Tim Robards showed off his fit physique as he attended a Sydney event sponsored by Gatorade on Tuesday.

The SAS Australia star, 41, revealed his muscular arms in a black singlet at the launch of Australia's first ever step count currency store in Sydney.

He completed his ensemble with black shorts, white runners and had a towel draped over his shoulders.

The former reality star then headed outside and smashed some steps on an outdoor treadmill.

The Gatorade Sweat Exchange offers $150k worth of rewards in exchange for sweat, where participants can claim Peloton equipment, Garmen watches and a trip to New York.

Tim was at the event to promote the competition, which will be open until 8pm AEDT on Boxing Day.

The sighting comes after Tim's wife Anna Heinrich showed off her growing baby bump on Saturday as she posed for a mirror selfie.

Anna, 36, lifted her white shirt as she posed in a yellow outfit and said she is struggling to fit into her pants.

'Didn't quite fit into my pants,' she captioned the post.

Tim and Anna announced they were expecting their second child in September, with an adorable clip of their eldest daughter Elle announcing the family news.

'My mummy going to get baby soon,' Elle said, with a balloon stuffed down her top.

Tim and Anna, who married in Italy in 2018, also confirmed their joyous news in the caption.

'Turns out Elle was right. Bringing another little rascal into the world 2024,' the pair wrote.

In October, the couple hosted a gender reveal party in the backyard of their $6million mansion in Sydney's Dover Heights.

The couple and their daughter Elle, two, joined with their extended family for the celebration, including Anna's sister Andrea.

Sharing a video of themselves popping a pink confetti gun, the overjoyed couple wrote: 'I think Elle is psychic...turns out she was right again and is getting a sister.'

Chiropractor Tim fell in love with lawyer Anna on the first season of the Bachelor a decade ago.