0_Apprentice
I love to swim, I go to the lake all the time when I can, Do you know anything about swimming? 
1_Wizard
It's a rather low-impact exercise activity compared to running or lifting weights, and it's used often in physical rehab because of that.
0_Apprentice
Oh yes I have heard of that, Doesnt swimming give you more excersize though? How many calories do you burn?
1_Wizard
It is great exercise, and it's quite a popular recreational activity too. Generally if you swim for an hour (not just leisurely but seriously) you can burn about 600 calories.
0_Apprentice
That is a lot wow, Ive been wanting to get into competitive swimming, How fast do Olympic swimmers go anyways? 
1_Wizard
In international competitions and the Olympics, you can expect the average pro swimmer to swim about 5.3 mph, which is pretty fast in water!