'Don't lose sight': marathon champ's legacy warning

Two-time Olympian Izzi Batt-Doyle is riding running's remarkable surge in the country, but the self-confessed purist wonders if it's become "too trendy" for its own good.

Four years after only about 5000 people crossed the finish line, 40,000 people will run the Sydney Marathon - and another 83,000 missed out in the ballot.

Twice a Games athlete on the track over 5000m, Batt-Doyle wants to run the marathon at the LA Olympics in 2028 and will pace the elite women's field on Sunday for the first half of their picturesque 42.2km journey.

An ambassador for one of the race's major sponsors, Asics, Batt-Doyle owns a running shop and cafe in Adelaide and has a first-class honours degree in psychology.

"You can't just rock up to Collingwood's training and join in, but we can run with people of all different levels on the same track. I run with my mum and recreational runners.

Sydney's marathon started in 2001 as a legacy event following the city's Games and hovered around 1000 participants for several years.

Now it offers $30,000 to the first Australian male and female across the line and has attracted current and former Olympic and world champions.

Its rise - Sydney earned major status alongside seven other marathons around the world last year - sums up the country's relationship with running.

But Batt-Doyle's customers and running buddies also speak of the challenges that have come with that.

"You have to plan so far in advance if you want to enter a race, and it feels like if you're not doing (social media) content you don't have a space in the running world," she said.

"At one level running's losing its purity a bit, because it's so cool and buzzy."

Batt-Doyle readily admits she's leaned into it with her own YouTube channel and social posts.

"It's helped my profile, I've got more sponsors, but you have to lean into it and we're trying to add an elite perspective," she said.

"To be honest, I got a bit sick of seeing influencers telling people what to do and thought, 'I can do that'."