He postulated that nerves activate muscles mechanically by carrying a mysterious substance he called pneumata psychikon, usually translated as "animal spirits".

Core Training - Core stability training incorporates movement contractions and specific instruction in order to activate muscles of the core.

He devised a method for activating individual muscles of the face through electronic stimulation.

In the peripheral nervous system, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system.

Normally, calcium ions are used by the body to activate muscles, composed of myofibril cells.

The testicles can also be lifted voluntarily using the pubococcygeus muscle, which partially activates related muscles.

They sent impulses to the brain, where they traveled about and gave rise to impulses which activated glands and muscles, including the motor organs of speech.

Moreover, acetylcholine is used by the nerves to activate muscles.

Voluntary apnea can be achieved by closing the vocal cords, simultaneously keeping the mouth closed and blocking the nasal vestibule, or constantly activating expiratory muscles.

One muscle can be part of multiple muscle synergies, and one synergy can activate multiple muscles.