By Danielle Pavliv
2015

Exercise reduces your risk of cancer and many other diseases, but running outdoors can increase your risk of skin cancer if you don’t follow a few simple rules.

Running is one of the most popular forms of exercise. It can be done anywhere, doesn’t require a gym or any special equipment (although some people prefer to use a treadmill)-just a good pair of shoes and comfortable clothing. Running outside — whether on a track, in the woods, or on a path by the river — can be a wonderful and restorative way to exercise. Nature and exercise are both great ways to improve your mood.

Running regularly can lower the risk of many health problems including heart disease, stroke, osteoporosis and bone fracture, diabetes, and obesity.[end Warburton DE, Nicol CW, Bredin SS. Health benefits of physical activity: The evidence. Canadian Medical Journal. 2006; 174(6):801-809.] In addition, it can improve mental health and blood pressure.[end Paluska SA, Schwenk TL. Physical activity and mental health: Current concepts. Sports Medicine. 2000;29(3):167-180.] However, many people don’t take proper precautions when they decide to go running outside, and the results can be deadly.

Imagine this: it’s a nice day outside, so you decide to go for a jog, wearing running shorts and a t-shirt. You probably don’t spend too much time thinking about what to wear — you simply notice what the temperature is, put on something comfortable, and go. Sunscreen seems like a hassle, and you think you’ll probably sweat it off anyway. It’s not like you will be laying out at the pool or playing golf all day, so how much harm can a 30-minute run cause anyway?

While many of us try to protect our skin when spending time outside, data show that just over half of all American adults usually take at least one of these three precautions:  seeking shade, using sunscreen, or wearing sun-protective clothing.[end Sun-Protective Behavior Rates. Skin Cancer. Centers for Disease Control and Prevention. August 2011. Available at: http://www.cdc.gov/cancer/skin/statistics/behavior.htm.] People who don’t do any of these are at much higher risk for skin cancer.

Skin cancer

Skin cancer is the most common of all cancers. In the U.S., accounting for almost half of all cancers and affecting over 2 million people each year. One in 5 Americans will develop skin cancer during their lifetime.[end Robinson JK. Sun exposure, sun protection, and vitamin D. Journal of the American Medical Association. 2005;294(12):1541-1543.] There are three types of skin cancer: basal cell, squamous cell, and melanoma. Basal cell carcinomas are the most common type of skin cancer. They rarely spread to other areas of the body, and are very treatable. Squamous cell carcinomas, on the other hand, can spread to organs and other areas in the body and can be fatal if they are not caught early. The third type of skin cancer, melanomas, are the least common but most dangerous — they kill more than 8,600 Americans every year.[end Skin Cancer Statistics. Centers for Disease Control and Prevention. April 2012. Available at: http://www.cdc.gov/cancer/skin/statistics/.] If found early, however, melanomas can be treated. Melanomas are most often caused by ultraviolet radiation from the sun or tanning beds. They usually resemble moles and are often black or brown. Most change over time, including an increase in size.[end National Cancer Institute. Signs and symptoms of melanoma. U.S. National Institutes of Health. January 11, 2011. Available at: http://www.cancer.gov/cancertopics/wyntk/skin/page8.] In recent years, incidence of melanoma has increased significantly, especially in those with fair skin. While melanoma is more prevalent in men than women, rates of diagnoses and death are increasing for both men and women.

Is exercising outside more risky than just relaxing outside?

In 2006, Dr. Christina Ambros-Rudolph and colleagues at the Medical University of Graz in Austria conducted a study to see if marathon runners are at higher risk of melanoma than people who don’t run as regularly.[end Ambros-Rudolph CM, Hofmann-Wellenhof R, Richtig E, Müller-Fürstner M, Soyer HP, Kerl H, Dermatol A. Malignant Melanoma in Marathon Runners. Archives of Dermatology. 2006;142(11):1471-1474.] They examined over 200 runners and found that they are at increased risk for skin cancer. In fact, runners who trained the most intensively had the highest rates of skin lesions. Almost all of the athletes wore shirts and shorts that did not totally cover their arms, back and legs, and only 56% wore sunscreen. Although there was a clear link between sun exposure and skin lesions, the researchers found another reason the athletes who had more intense workouts were more prone to skin cancer. Endurance exercise such as long-distance running suppresses immune function in the body, which is why extreme athletes are often more susceptible to infections than others. This can release a type of protein called cytokines, limiting the ability of the body’s immune system to fight off potential cancers. In addition, sweating a lot while outside is linked to skin cancer. The wetter your skin, the more UV rays are absorbed, which means that exercising on sunny days can be much more dangerous for your skin than just sitting or laying down in the sun.

How to stay safe outside

You don’t have to give up running outside — there are plenty of ways to protect yourself outside for exercise or any other activity. Try to do as many of these as possible each time you go out in order to lower your risk for melanoma or other types of skin cancer:

• Use a generous amount of sunscreen with a sun protection factor (SPF) of 30 or higher, even on cloudy days — cloud cover only blocks out one type of UV rays. Reapply often, especially if you are sweating or in the water. Use a water-resistant sunscreen that will stay on when you swim or sweat.
• Avoid the sun between 10 a.m. and 4 p.m., when UV rays are the strongest. If you want to go for a run outside, try to do it early in the morning or right before sunset.
• Put on some sunglasses with high UV absorption to protect your eyes, and a hat to protect your face.
• Wear clothes made of tightly woven fabrics that you cannot see through. Try to avoid regularly exposing areas of your body such as your shoulders, neck and chest. To prevent overheating, wear light-colored clothing that reflects the sun’s rays.
• Look for shade: try to do your stretches and other exercises in a shaded area.

Choosing a sunscreen

The American Academy of Dermatology recommends that everyone wears a water-resistant sunscreen of at least 30 SPF daily.[end American Academy of Dermatology Sunscreen Website. Stats and Facts. Prevention and Care. Sunscreens. 2012. Available at: http://www.aad.org/media-resources/stats-and-facts/prevention-and-care/sunscreens.] Further, they recommend using a broad-spectrum sunscreen that protects against both types of UV rays (UVA and UVB). You can use the Environmental Working Group’s website to find out which sunscreen really work and don’t contain a lot of harmful and even cancer-causing ingredients. The Food and Drug Administration (FDA) didn’t regulate sunscreen until June 2012. Prior to that date, there was no guarantee that the sunscreen you were slathering on your body actually protected you or did what the label claimed. Now, manufacturers are required to label their products accurately and are held to safety and effectiveness standards.[end FDA sheds light on sunscreens. U.S. Food and Drug Administration. June 2012. Available at: http://www.fda.gov/forconsumers/consumerupdates/ucm258416.htm.] When choosing a product, remember that a sunscreen with twice the SPF does not mean you can stay outside in the sun twice as long before you get a sunburn. The intensity of UV radiation matters just as much as how long you are in the sun, which is why it’s so important that you limit your exposure from 10 a.m. to 4 p.m.[end Jou PC, Feldman RJ, Tomecki KJ. UV protection and sunscreens: What to tell patients. Cleveland Clinic Journal of Medicine. June 2012;79(6):427-436.]

Make sure to regularly check your body for any new moles or scaly patches. If they change size, form or color, visit a dermatologist. If you have skin cancer in your family, you will likely want to get your moles checked regularly.

Sun damage is permanent and irreversible, so it’s important to take good care of your skin throughout your life. Remember — a tan is a sign of skin damage. There’s no such thing as a “healthy” tan!

For more information about the most dangerous type of skin cancer, see http://dev.stopcancerfund.org/t-skin-cancer/treating-skin-cancer-melanoma/