These are the definitions according to the ADS (American Driving Society) and can be seen in their rulebook:

EXTENDED TROT: The horse lengthens his stride to cover as much ground as possible as a result of greater impulsion from the hindquarters. The driver allows the horse, remaining "on the bit" without leaning on it, to lengthen its frame to gain ground, with the nose slightly in front of the vertical. The hind feet must clearly overtrack the prints made by the fore feet. The horse must remain in balance while maintaining the same tempo with steps of equal size. Going faster is not asked for, and is a severe fault.

STRONG TROT: This is a clear, but not excessive, increase in pace and lengthening of stride while remaining well balanced and showing appropriate lateral flexion on turns. Light contact to be maintained. Excessive speed will be penalized.

When I have done competitions, the strong trot has always been asked for in pleasure shows (ring classes) and breed classes and the extended trot has been asked for in dressage tests for combined driving or in dressage tests for pleasure shows.

When I teach one of our ponies to lengthen, I teach them to begin with on the ground.  Since voice communication is so important in driving, I will teach them this command while lunging.  I always use the same commands and use the same tones when teaching.  For example, for the trot I use 2 clucks and say "Doulton, trot on".  When I would like a canter, I kiss and say "up!".  I make sure my husband and I say the same thing using the same tone so we dont confuse the ponies.  When I ride them, I dont even need to use my legs to get them to move on or even slow down, I just use my commands and voice.  I also use a chirp to slow down...its amazing how quickly they pick up our commands and how well they work.

To get the extension, you can use trot poles.  Start with them spaced apart for a regular trot for a bit and lunge the pony over them so they are used to trotting over poles. Then stop lunging and push them out a little.  You can lunge your pony away from the spaced out poles and use you voice and whip (no hitting - just to be used for encouraging - keep it a little closer to their behind or give it a little snap in case they have blinkers on and cant see it) and once they have pushed on a little, direct your circle towards the poles and they will strech out over them.  Use a voice command so they learn when they hear it they will associate it with the extension.  I say "trot on" in an upward tone and all of our ponies will extend.  This may take a bit for them to understand, so dont get frustrated.  Don't worry, they will get it.

I hope this is clear and helps! Good luck!  Ask if you have any questions or if I've been unclear somewhere....

 Sorry these pics are so big, but the top one demonstrates an extended trot - still in a frame and extending (could be extending a little more though) and the pair picuture is a strong trot called in a pleasure class.  You can see that I have given the lines a little and the ponies are stretching and lengthing out.  I'm no means a proffesional but it does show you a difference of the trots...My avatar pic is also of a pony in a ring class doing a strong trot.  Its a harder angle to see though, but his nose is poked out a little and he is moving on.

-- Edited by Diamond_Jubilee on Monday 6th of June 2011 05:02:39 PM