The best underwear for a marathon is a smooth, lightweight pair with flat seams, a waistband that stays put and a fabric that dries fast. Choose it weeks ahead, run your long sessions in it and keep race day free of surprises.
Why underwear matters over 42 kilometres
A short jog forgives a lot. A marathon does not. Over several hours, a seam that sits slightly wrong or a waistband that rolls becomes the thing you think about at kilometre 30. The goal is simple: you should forget you are wearing anything.
- Fabric: thin, stretchy and quick-drying beats thick and plush.
- Seams: flat and minimal, especially around the legs and pouch.
- Waistband: snug enough to hold, soft enough not to dig in.
- Cut: low-rise, short-leg shapes keep fabric out of the way of your stride.
Four cuts worth considering
| Cut | Best for | Keep in mind |
|---|---|---|
| Trunks / boxer briefs | Long distances, warm weather | Short leg suits most runners |
| Briefs | Minimal fabric, easy movement | Check the leg opening fit |
| Jockstrap | Open back, firm support in front | Try the waistband on a long run first |
| Longer compression shorts | Runners who like a layered feel | See our long ride guide for fabric tips |
Trunks: the steady all-rounder
A trunk with a short leg is the easiest choice for most runners. The Ice Silk Trunks are made from soft modal fabric that dries fast and wicks moisture, with a low-rise cut, soft flat seams and mesh panels for airflow. The Mesh Boxer Briefs go for all-over mesh and a roomy pouch with a short-leg cut. Browse more in our boxer briefs collection.
Briefs and jockstraps for minimal fabric
If you prefer less material, a sport brief is a clean option. The Cotton Sport Briefs are 93.2% cotton and 6.8% spandex with a 1.5-inch elastic waistband. Cotton is comfortable for training, but if you tend to run hot, try it on a long run before race day.
Jockstraps appeal to runners who want support in front and nothing at the back. The Classic Jockstrap has a wide elastic waistband and a breathable knit pouch, and the Mesh Jockstrap uses eyelet mesh and is made for running, the gym and cycling. The full range lives in our jockstrap collection.
Race-week checklist
- Never wear anything new on race day. Wear your chosen pair on at least two long runs.
- Check the waistband after 60 to 90 minutes: does it still sit flat?
- Pack a spare pair in your bag for after the finish line.
- Wash on a gentle cycle and air dry. Our washing guide covers the details.
- If you have a favourite colour, buy two so training and race day match.
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Frequently asked questions
Should I wear underwear under running shorts?
It depends on the shorts. If they have a built-in liner you can skip it. If not, choose a thin, seamless-feeling pair that dries quickly.
Is cotton or a synthetic better for a marathon?
Quick-drying fabrics such as modal blends and mesh usually feel lighter over long distances. Cotton works well for many runners, so test it on a long training run.
How many pairs should I take on race day?
Wear one, and pack one fresh pair for afterwards. A change at the finish feels better than any recovery snack.
Can I wear a jockstrap for running?
Yes, many runners do. Try the waistband and fit over a long distance before race day.
Ready for the start line?
Browse our sportswear collection and find a pair that disappears on the road. Every order ships in discreet packaging.
