And more and more classes are incorporating them.
Bungees allow you to add your own body weight and effort into a move.
Some bungees offer more resistance than others, making the exercises more challenging.
And you'll find bungees in a variety of classes.
At Chelsea Piers, trainers are using a TRX Rip training device in their class.
Each person grabs a weighted bar which is attached to the base with a bungee cord.
"Any exercise you do you're going to feel the resistance of the bungee cord as you rotate through the abdominal area," said Viveca Williams, who teachers jump strike class at Chelsea Piers.
She guides us through the Samurai, the hockey shot, the Rip 90 press, and a paddling stroke.
There's also interval training on trampolines to get the heart rate up.
But the bungees is where the strength training comes in.
On the graceful end of the bungee spectrum, there's ballet bungee.
Here it's ballet without a bar, but bungees instead, which offer resistance.
And that offers a challenge, even when you're doing plies.
You feel it especially in your arms, and who wouldn't want dancer arms?
You don't have to have studied ballet to follow along.
And surprisingly your heart rate does go up. There's no relief, even when you curtsy.
"You walk better, you're able to stand taller, and who doesn't want to stand a few inches taller," said Rachael Piskin, a former ballerina with the New York City Ballet.