My first swim meet of the season with the K100D and the Tamron 28-300 non-DI lens. The meet started at 4pm and sunset is at 4:30, so lighting was to be a challenge. I played with ISO 1600 and 3200 and decided that for the lens I have, I really need to go with 3200. I stayed with a shutter priority of 1/125. You cannot use flash in the swim meets.
So, here is what you get if you don't have fast lenses. I will buy a fast lens before she graduates! (Two more years to go, so I feel confident in that statement).
And, then I played with a longer exposure (1 sec and .7 sec) with the camera resting on the railing.
So, yes the K100D can do indoor swim meets, but this is what you will get. I don't think I can do much better with my equipment. I will play with noise reduction next and see if I can clean these up and get a few nice ones.