Personally for me some examples are for 1 hour swim, disconnected from pump I need to have a 20 carb snack before and a small snack after. Just because I would have a bolus active and also full basal up until swimming. This is because if I was to use a temp basal prior I would be too high before swimming. If I was eating immediately before swimming I would only bolus 50% and not have a snack beforehand.
For a gym session I would put basal too 50% and if blood range was normal before hand would again have a 20 carb snack. If eating a meal within 2 hours after would need a reduced bolus. All individual and just a case of seeing what works best for you. I could maybe do further reductions but do not want to lose weight as it was a very big struggle to regain what I lost prior to being diagnosed type 1, 3 years ago, but, want to keep fit and active.