22Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:20Motor 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...
01:24Generation of Action Potential in Skeletal Muscles
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the cell's...