"you don't want to ruin your breathing, do you?"

I have never understood this line from Lermontov when he approaches Vicki after rehearsal.

She's resting and a woman brings her water, but before she takes a sip he says, "ah ah ah... you don't want to ruin your breathing do you?" and she shakes her head and puts it down.

Can anyone who knows about dancing explain this? How does drinking water affect your breathing?? Or is this just a totally made up thing?