EMG response in profound neuromuscular block - LWW ...
journals.lww.com › Home › June 12, 2010 - Volume 27 - Issue 47
by M De Bel - ‎2010 - ‎Cited by 1 - ‎Related articles
12 Jun 2010 - A muscle may contract in response to nerve (indirect) stimulation (IS) as well to direct muscle stimulation (DS). Several studies1, 2 have shown ...

You will find these words in connection with EMG.

Ew. dosł. "intermediate" zamiast "medium".

...the neck EMG was relatively stable and of intermediate amplitude...
...three portions of high, low, and intermediate amplitude, respectively.
http://tinyurl.com/pc3qylq

Sympathetic activation is associated with increases in EMG during fatiguing exercise...
Results of the fatiguing exercise on EMG activity.
http://tinyurl.com/om7u63m

Zapis wysiłkowy może być bogaty, pośredni bogaty, pośredni, ubogi/zubożony - widać to tutaj: http://tinyurl.com/n2q9ckm [od drugiego tekstu, nie po kolei]

Natomiast "voluntary contraction" to coś innego:

...do wartości referencyjnej (tj. maksymalnego dowolnego skurczu
- maximum voluntary contraction, MVC) dla skurczu referencyjnego...
http://tinyurl.com/o5wr33k

Jeśli chodzi o sam imiesłów "fatiguing", to bardzo dobrze googluje się też termin "fatiguing contraction".

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Note added at 14 hrs (2014-06-12 23:52:55 GMT)
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Generalnie: jeśli nie ma w użyciu krótkiego odpowiednika, to lepiej dać długie tłumaczenie opisowe niż krótką kalkę z języka źródłowego na docelowy (kalka taka może być zupełnie niezrozumiała dla odbiorcy znającego tylko język docelowy).

Measurements are made at rest (zapis spoczynkowy) or during muscle activity/contraction (zapis wysiłkowy).

"When the patient makes a stronger contraction, more motor units are recruited and potentials overlap and interfere with each other; hence this is sometimes referred to as the interference pattern. Recruitment pattern is now the preferred term. At maximal voluntary activation, a full recruitment pattern is produced which fills the baseline. A reduced pattern occurs when despite maximal activation, which of course must be assessed clinically, areas of baseline without activity can still be seen."
https://jnnp.bmj.com/content/76/suppl_2/ii32

During a maximal voluntary muscle contraction of a healthy individual, a "full" or "complete" interference pattern is present. No individual MUAPs can be identified clearly (this is normal). The baseline is obscured completely by motor unit activity.

Incomplete interference pattern may be divided as follows:

Reduced interference pattern (ie, intermediate interference pattern): Some of the individual MUAPs may be identified, while other individual MUAPs cannot be identified because of overlap.

Discrete activity: Each of several different MUAPs can be identified. See the image below.

Incomplete interference pattern. This example shows a discrete interference pattern in a patient with amyotrophic lateral sclerosis. Despite maximal voluntary effort, individual MUAPs can be identified and the baseline is partly visible.

Single unit pattern: A single motor unit fires at rapid rate during maximum voluntary effort.
https://emedicine.medscape.com/article/1141359-overview