EXCLUSIVE: How Britney Spears shed the pounds and got her body back for Vegas residency with the help of celeb trainer Tony Martinez

Britney Spears, Pink, and Janet Jackson have triumphed over their yo-yoing weight problems thanks to personal trainer Tony Martinez.

Tony helped rock star and mom of two Pink get back into shape by using a skateboard in her workouts.

And he helped 33-year-old Britney regain her youthful toned look ahead of her hugely successful residency at the Planet Hollywood in Las Vegas.

Before that the 47 year old LA native helped Janet Jackson stun millions with her controversial 2004 'Nipplegate' half-time performance at the Super Bowl alongside Justin Timberlake.

His 'workout smarter, not longer' philosophy also helped Janet lose an incredible 60lbs in four months to appear on front cover of Shape magazine.

But out of of the three icons, Tony says Pink is without doubt his 'most competitive' client, saying: 'I call her an athlete entertainer.

'She's very athletic. We would do stuff on a skateboard because she use to be a skateboarder, she loves that. She's a good athlete.

'I'd also make her do fun stuff on a trampoline afterwards, then get back on the skateboard.

'She was on the skateboard doing lateral raises, it was amazing!

'I have to be creative to keep her on her toes.'

Two years ago Tony prepared Britney for her ongoing Las Vegas residency which kicked off December 2013.

Britney wanted to be as toned as possible for her Vegas shows, which she accomplished with 'intense' workouts three to four times a week for 40 minutes.

Tony revealed: 'She loves all core workouts. She's a very tenacious women. She wants to get it done and get it done right.'

What are some of Britney's favourite core exercises? Tony explained: 'We use my core discs.

'Core discs are little circle things that I had made up for my product and we use those for a lot of ab workouts. We use those for mountain climbers, will do a barrel role tuck in where you turn around all the way over and then you bring your knees in. So really functional exercises that she likes, and she's like, "I really feel this."'

Tony also helped the singer clean up her diet to compensate with her grueling workouts.