UPF: Running Apparel with Sun Protection

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I am all about sunscreen. I’m the girl that reapplies after an hour on the beach. I’m the friend that will literally yell at you if you neglect to wear sunscreen in favor of getting a tan. With both of my parents having (and surviving) skin cancer, I grew up keenly aware to some of the risks associated with getting too much unprotected sun exposure. Not only does prolonged exposure to the sun lead to a higher risk of developing skin cancer, but it also ages the skin at a higher rate.

When it comes to UV protection, I’m not one to throw caution to the wind. I’ve always thought that clothing was a completely protective barrier from the sun’s harmful rays, so it came as a shock to me when I found out that this wasn’t the case. Yes, clothing is protective, but not 100% of the UV rays are blocked by your average t-shirt.

As runners, many of us spend a good amount of time in the sun. So we should be aware of how much (or how little) our clothing is protecting us. Beyond sunscreen for our skin and sunglasses to protect our peepers, we can wear clothing with a high UPF rating to protect our skin from exposure that we may not expect.

UPF stands for Ultraviolet Protection Factor, and it is the measure of how effectively a piece of clothing shields against the sun. The number represents what fraction of UV rays are making it through. For example, UPF 50 means that only 1/50th of the sun’s UV radiation is reaching your skin. So what determines the UPF rating in running apparel?


If you think that the color of a garment is a purely superficial characteristic, think again. Many dyes absorb UV rays, preventing them from penetrating the fabric and exposing your skin. Darker, richer, and brighter colors absorb more UV rays than lighter, pastel, or white pieces. So that super vivid pink tank is going to provide you with a higher UPF than that soft, rose colored racerback.


Fabric type

Fabrics are composed of different types of fibers. Most fiber types absorb some UV radiation, but synthetic fibers such as polyester, lycra, nylon, and acrylic are more protective than other fibers. Great news for those of us looking for protective running pieces! Most running apparel pieces are composed of these synthetic fibers. Take a look at the product tag or read the fabric composition details online while purchasing to see what exactly is woven into your gear.

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The tighter the knit or weave of a given fabric, the less UV rays get through. It kind of makes sense if you think about it. A looser weave has larger gaps within the fabrication… larger gaps in which UV rays can get through. If you were to look at a piece of fabric under a microscope, you can see the spaces between the fibers. When picking out running apparel, you have to also consider the breathability of the fabric for your comfort on the run. Ideally, twill and denim provide excellent UV protection with a super tight weave, but how many runners do you see wearing jeans? Yeah, that’s what I thought. We need a middle ground that provides some breathability and yet a tight enough weave to block out most of the UV rays.


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