Britney Spears Is ‘Mentally And Physically Ready’ For Las Vegas Show, Says Trainer

Britney Spears is ready to become a Sin City headliner -- stepping up gym workouts, so she can slip into those ab-baring costumes for her new residency at Planet Hollywood Resort & Casino in Las Vegas, RadarOnline.com has learned.

Speaking exclusively to Radar, her trainer is dishing all the details about the "Perfume" singer's tummy-toning workout and how she is preparing for her show, Britney: Piece of Me.

"She is working as hard as she can, and it is paying off," the Grammy winner's trainer Tony Martinez tells Radar. "She's using all her energy right now to get ready for her 90 minute Las Vegas show."

Spears is sweating through grueling 40-minute workouts about four days a week.

"My workout motto is work out smarter, not longer," the celebrity trainer reveals.

"There's no need to run on the treadmill for two hours. I've shown her ways to sculpt her body that take less than 20 minutes. Now she's loving these quick workouts,” he said of the “Oops, I Did It Again” singer.

The pop princess is focusing on high-intensity intervals, along with cardio, which includes sprints, jumping rope, basketball drills and boxing.

Seeing the slimming results, the mother-of-two isn’t complaining.

“She wants to be in the best shape possible, and she is very happy with her body right now,” Martinez reveals.

And despite suffering a psychological breakdown on 2008, Spears is “better than ever,” he claims.