be out on (one's) feet

1. To be near to the point of collapse or unconsciousness (as due to exhaustion or injury) but still remaining on one's feet; just short of being asleep or unconscious. Doctors in training are expected to endure an unbelievable amount of stress and exhaustion. Surely it is counterproductive forcing them to attend each of their patients while they're out on their feet. We were all out on our feet after spending nearly an entire day traveling. Get the stroller, Betsy is just about out on her feet after a full day at Disney World.

2. To be all but or as good as defeated; still functioning, but past the point of usefulness or productivity. The company has managed to remain open, but truth be told, it's really been out on its feet for the last year. Our research has been dead on its feet for a while, so I doubt we'll get funded for another year. A: "Do you think filming will continue now that the lead actor has pulled out?" B: "Not a chance. It's out on its feet."