Look in the side seam of your polyester sportswear. There should be a permanent tag that provides the specific fiber content as well as care instructions.
Follow the care instructions on that label. Seriously. That is what you need to do.
If you absolutely cannot find the label (look hard; if it is not in the side seam it might be elsewhere), then I would say machine wash with warm water and either hang to dry or tumble dry on a low heat setting. No fabric softener.