(Note: This answer was written before the example photo was visible.)
Why are your photos coming out blurry? Shutter speeds of 1/500 second or even faster are quite sufficient (in almost all normal situations) to avoid blur due to camera shake, and should also be able to stop the action, especially for jump shots, etc, where the player is not actually moving a huge amount at the precise moment of their shot. As a first guess, I wonder if the blur you are seeing is because you are missing focus? Of course, with a manual focus camera (and especially at large apertures), you have to take some care around accurate focusing.
Always though, my first thought is around exposure. Inadequately exposed photos is the easiest way to "fail" in photography in my opinion, and particularly with film photography. Shooting indoor sports is obviously not a super bright environment – the light levels might be somewhere around EV 7. If you are restricting yourself to 1/500 second exposures, then you are going to need wide apertures to get enough light to your film – especially with ISO 400 film. Indeed, I doubt your film is getting enough light. How are you metering the scenes? Just using the camera's built-in meter?
Personally, I love film photography, but I'd skip it for sports; I'd use my digital camera instead. But if you just want to experiment and have some fun, try using some black & white film – Ilford Delta 3200 or Kodak T-MAX 3200 – whichever you can find cheapest. It will be grainy, but with some care around focusing, you should definitely be able to get nice, interesting results.
Just to finish, I'm going to attach here an example sports photo I took on film – this was at the Olympic Games in Athens in 2004. I don't remember exact details, but I think this was possibly on ISO 100 film, probably using a 100/2.8 lens, and also probably shot at 1/500 second. The action is stopped by the fast shutter speed.

Alternatively, sometimes motion blur can be used as a feature of the photo.
