Zac Efron, 33, shows off his bulging biceps in a loose tank top

Zac Efron shows off his bulging biceps in a tank top while signing a fan’s High School Musical DVD in the Australian outback

Zac Efron is arguably one of the fittest actors in Hollywood.

So it was no surprise to see the Baywatch hunk’s bulging biceps on full display in a sporty tank top last week.

The 33-year-old’s incredible arms were hard to miss as he signed a High School Musical DVD for a fan at the Flinders Ranges National Park in South Australia.

Muscle man! Zac Efron showed off his incredible biceps in a sporty tank top in the South Australian outback last week 

Zac has been busy filming the Stan Original movie Gold in the outback location.

He looked more than happy to sign the DVD and pose for a selfie with the loyal fan, who later gushed about the experience in an Instagram post.

‘Today I met the man who I’ve looked up to since I was five years old. Once a Wildcat, always a Wildcat. Love you forever,’ the fan wrote.

Fan service: The 33-year-old was more than happy to sign a DVD and pose for a selfie with a fan

Fan service: The 33-year-old was more than happy to sign a DVD and pose for a selfie with a fan

Judging by Zac’s sporty attire, comprising shorts, sneakers and a tank top, the star has been keeping fit on the set of his latest film.

His current physical appearance is worlds away from a photo Zac shared on Instagram last July, in which he posed shirtless alongside Jim Carrey.

While still looking muscular, Zac’s arms were less defined than they are now, which proves he has clearly been ramping up his fitness routine Down Under.

Before: His current physical appearance is worlds away from a photo Zac shared on Instagram last July, in which he posed shirtless alongside Jim Carrey (pictured)

After: Judging by Zac's sporty attire, comprising shorts, sneakers and a tank top, the star has been keeping fit on the set of his latest film

Before and after: His current physical appearance (right) is worlds away from a photo Zac shared on Instagram last July (left), in which he posed shirtless alongside Jim Carrey

In another photo, taken in October 2019, Zac posed shirtless in a sauna, and looked remarkably less defined than he does these days.

The High School Musical star’s physique has changed a lot over the years.

He was potentially at his most ripped in the 2017 movie Baywatch – but even for other roles, Zac has always maintained a chiselled look.

He has spoken out about his sometimes brutal fitness regimes in the past.

Throwback: In another photo, taken in October 2019, Zac posed shirtless in a sauna, and looked remarkably less defined than he does these days

Throwback: In another photo, taken in October 2019, Zac posed shirtless in a sauna, and looked remarkably less defined than he does these days

In 2012, he confirmed he’d trained for ‘five days a week for four months’ and ate a protein-rich breakfast every morning for his role in The Lucky One.

‘A shake and, you know, an eight-egg omelette,’ he told Men’s Health magazine. ‘I got used to it at the time, but I wouldn’t recommend it.

‘It’s not practical to do for a long period of time. You feel this debilitating soreness. This kind of stuff, going golfing, you can’t do.’

Gold will be airing on Stan in 2021.  

Training: Zac was in peak physical condition on the set of Bad Neighbors in 2014

Training: Zac was in peak physical condition on the set of Bad Neighbors in 2014