Florian,
I like that you are asking these kinds of questions that are likely on a lot of people's minds.
Paddling - set temp basal -40 to -60% 2 hrs prior to hitting the water. Temp setting depends on length and type of workout. During training I test before, during and after workouts but in competition I only test before and do so afterward if I remember. The adrenaline of racing plus the extra glucose I take in keeps my sugars relatively stable even though my effort is more intense than in training so I keep the same temp basal setting.
Running - Make sure I'm starting with a BG over 6 and just run. If under 6 then I'll pop a Dex tab or 2 then go. I should do a temp basal but runs tend to be spur of the moment and not planned. Plus running doesn't have as big an impact on lowering my BG as paddling does.
Weight Training - usually done in the morning, take a little extra with my breakfast bolus. Test before, during if I'm feeling funny and after. BG tends to go up.
Yoga - temp basal -20% when I remember a couple hours prior or reduce preworkout meal bolus slightly. Depending on the type and intensity of the yoga, usually BG remains stable or lowers slightly.
I've never experienced the 24 hr post exercise hypos that are common to a lot of people, could be due to my daily training but who knows!
In talking to people, the most common problem for folks is that they reduce their basal prior to exercise but they do it right at the time of exercise and still experience lows. Instead try reducing your basal of a couple hours before hand. We have to remember that the insulin we take right now isn't in it's peak action until 1.5 to 2 hrs from now. So by turning down your basal right at the time of exercise, you still have the insulin in your system from hours before. Turning it down 2 hrs before means that the reduced amount of insulin is at peak action by the time you start exercising. Experts out there ... please let me know if I'm on the wrong track here but this certainly works for me. I was introduced to this by my amazing team at my education centre after I was diagnosed and ran into troubles with lows while paddling.
See you on the water!
Leanne
Adventures in Paddling with Diabetes
http://www.leannestanley.com