они напрягаются

tense up, strain themselves, become tense

n ə p rʲ ɪ ɡ a j ʊ t͡s ə → напрягаться

на onto/on; accumulation or completion + пряг strain, exert + а verb-forming suffix + ют 3rd person plural present + ся reflexive marker

verb · third plural · present indicative Rare #49,779

tense up, strain themselves, become tense

RU: Мышцы напрягаются во время упражнения.

EN: The muscles tense up during the exercise.

My arms are tense!

— Зеркало (1975)

My arms tense up.

— Зеркало (1975)

The fingers tense up.

— Зеркало (1975)

The hands are getting more and more tense.

— Зеркало (1975)