Cotton tee workout gear has never really gone away, it just got buried under two decades of polyester marketing and the quiet shame of being told natural fibres were for amateurs. If you have spent any time running trails, grinding out hill reps, or simply trying to feel human on a Tuesday morning jog, you will know the particular misery of a synthetic shirt that has absorbed one too many long sessions and now smells like a wet dog in a chemical plant. There is a better option, and it has been folded at the back of your drawer this whole time.
How Synthetics Took Over the Changing Room
The takeover was swift and, at the time, convincing. Nike rolled out Dri-Fit in 1991. Under Armour was founded in 1996 by a former college football player who could not stand his sweat-logged cotton practice shirts. By the early 2000s, these fabrics had filtered from elite athletes down to every gymgoer, and cotton was suddenly considered a performance liability. The bloke at the local bike shop would tell you cotton was rotten. The soft-focus ads agreed. And so did most of us, for a while.
The trouble is, the synthetic revolution delivered mixed results in practice. Those technical shirts felt stiff and scratchy. After half a dozen wears they held a stench that no amount of soaking in distilled vinegar could shift. On long runs, the friction alone became its own problem. Yet people wore them dutifully, for years, because that was simply what you were supposed to wear when you exercised.
The Science Behind Cotton Tee Workout Gear
It turns out there is solid research to back up what your nose has probably already worked out. A study at Ghent University, conducted independently from the cotton industry, collected T-shirts from volunteers after an hour-long spinning class and had a panel of trained sniffers assess them the next day. The polyester shirts came out significantly more foul, rated as mustier, sourer, and more ammonia-like. Cotton shirts performed considerably better.
The reason, according to Chris Callewaert, the microbiologist behind the study who goes by the name Dr. Armpit, comes down to chemistry. Polyester repels water and clings to oil, and the oily residue in sweat is precisely what eventually stinks. Every time a synthetic shirt goes in the wash, you are essentially trying to rinse grease out with water. Cotton, being hydrophilic, absorbs moisture rather than trapping it, and unlike polyester, it does not offer odour-causing bacteria a surface to colonise. Callewaert puts it plainly: “One, the surface absorbs odorous molecules very well, and it doesn’t wash off very well in the laundry machine. Two, the surface is an ideal breeding ground for smelly bacteria.”
Beyond the smell, cotton has a physical quality that synthetics cannot replicate over time. It is one of the rare fabrics that actually improves with age, softening a little more with every wash rather than pilling, roughening, or developing that ghostly sheen that makes old synthetic kit look like it belongs in a lost property bin.
The Return of the Running Tee
The aesthetic case is equally persuasive. Vintage running photographs tell the story well: Bill Rodgers winning his first of four Boston Marathons in 1975 was wearing cotton. Fred Lebow, the New York City Marathon founder, ran in a ringer tee. They looked like people who actually ran, rather than sponsored mannequins.
Some brands are responding to this shift. Tracksmith‘s Grayboy Tee is made in the USA from Varsity Cotton, with solid colour versions constructed from 100% Open End Cotton Jersey. The Heather Gray version uses a 90% Open End Cotton, 10% Black Poly Jersey blend. It is a deliberate callback to the look and feel of America’s 1970s running boom, and it sits alongside a broader resurgence in natural-fibre kit driven partly by growing concern about microplastics. Natural-fabric underwear companies are appearing in numbers, and their messaging is focused squarely on getting synthetic particles away from skin.
Merino wool offers another natural option for warmer or more variable conditions, handling moisture and temperature regulation without the petrochemical backstory. But for most people, the easiest entry point is already sitting in a drawer: an old band shirt, a faded charity race tee, something broken in over years of washing until it is exactly as soft as it needs to be.
Cotton does not ask you to spend money. It does not require a performance review. It just needs you to stop throwing it in the charity bag every time a new technical fabric promises to shave thirty seconds off your parkrun. Pull it out, lace up, and go. The Ghent University study gives you all the justification you need.
