I have a Malamute dog, so I run / walk her for at least an hour every evening, and occasionally take her sledding.
I don't tend to exercise when i'm high, nothing over 10, but i always cary some snacks with me, and have about half a pack of sweets on the way round.
It can be very unpredictable, as i could spend all the time running fast, encouraging her to pull, or i could spend it all trying to not get dragged off my feet as she plays with another dog.
Fruit juice is good, and i love banana's. It just depends so much on how intense your exercise is, what you're doing, and for how long.
When I do yoga i tend to have a little snack before, a couple of crackers and cheese, maybe a bag of crisps, and that's it. It's very relaxing and not very intense at all.
But i have no life, i do LARP events too... I know, sad and geeky lol.
An entire weekend of running around and generally having fun, i'll usually half / 3/4 my insulin doses, reduce my daytime lantus, and snack a little more as it can be very intensive.