If you are a regular exerciser, try to use two pairs of trainers and rotate them, to give them chance to dry out and ‘breathe’. Another simple tip is to sprinkle some Bicarbonate of Soda inside each trainer. If possible, leave ideally for a couple of days to naturally deodorise the trainers.
Simply empty it out when the smell has gone. Bicarbonate of soda is gentle and doesn’t contain any phosphates, enzymes or bleach, so any residue won’t damage or stain your socks and won’t irritate your skin.