I wash all my whites including underwear and socks in the sanitary wash cycle. Have also washed towels and sheets in sanitary during flu season. No problems with any elastic. I have white socks that are over 3 years old and the elastic is fine.
It's chlorine that damages the rubber in elastic things.

Real rubber elastic may do fine in hot temps but anything with Lycra or other synthetic stretchy stuff won't last long.

Thanks, y'all. That's exactly what I needed to know. It sounds like socks and underwear are probably fine in the higher temps, but sports bras are a no-go.

Don't forget to consider dryer temps, also. Dryers can get even hotter than this depending upon cycle chosen.

Watch out for synthetic blends in socks. I use sanitize with Oxyclean to really get whites white. The water gets hotter and it takes so long that the Oxyclean does its job.

It's true about dryers getting hotter. More damage to clothes come from the dryer and not the washer. Hot water doesn't really shrink clothes but a hot dryer will.