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I found this was happening because I was overloading the washing machine and using too much detergent... I now make sure I do two smaller loads instead of one big one and use a bit less than the recommended dose of laundry detergent. Anything that is extra stinky (like gym gear) I also add a cupful of eucalyptus oil to the wash.
My hubby has this problem with his gym gear even if put straight in the wash. He recently soaked them for half an hour in water and vinegar then washed them as normal they have come out smelling so much cleaner and he doesnt get the horrid smell as soon as he starts working out in them
I rub the arm pits of the tops with sard wonder soap then wash as normal and line dry in the sun. Sometimes it works, sometimes it doesn't.
I use cloudy ammonia in a hot wash. I can't say for sure if it helps bo smells but I definitely haven't noticed that smell since I've been using it.
Try sport detergent. I do hubby's undershirts amd my tank tops and all the kids gym and sports unis