Sun protection for outdoor sports: a guide to SPF, UPF clothing and using them properly

In summer you might head out for a run, go for a ride or plan yourself a trekking route of a few hours. It sounds great, and it really is. But there’s a mistake most of us make right at the start: skipping sun protection.

Some of us forget, and some of us don’t bother because “it’ll be fine”. So it’s hardly surprising when we end up walking around with a red nose, burnt shoulders or the back of the neck stinging to the touch for days. Then there’s another group who put on sunscreen and think that’s the end of it.

When it comes to exercising outdoors, though, sun protection works a little differently. We’re outside for hours, we sweat, we wipe our faces or we get in the water. On top of that, when running, cycling, trekking and doing water sports, parts of the body can be exposed to direct sun for a long time.

That’s why, in outdoor sport, it isn’t just a matter of slapping on a high-SPF sunscreen. A better approach is this: the right time of day + as much physical protection as possible + suitable clothing + sunscreen.

So what’s the real difference between SPF 30 and SPF 50? Do you need a UPF 50 T-shirt? When should you reapply sunscreen? Let’s take a look together.

What’s the difference between SPF and UPF?

Once you start looking into sun protection, two terms keep cropping up: SPF and UPF. SPF is the protection rating used for products applied directly to the skin, like sunscreen. UPF describes the protection that textiles such as T-shirts, arm sleeves or hats give against ultraviolet rays.

In short:

• SPF = protection you put on your skin
• UPF = protection you wear

Don’t think of them as alternatives — they actually complement each other. Say you’re wearing a long-sleeved UPF 50 top. Your arms are covered by the fabric, but your face, the back of your neck, your ears and your hands may still be exposed. That’s exactly where sunscreen comes in.

The World Health Organization (WHO) also recommends thinking about shade, clothing, hats and sunglasses alongside sunscreen when it comes to sun protection; in other words, don’t put the whole burden on sunscreen alone.

What SPF should you use for outdoor sport?

For sunscreen used outdoors, the general recommendation is a broad-spectrum, water-resistant product with SPF 30 or higher. The American Academy of Dermatology also recommends all three of these together for exposed skin. If you do sport outdoors, it makes sense to treat SPF 30 as your minimum.

In the summer months, on days when you’ll be outside for a long time, or for activities where you’ll sweat a lot, you can look at SPF 50 or 50+ products. There’s one detail here that confuses people, though.

SPF 50 doesn’t give twice the protection of SPF 30

When you see the number 50, it’s easy to think “that’s almost twice as strong as 30”, but that’s not how it works. Applied in the right amount, SPF 30 filters out roughly 97% of UVB rays, and SPF 50 roughly 98%. So although protection goes up as the number rises, SPF 50 isn’t double SPF 30.

What I’d really pay attention to here isn’t just the SPF number on the product. Because in real life we sometimes don’t put on enough sunscreen, we sweat, we wipe our faces and we stay outside for hours. That’s why SPF 50 gives me a little extra safety margin.

For my part, I usually see SPF 30 as a good enough starting point. If the price difference isn’t ridiculous, I’d happily go up to SPF 50 as well. But the thinking should never be “I’ve put on SPF 50, so I’m safe all day”.

How much sunscreen do you need?

One of the most common mistakes is buying a high-SPF product and not using enough of it. In outdoor sport, your whole body usually isn’t exposed, so we can keep things a bit simpler. What matters is not missing the parts that are exposed:

• face
• ears
• back of the neck
• neck
• shoulders
• arms
• hands
• any exposed parts of your legs

Ears and the back of the neck in particular are very easy to forget. It’s also recommended to apply sunscreen to dry skin about 15 minutes before you go out. So rather than smearing something on your face in two seconds as you tie your running shoes and head out the door, it’s better to build it into your preparation a little earlier.

When should you reapply sunscreen?

The general advice is to reapply sunscreen roughly every two hours while you’re outside. In outdoor sport, though, it’s not right to treat this as a fixed alarm. If you’ve been sweating heavily, wiped your face with a towel or been in the water, you may need to reapply sooner.

The American Academy of Dermatology also recommends reapplying after swimming or sweating, as well as roughly every two hours. Once you think about it activity by activity, it all becomes a bit clearer.

A 45-minute run

If you’ve applied it properly before leaving home, stopping halfway through your run to put on more sunscreen won’t be practical for most people.

A 3-hour bike ride

It makes sense to take a small sunscreen with you. You can top up your face, the back of your neck, your ears and your arms in particular when you need to.

A 5-6 hour trek

Here I wouldn’t rely on a single application. I’d put the sunscreen not at the bottom of my backpack, but in a pocket I can reach easily.

SUP, kayaking or windsurfing

With water in the mix, reapplying becomes even more important. You should also check the water-resistance time on the product.

What does “water resistant” mean?

In sports where you sweat a lot, and in water sports especially, one of the phrases worth looking for on the packaging is “water resistant”. But there’s an important distinction here: water resistant means it holds up in water, whereas waterproof means water can’t get through at all. And there’s no such thing as a “waterproof” guarantee for sunscreen.

Under FDA rules, water-resistant sunscreens have to be labelled according to whether they keep their protection for 40 or 80 minutes in standard tests. So a product that says “Water Resistant – 80 minutes” shouldn’t be read as “I put it on in the morning, so I can go in and out of the sea all day”. On long SUP, kayaking, windsurfing or swimming sessions, reapplying still matters.

Do you really need UPF clothing?

Not for every outdoor activity. I don’t think you need to build a special UPF wardrobe for a 45-minute morning run. But for activities where you’ll be out in the sun for hours, UPF clothing can be really handy.

