Behind the power curve

What does this mean.........behind the power curve? Thank you.

Behind the power curve is an aviation expression that refers to the point in flight --- usually either coming in for landing or when rapidly slowing down to lose altitude, when the airplanes drag starts to slow it down faster than the engine can recover from quickly. In this case, you can increase the power on the engine, but it will take a while to build up the engine power to again accelerate the airplane. If you have an inconvenient tree in front of you, or a mountain, it is not a very nice position to be in.
The aviation expression has been generalized to refer to situations where you are really behind external circumstances and it will take a lot of catching up to just get even with the outside world.