In the case of my friends horse, he starts out stiff and almost 'off' as he is a teenager with a history of lameness. We have his hoof angles perfect, his hocks and stifles well greased, and all the best supplements that are on the market on board. I know that in 60 meters or so he will warm out of it, and I have to just stay steady with heels low, and back strong and wait for the gentleman to get his kinks out. Almost always he comes into the work with enthusiasm and collection in a light, kind manner.
At the horse show today my horse came out a little hot and I almost changed my warm up to put him into collection from the start (cuz he was 'up'). His mouth was busy and I could hear the bits clanking around and his neck was up. But, this little voice inside me reminded me to pretend that we were on the dirt road on our morning hack and to warm up with a low poll (or wherever it wanted to be) and a strong back and a low heel. Then when the time was right we re-created the relaxed workout that we have at home and in the end the tension was gone.
I may not win the blue ribbon tomorrow but I will know that it wasn't because I took a short cut and compromised the trust that I have built in this horse.