Ted, when he did his tendon, Had them on about 22 hours a day, He had the woof boot ice boots, Id put on pack on before i left the yard in the morning, Take it off as soon as I arrived that evening, and put the other on just as i was leaving,
i've got some instant ice packs - i was going to wrap them in tea towels and put them on after washing off after xc. so about 15 mins would be ok.... great thanks.
20 mins and then they usually loose their coldness anyway. Also never put ice packs directly onto the skin as they can cause freezeburns unless the pack states that it is safe to do so.
IMO the only reason to hose at all is directly after injury as a first aid measure. Unless you can get the leg totally dry after putting cold water on warm skin you are actually encouraging heat back into the area very quickly. Not only do the skin cappilaries open wide to allow blood flow to the area, the water left in the hair also starts to heat up. Because of that ice boots would be a better choice if they were genuinely a need for cooling off.
I know some people do routinely hose and bandage after strenuous exercise but whether thats scientifically proved to be necessary I dont know.
I used an aerborn 'cool gaiter' for my lad when he had a tendon injury, and swear by it. You can put it on for 20mins, every 2 hrs, when the injury is new.
It stores in the freezer and won't burn the leg even if left on for longer than that, as it naturally warms up after the allowed time.
Cost around £12 I think?
Good luck!