If it is a body odor and sweat issue I would personally try ammonia. I have had great results with removal of sweat stains and odors with it. Of course bleach will kill off the bacteria, but not remove the odor causing issue. If you are using bleach, the garment will likely withstand a hot wash with about 1/4 of ammonia.

This is what happens when fabrics have built up body oils. Smells fine out of the wash but as soon as any moisture hits it boom.

What water temp are you using to wash them in? Whatwasher do you have?

As for fixing them...try a good detergent Tide or Mexican Ariel POWDERS (not what's sold in american stores you need to go to a Mexican grocery store) and as Dorey says add Ammonia. Hot water or at least very very warm otherwise your going to be stuck with the muck.

I fill the machine and soak in Oxyclean unscented. (It doesn't harm colors). Then finish the wash and be sure to get the clothes right into the dryer, don't let them sit in the washer. I dry my cottons for about 5-10 min, then hang to dry. I think this will solve your problem. I find if I let the clothes sit at all before drying, the water seems to sour them (I have well water), so that they smell when they get wet again. The same thing happens to my towels if I don't bleach them and/or dry quickly after washing them.

We have plenty of stinky workout wear in my house and never have this issue. I always wash using a premium liquid detergent or pod plus a dose of oxygen bleach and always wash workout wear in hot water, despite what the care instructions say.