I’m glad you could help your friend with MS, @belgianWBLuver.
Personally I have not had many problems with horses lugging at the bit. I am just too weak to hold the horse’s head up, if the horse starts lugging he gets my invitation (legs, loose fingers) to go on stretching down while the reins slide through my fingers. After a while the problem disappears for me though I might have to go through some time with the horse’s nose almost touching the ground. Eventually the horse figures out how to carry his own head.
Littauer gets into this. That the horse needs to get strong enough to carry his head higher, and with the logical and rational Forward Seat schooling it is inevitable.
I just don’t get hung up about where the horse’s head is at. All it takes is time, intelligent schooling, patience, and soft responsive hands. It has worked every time for me.
The last decade, under the eyes of my riding instructor, I finally figured out for sure that if I can get the horse to reach for contact with his tongue first I am well on my way to a responsive mouth. My contact is in ounces (1 ounce=28 grams), my hand aids are in grams with immediate release. The horses will willingly reach for contact with me in spite of my hand tremors and me not always realizing where my hands are, so long as my fingers are loose and supple the horses forgive me all of my hand faults once they understand what I mean with a certain rein aid.
I really liked seeing Phillipe Karl’s method. I absolutely refuse to ride a horse behind vertical, I only used side reins lunging once my whole life (I did not like the horse going behind vertical.) I’ve taken my nosebands off the bridle, if the horse feels it necessary to open his mouth because my hands are too harsh, well I just have to lighten my hands until the horse stops opening his mouth. Bitless is fine for trail riding or if it is really cold, but I and the horses I ride vastly prefer the bit over the 7 different bitless systems I tried, even when I use the double bridle. The horses taught me what Phillipe Karl describes in the video.
All through this video I was going “YES!!!”, you’ve got it, that is how dressage horses should go under the rider.