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Ask the Coach

I slathered on some sweat-proof, hypo-allergenic, SPF 45 sunblock and felt smothered. What gives?

Illustration by Jeremy Duncan

I slathered on some sweat-proof, hypo-allergenic, SPF 45 sunblock and felt smothered. What gives?

—Tom Paul Geha, Los Angeles, CA

We consulted a few experts, and found that avoiding sunscreen isn’t the answer (sunburns can elevate body temperature, which could put a kink in your summer training success). The solution is choosing the right sunscreen concoction.

Basically, sunscreen is made of organic or inorganic compounds combined with a carrier, such as oils and water, and hocus-pocused into a potion that, when applied, creates a film on your skin. The film blocks the sun’s searing rays, but it also covers up sweat glands and follicles. If the film is too dense or thick, you can’t sweat effectively (or cool yourself with the evaporation), creating that smothered sensation.

“You’re really feeling the reduced ability to sweat,” says Steven Johnson, president of the sunscreen producer Sol Sunguard. Johnson says to avoid heavy, thick sunscreens, such as ones made with a lot of petrolatum, heavy waxes (e.g. beeswax) or tropical oils (e.g. coconut oil). Also, avoid sprays that have acrylic adhesives, a.k.a. acrylates, since they are too glue-like for activity, albeit great for lying around on a beach.

Johnson advises a sweat- or waterproof sunscreen, so you stay protected longer. The trick is picking one that is lightweight enough that you don’t feel smothered. Sample a dab in the store for feel and smell, then trail test it. Apply sunscreen 30 minutes before a run so it “sets up” on the skin and improves sweat’s ability to permeate.

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