Many of you have asked me to give some breaststroke workout advice in your comments, so here it is.
Below you will find a few tips for your breaststroke 50s and 100s and I am sure it could come handy for longer events as well.
First, keep in mind that breaststroke is a combination of leg power with good timing, so focus on this in your workout (apart from strengthening your arms and improving breathing).
The best and fastest way to improve in your swimming is to make your technique better which will allow you to move through water with less energy.
Here are some breaststroke sets that might help you with your kick and arms
. Note: You should not do only breaststroke in your practice as that can be quite stressful on your knees, so put other strokes in between.
Focus on extending your arms very fast forward when you bring them together and do not let your head go down under the water.
Hold a medicine ball above your head while kicking breaststroke or eggbeater (this is best done in a pair where you can throw the ball to each other)
Take two pulls after each turn (if too tough to start with, feel free to alternate two and one or decrease the distance)
Find a wall and align yourself vertically against it, feet down.
Then put your arms either above your head or behind your back and start kicking short breast kicks.
The idea here is that you should stay vertical, pressing your chest to the wall, but your knees should hardly touch the wall.
This will help you to be more streamlined and it will stop you from bringing your knees too far underneath your chest when you swim.
Arms are in a streamline, heels go down almost to your butt.
Knees are NOT coming out of the water and pelvis stays at the surface.
Should have the same effect as the wall kick above.
Obviously, all these sets/intervals should be adjusted to your own liking/level.
To get a good power in your legs a weight room work is always suggested :).
For helping your breathing, you can use Power Breathe (just 2 times 30 breathes a day and you'll see a difference within a week).
Go out there and have fun swimming.