Experts have had their say on a debate that often puzzles gymgoers.

How often should you wash your exercise gear?

And Aussie researchers say they don’t agree with advice from Europeans.

Earlier this year, the French government caused a stir with advice about how often you should wash your clothes to save the planet.

The Agency for Ecological Transition (ADEME) said people were washing clothes too often.

Jeans should be worn a hefty 30 times, it said.

Bras, meanwhile, could be worn seven times before going in the wash.

For sports clothes, it recommended a lengthy three wears before throwing them in the laundry basket.

But now an RMIT expert explains why Aussies might need to wash more frequently.

Dr Carolina Quintero Rodriguez, senior lecturer in fashion enterprise said while the recommendation stemmed from “legitimate environmental concerns” things had changed.

“In the past, exercise clothing was usually made from natural fibres (mainly cotton),” Rodriguez said.

“Now, it’s mostly made of high-performance synthetic fabrics.

“These are designed to manage moisture, regulate temperature, improve breathability and control odour.

“However, research has shown this kind of exercise clothing, particularly synthetic fabrics, can harbour significant amounts of bacteria after just one use.”

She says it was best to throw them in the washer after each use but a more eco-friendly cold wash was fine.

However, if you’re wearing cotton, you can probably follow those French rules.

“Natural fibres such as cotton multiply fewer odour-causing bacteria than synthetics. So if you wear these fabrics to exercise in, they may last a few wears before needing a wash,” she said.

And if you’re only walking or doing yoga, you can probably get more wears out of your outfits.

But it’s true that clothes smell.

“There is a direct correlation between how much bacteria is present and how intense the smell is,” she said.

Bras and underwear, as well as socks, should go straight in the laundry, the expert said.