Effects of stimulation frequency, amplitude, and impulse width on muscle fatigue.
BACKGROUND
We investigated the effect of stimulation intensity (in percent of maximal tolerated stimulation current, mTSC), frequency, and impulse width on muscle fatigue.


METHODS
Using a randomized crossover design, 6 parameter combinations (80% mTSC, 80 Hz, 400 μs; 60% mTSC, 80 Hz, 400 μs; 80% mTSC, 20 Hz, 400 μs; 60% mTSC, 20 Hz, 400 μs; 80% mTSC, 80 Hz, 150 μs; 60% mTSC, 80 Hz, 150 μs) were tested in both legs of 13 athletic men (age 26 ± 2.3). The slope of the linear regression line over all tetani (FIS) and the number of tetani whose force was above 50% of the initial tetanus (FIN) were used to quantify fatigue.


RESULTS
FIS and FIN were significantly lower in high-frequency protocols. No effects on FIS and FIN were found for intensity and impulse width.


CONCLUSIONS
Stimulation frequency, but not impulse width or intensity, affected fatigue kinetics.
Institute for Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany.
Michael
M
Behringer
Institute for Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany.
Sebastian
S
Grützner
Institute for Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany.
Johannes
J
Montag
Institute for Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany.
Molly
M
McCourt
Digital Sports Group, Pattern Recognition Lab, Friedrich-Alexander University Erlangen-Nuremberg, Germany.
Matthias
M
Ring
Institute for Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany.
Joachim
J
Mester
D000328:Adult; D018592:Cross-Over Studies; D004558:Electric Stimulation / Q000379:methods; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D055815:Young Adult
electrical stimulation; frequency; impulse width; intensity; muscle fatigue