JIC... A word smith will likely make an easier read

- but the message is the same..
Choking...
A kite has to perform the same as an aeroplane wing or a windsurfing sail or a bird's wing or any aerofoil.. When the air is flowing smoothly over/under the foil it works, when the air flow is not smooth it does not work.
Smooth....(laminar etc etc)
The air flow (visualise a parcel of air call it A) splits at the leading edge of your kite - over the top (Atop) and underneath (Abottom) - leaving the trailing edge Atop & ABottom rejoin to make A again.
Not smooth = non-laminar (causing choking) Atop does not meet Abottom at the trailing edge of your kite.
So - try sticking your hand out the window of your car when you are going at least 50 KM/h Start with it level to the ground, then gradually angle your hand up. You should feel it lifting until about 3/4 of the way to being vertical - at that point your hand can start getting pushed up/down - the airflow is going non-laminar = choking. . At vertical it is way harder to hold steady = a flat surface against the wind no lift at all just drag...
Now back to the kite when it starts the upstroke - it is going slowly and the airflow is likely very near that 3/4 point - if you bar in it goes past 3/4's towards vertical - = non laminar and chokes (in aeroplanes it is called a stall) - If you bar out you turn back from 3/4 point towards the airflow - the kite speeds up as the flow speeds up (less drag) and generates more power - etc etc.
The trick to lift is Atop has to travel further over the top surface of the aero foil than Abottom to re-join at the trailing edge - this creates a slight vacuum on the top surface which lifts the aero foil (your power) towards the vacuum to try and remove the energy gradient.
When the air flow becomes non-laminar you loose this vacuum (and your power). Why does it become non-laminar? - The change in airflow direction at the kite leading edge on your up stroke can be 75+ degrees basically getting up toward a right angle - too much energy (mass) in the wrong direction - to smoothly flow around the surface - and U loose the aero foil principle.
You might get another tip or 2 from these posts...
www.seabreeze.com.au/forums/Kitesurfing/Newbies-Tips-Tricks/help-on-riding-the-board/www.seabreeze.com.au/forums/Kitesurfing/Newbies-Tips-Tricks/keeping-the-speed-on/Gateman is on the money - like riding a bike - once have learnt U do not forget
cheers
AP