Baby One More Time! Britney Spears does grueling crunches as she preps for Vegas residency

She is focused on fitness as she's set to return to her Las Vegas residency at Planet Hollywood's Axis Arena on March 22.

And on Monday Britney Spears shared a 15-second video on Instagram as her trainer put her through a grueling work out.

The 35-year-old was concentrating on her abs as she completed 15 crunches on a small box, which elevated her body above ground level and meant she could never lie back for a sneaky rest.

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So feisty: On Monday Britney Spears shared a 15-second video on Instagram as her trainer put her through a grueling work out

So feisty: On Monday Britney Spears shared a 15-second video on Instagram as her trainer put her through a grueling work out

At one point, her trainer touched her washboard tummy to correct her style as James Brown's I Feel Good played in the background.

The Toxic hitmaker showed off her toned and tanned tummy and muscled legs in a yellow bra top and black shorts that she rolled up to reveal more skin.

Britney smoothed her blonde tresses back into a pony tail, secured with a clasp.

She captioned the video: 'Just another humble workout post' and added three smiley emojis. 

Tough task: The 35-year-old hitmaker was concentrating on her abs ahead of her return to Las Vegas for her Pieces Of Me residency at Planet Hollywood's Axis arena 

Tough task: The 35-year-old hitmaker was concentrating on her abs ahead of her return to Las Vegas for her Pieces Of Me residency at Planet Hollywood's Axis arena 

Do it right: At one point, her trainer touched her washboard tummy to correct her style as James Brown's I Feel Good played in the background

Do it right: At one point, her trainer touched her washboard tummy to correct her style as James Brown's I Feel Good played in the background

 With just three more months to run, she is coming to the end of her Britney: Piece Of Me residency at Axis.

Ticket sales from the show have now topped $100 million, Billboard reported on Friday, citing numbers registered on its Boxscore service by show producer Caesars Entertainment.

Since the debut performance on December  27, 2013, some 710,418 fans have paid to see 197 shows.

Could it be any harder: The hitmaker did her crunches on a small box, which elevated her body above ground level and meant she couldn't lie back for a sneaky rest

Could it be any harder: The hitmaker did her crunches on a small box, which elevated her body above ground level and meant she couldn't lie back for a sneaky rest

Tightening those tummy muscless: She captioned the video, 'Just another humble workout post' and added three smiley emojis

Tightening those tummy muscless: She captioned the video, 'Just another humble workout post' and added three smiley emojis

Britney was originally signed to play through 2015 but the hugely successful run was extended,

With less than three months remaining, Britney: Piece of Me is booked for nine more performances in March and April, and nine nights in May.

Her last concert in the Axis is set for Saturday, May 20.

Huge money earner: Ticket sales from Britney's Pieces Of Me residency have now topped $100 million since the show kicked off on December 27, 2013, according to Billboard

Huge money earner: Ticket sales from Britney's Pieces Of Me residency have now topped $100 million since the show kicked off on December 27, 2013, according to Billboard

 

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