Well, you can use a lower ISO, but only so long as you can still set the aperture and shutter speed you want. There is no point using a lower ISO if it means dropping your shutter speed to the point where you get a blurry picture from camera shake. In low light there is usually little you can do to keep the ISO low. Faster lenses, with a wider aperture, can help but that will give very shallow depth of field, which may not be suitable for what you are doing. IS lenses allow slower shutter speeds when handholding, but won't help with subject motion, so if you need a fast shutter speed to freeze subject motion, you are stuck with it.
There are just the three ways to adjust exposure, (ISO, aperture and shutter speed) you can set any of them where you like but they must add up to the correct exposure, so altering one means adjusting another in the opposite direction. Most of us aim to keep our ISO down as low as is practical, but it gets set as high as is needed to give suitable settings on the other two.
Don't try and get away with underexposing a little to use a lower ISO as that just makes the noise worse ehen you push the exposure back up. You are actually better off using a higher ISO and exposing to the right of the histogram (just google ETTR if you don't understand that) where noise is concerned.
After that, there is plenty of noise reduction software available that will reduce the noise significantly, with careful use.