All puffed out! Make-up free Kesha needs a breather after working up a sweat on grueling hike with boyfriend Brad Ashenfelter

It's been three months since her last world tour but Kesha is making sure to keep in shape.

The pop singer was spotted working up a sweat with boyfriend Brad Ashenfelter on an exhausting hike through the Hollywood Hills on Sunday.

The 28-year-old singer went makeup-free for an intense workout session and seemed as though she needed to stop for a breather along the way.

Gasping! Kesha, 28, went makeup-free for an intense workout session in the Hollywood Hills on Sunday and seemed as though she needed to stop for a breather along the way

Gasping! Kesha, 28, went makeup-free for an intense workout session in the Hollywood Hills on Sunday and seemed as though she needed to stop for a breather along the way

Uphill battle! The singer and songwriter was joined her boyfriend, Brad Ashenfelter on the exhausting hike

Uphill battle! The singer and songwriter was joined her boyfriend, Brad Ashenfelter on the exhausting hike

Looking flushed while working up a sweat, Kesha and her beau coordinated their exercise gear in all black wardrobes. 

The Tik Tok hit-maker added a pop of colour to her look with pale pink trainers and swept her long blonde hair back into a high ponytail.

Kesha and Brad were first linked in April 2014, a month after she left rehab after being treated for eating disorders.

Pale and perspiring: Looking flushed while working up a sweat, Kesha and her beau coordinated their exercise gear in all black wardrobes

Pale and perspiring: Looking flushed while working up a sweat, Kesha and her beau coordinated their exercise gear in all black wardrobes

And although looking happy and healthy, Kesha has had a tough time of late.

The award-winning singer is currently locked in a legal battle to try to be able to record again without her producer, Dr. Luke to whom she is bound through her Sony Music contract. 

Dr. Luke, real name Luke Gottwald, allegedly drugged and raped her, and threatened to take away her publishing rights. 

The pair have been battling it out in the courts for a year over the claims and contractual disputes and Sony does not want Kesha recording with anyone else until the disputes are sorted.

Legal woes: The award-winning singer is currently locked in a legal battle to try to be able to record again without her producer, Dr. Luke to whom she is bound through her Sony Music contract

Legal woes: The award-winning singer is currently locked in a legal battle to try to be able to record again without her producer, Dr. Luke to whom she is bound through her Sony Music contract

In late October, in a new injunction, Kesha claimed her career has been on a hiatus and will be 'effectively over' if she is not permitted to resume recording immediately, Buzzfeed reported.

The lawsuit states Kesha is at 'a grave risk of irreparable harm if she continues to be prevented from working'.

'Kesha Rose Sebert wants nothing more than to be able to record an album,' the court document says.

'Her only condition is that she be allowed to record with a record label that is not affiliated with someone who has emotionally and sexually abused her.'