UPF shows how much protection a fabric gives against UV rays. A UPF 50 fabric, for example, blocks roughly 98% of UV rays. In particular:

• on long trekking routes
• on long bike rides
• when SUPing or kayaking
• when windsurfing
• in training sessions lasting hours out in the open

UPF clothing makes sense to me. Its biggest advantage is convenience: instead of putting sunscreen on a covered area again and again, you protect that area directly with fabric. In terms of outdoor clothing, it’s a solution that needs much less upkeep than sunscreen.

Does a normal sports T-shirt protect you from the sun?

Most of us were put in an ordinary T-shirt at the beach as kids to keep the sun off. But does it actually work? Yes. The fact that a T-shirt doesn’t have a UPF label doesn’t mean it gives no UV protection at all.

How much protection you get can vary with the fabric, though. Tightly woven fabrics generally block more UV, and dark colours can increase protection in some fabrics too. In outdoor sport, another factor comes into play: heat and breathability.

Running in a thick, heavy T-shirt in midsummer because “tightly woven fabric protects better” doesn’t make much sense either. How light and breathable our clothes are has a direct effect on both our comfort and how much we enjoy the sport.

So if I’m buying a technical outdoor top, the combination I’d look for is: light + breathable + quick-drying + high UPF protection. In other words, just looking at the UPF number on the label isn’t enough.

Won’t long sleeves make you hotter?

You’ve probably seen people exercising in long sleeves in summer. I used to catch myself thinking, “It’s already hot, and they’re wearing long sleeves on top of that.” But once the lightness, thinness and breathability of the fabric come into play, things look a bit different.

Light, long-sleeved UPF tops can be really handy for trekking and water sports in particular. For running, I think it’s more a matter of personal preference. On short, fast runs I personally go for short sleeves. But for an outdoor activity lasting hours, a thin, breathable long-sleeved top makes a lot more sense.

Don’t forget a hat and sunglasses

In your sun protection system, don’t put the whole burden on sunscreen. In outdoor sport, a hat, sunglasses, neck protection and suitable clothing are all part of the system too.

A wide-brimmed hat might not be practical for running, where a lightweight running cap works better. For trekking, you could go for styles that cover more of your neck and ears. And on the bike, even though a helmet covers most of your head, your face, ears and especially the back of your neck can still be exposed.

With sunglasses, too, don’t just go by how dark the lenses look; check for genuine UV protection. The WHO recommends sunglasses that block 99-100% of UVA and UVB. I went into what each type of lens does in detail in my running sunglasses guide.

Do you need sunscreen when it’s cloudy?

It’s easy to think, “There’s not even any sun today, it’ll be fine.” But feeling less of the sun’s heat when it’s cool or cloudy doesn’t mean the UV radiation has gone away. So when you’re doing sport outdoors, it’s better to look not just at the temperature but at the UV index as well.

Put simply:

• UV 0-2: low
• UV 3-5: moderate
• UV 6-7: high
• UV 8-10: very high
• UV 11+: extreme

The WHO recommends taking sun protection measures once the UV index reaches 3 or above. On days when I’ll be training outside for a long time, checking the UV index alongside the temperature when I look at the forecast is, I think, one of the easiest habits you can pick up.

Sun protection by sport

Running

One of the main issues with running is sweat. A basic combination could be: SPF 30-50+ water-resistant sunscreen + a light cap + sunglasses with UV protection. On short runs, applying it properly at the start makes life much easier; the longer you’re out, the more you need to factor in reapplying.

Trekking

Because treks last longer, I wouldn’t rely on sunscreen alone. My choice would be a UPF top + hat + sunglasses + sunscreen on any exposed skin. Don’t forget the back of your neck and your ears in particular.

Cycling

On the bike, the wind can make you feel the sun’s effect less than it really is. But on long rides especially, you can be in the sun for hours. The back of the neck, ears, arms, hands and exposed parts of the legs are easily forgotten. On long rides, UPF arm sleeves can be a practical alternative too.

SUP, kayaking and windsurfing

In water sports you need to take protection a bit more seriously. Here, one of my first choices would be a long-sleeved UPF 50+ top + water-resistant SPF 50+ sunscreen. That way you cut down the amount of exposed skin and don’t leave all the protection to sunscreen alone.

The most common sun protection mistakes in outdoor sport

Most of the common mistakes actually come not from buying the wrong product but from using it the wrong way. These six are the ones I come across most often out there:

1. Thinking one application in the morning will last all day. On long activities you need to reapply.
2. Only putting it on your face. Ears, the back of the neck, hands and exposed parts of the legs are very easy to forget.
3. Only looking at the SPF number. Broad-spectrum protection matters too, and so does water resistance, especially when sweat or water is involved.
4. Thinking “water resistant” and “waterproof” are the same thing. No sunscreen stays water-resistant forever.
5. Assuming UV is low because it’s cool. Temperature and UV level aren’t the same thing.
6. Relying on sunscreen alone. Clothing, a hat, sunglasses, shade and, where possible, the time of day you exercise are all part of your sun protection system.

The WHO also recommends cutting down on exposure to strong sun where possible, especially in the middle of the day. In summer, moving your run to the morning or evening does exactly that.

The bottom line

With SPF, UPF, UVA and UVB all flying around, the subject can look a bit complicated at first. But there’s really no need to make sun protection in outdoor sport this hard. The simplest system is this: check the UV index, choose times when the sun is weaker if you can, add more physical protection with clothing on long activities, and put suitable sunscreen on any exposed skin.

On a short run, sunscreen, a cap and sunglasses can make a good foundation. On a trek or bike ride lasting hours, UPF clothing makes a lot more sense. And for water sports, a long-sleeved UPF top with water-resistant sunscreen is a very practical combination.

In short, it’s not about buying the highest SPF number on the shelf, but about using the right product, in the right amount, at the right time.