If not mistaken, thongs and G-strings are not encouraged for workouts. Apparently its easier to get UTI wearing thongs and G-strings for workouts as you sweat a lot and bacteria from your "back" is easier to infect your vajayjay through the cloth material...

But that was what I was told by a relative. A doctor told her about it after she got UTI. Never experienced it first hand since never used those for workouts.