Can You Run in Swim Shorts or Trunks? (4 Crucial Caveats)

Whether you’re a beachgoer with a sudden need for speed or just curious about the versatility of your swimwear, you might wonder if you can run in your swim trunks. However, you might be better off asking yourself if you should.

While you can run in swim shorts or trunks, it is unlikely that you have an ideal running experience in them. Unlike swimwear, running shorts are designed with the needs of runners in mind, including a moisture-wicking outer material, a running liner, v-notches to improve the runner’s range of motion, and zipper pockets for securing an id or key.

Keep reading to learn more about the differences between swim trunks and running shorts.

Is it okay to run in swim shorts?

Deciding what gear to run in is a personal decision, but you want to be as informed as possible when selecting something as crucial as running shorts. Is it possible to use swim shorts in place of running shorts?

It is possible to run in swim trunks, but it’s not recommended. Most swim trunks tend to be both longer and tighter than swim shorts, meaning they will be more restrictive during a run. While both styles of shorts may have a special liner beneath the outer layer, they serve very different purposes. The running liner is necessary for support and moisture control, whereas the quick-dry mesh liner of swim trunks may lead to discomfort and chafing.

For a short run, or with specific modifications, it may be possible to run comfortably in swim trunks, but they are not a good choice for serious runners.

What is the difference between running shorts and swim trunks?

While there are many variations of both running shorts and swim trunks, there is typically very little overlap between the details of their designs. There are differences between the two garments, some more obvious than others. 

Security, comfort, performance, and style are areas that may be negatively affected by the decision to forgo running shorts in favor of swim trunks. The primary difference between swim trunks and running shorts are in their:

  • Liners
  • Design
  • Materials
  • Performance

There are various things to consider, ranging from comfort to sweat management. Let’s take a closer look to tease out some of the main differences. 

Liners

Both swim trunks and running shorts may come with a built-in liner; however, these liners serve very different functions. 

In running shorts, liners will be made of synthetic material, providing security and moisture protection to the groin area. Swim trunks are made of meshy material and won’t help with these issues. 

Swim trunk liners decrease dry time and prevent clinging when the shorts are wet. When used as running shorts, this meshy liner could create friction problems that may lead to chafing. 

It would be best to avoid mesh-lined swim trunks as running shorts unless you already have a base layer that prevents rubbing.

Design

The most apparent difference between running shorts and swim trunks will be in their overall design. 

There are three main types of running shorts: 

  • V-notch
  • Compression
  • Split-leg

V-notch shorts have a v-shape cut into the sides to increase the range of motion for the runner. Compression shorts compress the legs of the runner, decreasing wind resistance and friction. Finally, split-leg shorts have a slit cut up the sides to the waistband. Swim trunks will have none of these runner-friendly features.

Another feature to consider is zipper pockets, which can help keep wallet and keys secure. You will be hard-pressed to find a pair of swim trunks that accounts for any of these distinct features, mainly because these are items that you very much do not want joining you in the pool or ocean.

Materials

While both swim trunks and running shorts are often made of lightweight fabrics with water-resistant features, running shorts are designed with sweat resistance in mind instead of complete submersion. 

Many styles of running shorts use moisture-wicking fabric. Moisture-wicking technology keeps the individual beads of sweat on the outside of the fabric where they can be evaporated by sunlight. 

This concept is different than the water-resistant materials used for most swim trunks. Instead of transporting sweat from the skin through the outside of the fabric, water-resistant swim trunks may trap the sweat directly on the skin, causing chafing.

Performance

Depending on the swim shorts you’re attempting to use, your performance is not likely to improve and may even decrease dramatically when used in place of proper running shorts.

The lighter and less restrictive the swim trunks, the more likely you will maintain your performance level. Heavier, more restrictive shorts can inhibit performance. There’s a reason why you don’t see marathoners in board shorts! 

The use of moisture-wicking fabrics doesn’t seem to have much of an impact on performance. According to a study in the International Journal of Athletic Therapy and Training, there is no noticeable difference in the overall body temperatures of runners using moisture-wicking materials versus runners using traditional materials like cotton.

Can I convert my swim trunks to running shorts?

If you do have swim shorts that you want to convert to running shorts, it may be worth a try. Don’t attempt this on your favorite pair of swim trunks, though!

To convert swim trunks into running shorts:

  1. Choose the lightest material swim trunks that you have. 
  2. Cut a slit on the outside of each leg all the way up to the waistband.
  3. Remove any mesh liner from the inside of the shorts.
  4. Convert the pockets by sewing on zippers.

Trunks made of 100% polyester will be more wrinkle-resistant and will dry more quickly, which might improve your experience.

Some swim shorts come without a mesh liner and with zipper pockets already included, which can save you some time. While these may not be ideal running shorts, they can be used in a pinch.