Swimming: increasing on my lap-length

From Rallarvegen

Due for another session with swimming again. This time I'd decided to increase the lengt of my lap to three lengths of 10m each. At first I managed fine and maintained a good technique. After some time I got tired and didn't manage to keep up my focus when it comes to technique. After 45 minutes I stopped the session. Next time I'll try with 1 minutes rest between each lap. This time I was down to around 40 seconds.  The important thing is to execute a good technique at all times-not the number of sets.

Technicals:
1. 25 laps of 30 m
Total distance: 750 m
Workout time: 45 minutes