KATIE SIGMUND felt the burn and showed off her bum after a sweaty workout.
The social media sensation is fast approaching par with fellow golfer Paige Spiranac in terms of her huge Instagram following.
And the influencer again hinted at her rigorous regime in the gym as she posed for a rear-view selfie in lycra-style shorts and a sports bra.
Katie produced a great twist and pout as she revealed her toned body.
The American, 21, looked pink-faced after her exercise session.
But that's nothing compared to her colourful look in an array of daring snaps posted online in bright red and blue outfits, as well as tiny bikinis.
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She chose a tiny scarlet one-piece for Halloween and a sweeping crimson dress for glamorous side-on shots, then switched to a gown of ocean blue for luxurious images while on holiday aside the Italian coast.
Katie is now up to 3.2million Instagram followers, just 800,000 behind former professional golf player Paige.
And the many ways she's revved up her battle to become the queen of swing on social media include cheeky pics on a dirtbike.
She teased admirers with an invitation to "Hop on!" as she prepared to roar off in the Californian desert.
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That time she wore a backless black number and thigh-high white boots.
But she was dressed in more traditional gym gear for her latest input on Instagram.
And as Katie turned to look down at her phone, she added the caption "Cutting szn" - followed by a heart.
That could be a reference to the phase - or season - when body-toners reduce calorie intake in the hope of losing body fat but retaining muscle.
If so, it suggests Katie pushes herself to the limit with her fitness regime.
