What to Wear Under a Triathlete Swimsuit

Small-chested women can get by with nothing under their swimsuits.
i Mike Powell/Lifesize/Getty Images

You’ve trained for months for your triathlon, but if you haven’t spent time trying out your clothing for race day, you might be in for a shock. Clothing for training is easy. When you swim, you wear a swimsuit; when you bike, you wear your bike shorts; and when you run, you wear a sports bra and running shorts. All this changes on race day. Unless you want to spend more time changing clothes than racing, you need to plan your transitions well before the race.

Think Ahead

    Most likely, you don’t want to finish your triathlon with a pair of black eyes. Unless you’re very small-chested, you’re going to need some kind of additional support for the run. If you have a tank top or tri top with built-in support that you like for running, you can try to slip that on after the swim. Just remember that you’ll be soaking wet. Anyone who’s ever tried to slip on a pair of skinny jeans on a humid day knows that skin-tight clothes and wet skin don’t make a good combination. A better option would be to wear your sports bra under your swimsuit. This works for one-piece and two-piece swimsuits.

Material Concerns

    Not just any sports bra will work for a triathlon, especially if you’ll be wearing it under your swimsuit. While cotton might feel great on your skin during your normal life, it will make your life miserable in a triathlon. During the swim, it will become completely water logged, and because it doesn’t dry fast, you’ll spend your bike and your run with a soaking wet bra. Instead, choose a sports bra that’s made from a moisture-wicking fabric.


    If you have sensitive skin, any bit of clothing you wear that has seams can cause some major chafing problems, even during sprint-length triathlons. Before your race, protect your skin under your swimsuit with an anti-chafing product. There are tons of options -- creams, gels, liquids and high-tech formulations. Each anti-chafing product has its advantages and disadvantages, so you’ll have to do some experimentation to find out what works for you. One thing’s a must, though: apply the product under your swimsuit, under every seam. Don’t forget the two major problem areas: under your armpits and on top of your collar bones.

Take a Test Drive

    The last thing you want to do is try out a new combination of clothes or a new anti-chafing product on the day of your triathlon. You don’t want to get halfway through your run and realize that the swimsuit top you thought was supportive is not quite gold-medal quality. Nor do you want to realize that the bottoms of your swimsuit cause some pretty intense chafing when you wear them on your bike. Try out your clothes numerous times over the course of your training.

Future Races

    While a swimsuit functions perfectly well in a triathlon, if you’re planning on competing in more races, consider investing in a tri suit. Tri suits come in a variety of forms, so you can find one that suits your needs and comfort level. One-piece tri suits offer tummy coverage, but they are very difficult to remove if you have to make a pre-race pit stop. The two piece tri suits make a visit to the restroom easy, but they leave your tummy exposed and the waistband can chafe a bit. Either way, these suits have bottoms the length of shorts, so you won’t have to struggle to get your wet body into your bike shorts. Just be aware that these shorts don’t have the same amount of padding as standard bike shorts. Take them for a spin several times before race day to see how they feel. Another option for future races would be a wetsuit. Slip it on over your regular biking/running attire for the swim. You don’t have to worry about a swimsuit at all.

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