Ive heard that humans have extreme strength but the body blocks itself from exerting 100% of it. is this tru?

ive heard that even women have enough strength to lift almost 80lb on each arm but in everyday life, the body puts a 'lock' on itself so humans can stay in control. this lock is unlocked when the body is in extreme conditions for example, when a person is under a heavy obstacle, etc. is this a myth or is this true? if it is true, is there a way to release this lock on purpose?