Two Swimming Questions

Hey, I was like this as well when I started, here's some things that worked for me. Breathe every 2 strokes as opposed to 3. Over time this will become very easy and you can switch to 3 strokes breathing at this point. Try and slow down your pace just a bit, even though it may feel slow, when you are starting out it takes your body awhile to get accustomed to what is a moderate pace. Hope this helps,
Cheers,
Mike

A good 100m time is difficult to define.

It all depends on the ability level you're looking at. For an Olympian, 48-low is a good 100m time. My best time before I quit swimming was :52. For a pro-triathlete, holding about 1:10-1:13 for the 1500m swim leg of the Tri will get you FOP. For an amateur triathlete, 1:30ish will most likely get you to the FOP, and 1:40-1:50 is MOP (By the way, FOP = Front of Pack, MOP = Middle of pack).

It all comes down to perspective!

With regards to the CO2 buildup in the lungs, are you exhaling while your face/mouth is underwater? Try and consciously exhale and blow bubbles while your face is in, either in one short burst right before you breathe, or continuously.

That said, what is your breathing pattern? If you're trying to breathe every 3, maybe taper off to switching between 2 and 3 for a while. There is also nothing really wrong with breathing every 2, despite what some may tell you, since at this point, maximal oxygen intake is your priority.

I hope this helps somewhat!
Derek

Thanks folks! Both responses help a lot!