One trick I learned when I had to keep a white medical uniform clean was to wash everything in cold water. Hot water actually cooks proteins and oils and makes them harder for the detergent action to remove. This seemed to work for all visible body fluids, I don't see why it wouldn't work for sweat as well. All I know is I'll leave sweaty stuff around for days before I get around to washing it, and I have no problems, my clothes smell fine when they come out of the dryer. And I'm talking soaking wet, 100 miles in 90 degrees weather sweaty.

I realize this is totally counter-intuitive, but try it before you start listing reasons why it can't be right.