I have a coming 4 yr old TB mare and she is constantly trying to yank the reins out of my hands at the trot. She yanks the reins hard enough that it rips them out of my hands. I have tried to hold the reins still to see if she gets over it and realizes that I'm not going to soften until she does and she nearly yanks me out of the saddle. I've also tried just sending her forward with my leg but she continues to yank. I had her in a simple full cheek snaffle and then switched her to a french link snaffle thinking maybe the single joint was having a bit of a nutcracker effect. Since changing the bit there hasn't been any improvement. I always try to have extremely soft hands but it seems like the only time she isn't yanking on the reins is when I have the reins so long that its impossible to yank them.
Any ideas as to why she is yanking the reins so much? Suggestions on how to stop it? As always, thanks in advance! :)