Most indoor basketball places and gymnasiums have horrible lighting. The one at my school is aweful. I use 800 ASA film without flash or 400ASA with a flash (sometimes making annoying shadows) both with my lens at f/3.5.
With the 400 speed I get just slightly dark images. not horribly dark, just darker than id like at 1/125.
With 800 I get 1/250 of a second. (my flash sync is only 1/125 on my camera) The drawback is that I get I lot of grain in some of the pictures.
your best option is to push your cameras limits. use the fastest shutter speed (absolute SLOWEST being 1/125. any slower youll get negative amounts of motion blurr. at 1/125 I get some blurr but it looks pretty cool. at 1/250 I get almost none, At 1/500 you hardly get any at all.
If you like stopping action, than do what it takes to get to 1/500. Otherwise use 1/250 where its not in most of the picture or if you really like the look of action use 1/125 and itll be in most, but not all of the pictures.
If your close enough, the use of a flash is very very usefull for sports if you can get close. I use a 35-105mm f/3.5 lens sitting front row at my gym. I move myself when the teams switch sides.
Have fun shooting!