Jennifer Lopez hit the gym for a workout with her trainer, David Kirsch


Talk about strong leg muscles!

Jennifer Lopez hit the gym Friday morning for a workout with trainer David Kirsch, and powered through a few “platypus walks.”

The singer, 48, did some power breathing as she performed the move — forwards AND backwards — while listening to Justin Timberlake‘s “Señorita.”

“@jlo this morning,” Kirsch posted on Instagram. “#Emilia [Kirsch’s daughter] making sure her #platypuswalks were on point.”

Kirsch added a few hashtags to point out that J.Lo was “#bootilicious” and “#killingit.”

Lopez is seriously dedicated to fitness. Lately, the superstar has been hitting the gym with boyfriend Alex Rodriguez, but she also loves working with trainers like Kirsch and Tracy Anderson, who she typically sees to four to five times a week.

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“With her busy schedule, that’s a lot,” Anderson previously told PEOPLE. “It can be anywhere from 30 minutes – if her kids need her for something, because she’s always there for them – to an hour or hour and a half.”

And she started boxing again last year for her show, Shades of Blue.

“I always liked it,” Lopez said. “It’s very hard, but I did pick it up again. It’s always been a good workout.”