My trainer mentioned trying a running martingale on my jumper who sometimes likes to throw her head up and get all hollowed out, just as a training aid. She told me to get the martingale as well as a breastplate, but since I've never used one before on my mare and it may not work, I don't want to spend an arm and a leg buying new items. I noticed some (like this one) come with the neck strap, would I really need to get a breastplate to use instead?
What are the advantages/disadvantages to having one?
Now, I may be completely wrong about this since I don't ride english and don't ever use things like this, but I believe the entire purpose of using a breastplate/neck strap with a martingale was to keep the rest of it restrained up close to their body so that they can't get a leg through it if they drop their head.
If your saddle fits well and you don't need a breastplate, then I can't see any reason why the martingale with the neck strap wouldn't work just fine.
A running martingale with just a neckstrap is fine If you don't need to stabilize the saddle. I usually use a breastplate when jumping, especially bigger jumps, for the help in keeping the saddle in place.