Reduced oxygen availability can trigger 'circuit breakers' in the brain that reduce oxygen supply to muscles to prevent cognitive impairment.

“it's these things are not just about how much oxygen is making it to the muscle it's also like what is that what is your brain oxygen level and so you're getting these other circuit breakers that are starting to come down that aren't even on this path from mouth to lungs to to blood to muscle there there's other factors that are saying whoa wait a second oxygen is getting a little low so we're going to actually cut off the supply to the muscles or reduce it in order to make sure that we don't get stupid”