Whether you were drenched after a workout or barely worked up a sweat, you might notice one thing when you get home: your activewear reeks.
While you might put this down to body odour, there's a good reason your gym kit smells particularly bad, according to BBC's Trust Me, I'm a Doctor. Body odour isn't caused directly by sweat but by bacteria living on the surface of the skin near sweat glands.
The tv show recruited a group of volunteers and had them take part in two high-intensity spin classes. In one group, they wore 100 per cent cotton, while the next group wore 100 per cent polyester. Both groups avoided using deodorant.
Analysts swabbed their armpits before and after as well as examining their activewear.
The samples were looked at by Professor Andrew McBain and Doctor Gavin Humphreys from the University of Manchester. Nearly 300 strains of bacteria were present on their participants' armpits.
Typically, there are two types of bacterias linked to body odour: the more common Straphylococci and Corynebacteria which produces fouler smells. Men are more prone to latter.
When the two researchers looked at the effects of the fabric on our armpit bacteria, they found not only no differences but the bacteria wasn't ending up on the activewear either.
The team concluded that rather than the bacteria on our skin causing the odour, it was actually the fabric causing the foul smell.
One explanation suggests that fabrics like cotton absorb moisture while synthetic does not, suggests Dr Rachel McQueen from the University of Alberta in Canada. She proposes that bacteria gets 'trapped' inside fibres and don't leave the body. Meanwhile, synthetic fibres attract oils from our sweat, mixing with bacteria on our skin causing odour.
Meanwhile, previous research from the University of Ghent found that the bacteria, Micrococcus, grew in greater numbers on synthetic as opposed to cotton.
So, next time you're planning a date that involves a little exercise, maybe stick away from the synthetic kit if you don't want to put if you're potential partner.