Hi, I found I had to test alot to see what effect different types of exercise have on my bg levels. For example swimming always brings my levels down immediately, so I eat around 20g carbs before swimming (something like a banana). Rock climbing and anaerobic sports on the other hand generally make my levels rise for a while, due to the adrenaline I think, and then drop over the next few hours.
I think it's always best to test before, after an hour or so depending on the sport, after and then an hour or so after. Over time you'll know which sports will affect your levels in which way and you can test less perhaps. Different times of day may also effect your levels when exercising, I find running in the mornings makes me go higher than other times of the day.
I personally wouldn't have a meal with insulin before any sports, i'm fairly insulin sensitive and wouldn't want it in my system in case I went low while exercising. I tend to have a snack before exercising if I need to, e.g swimming, and then eat a proper meal with insulin after.
You'll find out what works best for you over time, everyone's different. The runsweet website's pretty good for sepecific sports info I agree.