EDINA, Minn. (WCCO) — On any given day, the water aerobics classes at the Southdale YMCA are packed.

About 40 members were in the pool Monday afternoon, grooving to the music, when a 73-year-old woman suddenly slumped over in the water.

READ MORE: How Feds Are Working To Crack Down On Crimes Committed With Illegal Firearms

Aerobics instructor Natalie Martin was teaching the class and began chest compressions and CPR immediately, along with two lifeguards.

“The AED came after about one round of compressions and some rescue breathing and thank goodness for that AED,” said Martin.

After using the device, the woman’s heart started beating again.

“To know that we had a successful outcome and that she is breathing today and that I might get to see her again is emotionally overwhelming,” said Martin.

Most of the YMCA staff has to go through CPR, oxygen, and AED training, so they are prepared for incidents like this.

READ MORE: House Ethics Complaint Against Rep. John Thompson Dismissed After He Agrees To Apologize

“We always talk about the unexpected, but this is what we are trained for, and this is what we get ready for,” said Southdale YMCA Executive Director Greg Hanks.

A heart emergency can strike anyone at any time.

“This woman is very fit, works out here all the time. We all know her. Nobody would have expected it,” said Director of Healthy Living Roxy Kline.

It’s important people stay in tune with their bodies and look out for these warning signs.

“Any type of dizziness, excessive unexpected sweating, heart palpitations, any pain in the chest, or lightheadedness,” said Kline.

YMCA staff says this marks just the second time this year the AED device has been used.

MORE NEWS: Eviction Moratorium Update: Without An Extension, What Happens To Renters After July 31?

As for the woman who was rescued from the pool, she is still recovering in the hospital, as of Tuesday afternoon.