I am an amateur swimmer and have started swimming in the pool 2.5 years ago. I enjoy all strokes and swim IM. This last year i have trained hard and got to this time a week ago 2:41 200m im (25m pool). What would it take to catch ~ 2:25 ? What are the advanced techniques for an IM-er? I get a bit tired in the first 50m of butterfly and suffer a bit the backstroke exhaling part underwater.
