In summer running, especially in hot, humid areas, clothes easily become soaked and stick to the body; at that point many runners simply take their tops off and run shirtless.
Some think that's the best way to cool down, while others find wearing a quick-dry singlet more comfortable. So, in terms of body heat loss and running performance, does running shirtless actually have an advantage?
Answer: yes, you can run shirtless, but the idea that "the less clothing, the cooler" isn't always true. How you feel ultimately depends on air temperature, humidity, solar radiation, wind speed, run intensity, and the clothing itself.
01
Sweat evaporation is the key to cooling
When you run, the large amount of energy produced by your muscles is ultimately released as heat. To prevent core temperature from rising continuously, the body increases skin blood flow and produces a lot of sweat.
At that point, cooling depends on the heat carried away when sweat evaporates. In other words, whether you feel cool comes down to whether that sweat actually evaporates.
If the air is dry and there's wind, sweat evaporates easily, and exposing skin by going shirtless can indeed feel more refreshing; but in high-humidity environments where the air is already near saturation, even if you remove your top the sweat won't evaporate and you won't feel any better.
That's why during the rainy season, in coastal cities, or on still, muggy nights, you can run shirtless and still feel like you're soaked. The problem isn't the clothing — it's that evaporative cooling itself isn't working.
02
Does wearing clothes impede heat loss?
Although sweat evaporation is closely tied to the environment, it also partly depends on what you wear while running. A heavy cotton T-shirt that clings to the skin when soaked can certainly increase that clammy feeling; but a thin, breathable, loose-fitting running top doesn't necessarily interfere significantly with thermoregulation.
Research shows that different fabrics and garment constructions affect thermal comfort, skin wetness sensation, and heat exchange — in other words, clothing isn't inherently the enemy of cooling.
A suitable running top can wick sweat away from the skin, increase the area available for evaporation, and prevent wet fabric from repeatedly rubbing the skin. Especially with wind, a lightweight top won't necessarily make you noticeably hotter.
So for most recreational runners, the difference between running shirtless and wearing a proper quick-dry singlet is more about subjective comfort.If you strip off your top hoping to "boost performance," you shouldn't expect too much.
03
Whether you go shirtless depends on the environment
If you're running at dawn, dusk, or in shaded conditions, running shirtless is mainly a comfort choice; but if you're out at midday on a summer day, it's about more than just feeling hot.
A shirt also acts as a layer of sun protection.The World Health Organization advises taking protective measures when the UV index reaches 3 or above, emphasizing shade, clothing, and sunscreen as important ways to reduce UV exposure. The U.S. CDC likewise notes that covering skin with clothing and using sunscreen can lower excessive UV exposure during outdoor exercise.
Going shirtless leaves large areas — shoulders, chest, back, and waist — directly exposed to sunlight.If you're out for a one- or two-hour run, cumulative UV exposure can be significant. Therefore, in strong sunlight it's still advisable to wear a lightweight, breathable, sun-protective top to avoid prolonged, large-area skin exposure to UV.
But running shirtless isn’t without advantages in certain situations. When clothing soaks up sweat it increases friction against the skin—especially on long runs, in rain, or in high-humidity conditions—making it easy to rub the skin red or even break it. For people prone to that problem, running shirtless can indeed be more comfortable.
04
When is it appropriate to run shirtless?
If the weather is hot but the sun isn’t strong, the route is safe, the venue allows it, and you personally feel more comfortable shirtless, you can absolutely run that way.
If you’re running for a long time under strong midday sun, or your skin burns easily, it’s better to wear a lightweight, breathable sun-protective top; and if you’ll be carrying a pack, vest, or hydration bladder, you should prioritize avoiding chafing.
When entering gyms, commercial facilities, school tracks, or taking part in organized races, you must follow the venue and event dress codes.Public spaces are not just training grounds but places where other people carry out their normal activities. Whether you can go shirtless is sometimes not a sports-science question but one of venue rules and social norms. While staying comfortable, be mindful of the specific setting.
So running shirtless can, in some cases, effectively reduce clothing stickiness and friction, making you feel more comfortable in breezy, low-humidity conditions.
The real issue for summer running is improving the body’s heat-dissipation efficiency,If you feel freer running without a shirt, then it’s a suitable choice; if you need sun protection or are constrained by public settings, a lightweight, quick-dry top will not hold back your training either.
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Text / Editor: Paoye / JOJO
Image credit: Paoye Big Bang
Visual: Max
