What does the phrase in capital letters means in this context?
Stress is a survival mechanism. When danger appears, it can get you out of trouble quickly. Your body CRASHES UP THE GEARS and throws all its resources into getting you moving.
What does the phrase in capital letters means in this context?
Stress is a survival mechanism. When danger appears, it can get you out of trouble quickly. Your body CRASHES UP THE GEARS and throws all its resources into getting you moving.
It’s (probably) originally a malapropism for CRANKS up the gear(s). A quick search online for "crank up the gears" finds a lot of quite literal uses mostly related to cycling and motor racing.
The crank1 stems from the action to start a car engine running, many many years ago before starter motors.
Then crank up (see previous reference) came to mean to increase or improve the amount of something or its performance.
Crank up the gears is metaphorical usage, referring to putting a vehicle into its top gear, although the example you cite would be more accurately, er, metaphored as stoking the boiler or stirring up the fire(s) …
Amusingly, Cambridge marks crank up [something] 2 as American English ...
1 Oxford Living Dictionaries
2 Cambridge Dictionaries