The heart muscles contract to expel the blood.

心脏肌肉收缩以挤压出血液。

《牛津词典》

All right, your muscles contract.

好的，你的肌肉收缩。

youdao

Muscles contract by a sliding-filament mechanism.

肌肉以滑动丝的机制产生收缩。

youdao

Less grimly, electric currents have been used for years by physical therapists to make muscles contract as a way of stimulating and strengthening them.

FORBES: Backrubs From A PDA

Oxygen is the fuel that muscles need to contract.

CNN: Claudication

The information on how much to contract is translated into pulses of electricity that are sent to each of the relevant muscles and bingo!

ECONOMIST: We can rebuild him. We have the technology