Sweat stained clothes

Even after washing, my work out clothes remain smelly in the pit area. No problem because that’s what work out clothes are for. Except I have a t shirt from a local establishment that recently closed so I have no chance of replacing it. I’d really like to add it back into my regular wardrobe but the smell is noticeable (at least to me). What can I do to get rid of the smell? The shirt is 100% polyester if that matters. And going forward is there anything I should be doing with respect to my laundry to stop this problem?