Outdoor Exercise Doesn’t Raise Melanoma Risks

Considered the most dangerous form of skin cancer, melanoma can form even on skin not exposed to the sun, but according to the Skin Cancer Foundation, ultraviolet (UV) rays from sunshine are one of the top factors for melanoma development.

That’s because UV light can damage skin cells and lead to mutations that may cause skin cancer. Other factors also play a role, such as:

• Genetics/family history
• Fair skin
• Blue or hazel eyes
• Hair color, especially blonde or red hair
• Freckles
• Number of moles on the body
• Weakened immune system

Although it may seem that higher exposure from exercising outdoors regularly could boost risk, a recent study in Preventive Medicine suggests that’s not necessary true, as long as prevention strategies are put in place.

Study Results

Because previous studies on skin cancer, sun exposure, and athletes showed mixed results, Norwegian researchers looked at over 151,000 women aged 30 to 75 participating in a large-scale study on cancer done over nearly 20 years.

“There has been a positive association before between physical activity and risk of melanoma, and extended time outside seems like a plausible explanation for that,” says co-author Flavie Perrier, PhD, research fellow in the Institute of Basic Medical Sciences at the University of Oslo. “However, we found that walking outdoors, even done for two hours per day in the summer, actually decreased melanoma risk.”

There may be a few reasons for this, she adds. First is that physical activity, in general, has been shown to help reduce all types of cancer and has a protective effect on the immune system. For example, a study published in eLife found that physical activity changes the metabolism of the immune system’s T-cells, giving them greater capability in attacking cancer cells.

It's not clear from previous research how well that applies to melanoma specifically. While some studies have found that regular exercise may help to protect against melanoma, other studies have had different results.

However, says Perrier, regularly spending time outdoors allows your skin to adjust to sunshine gradually and reduces your risk of getting a sunburn. There is a strong association between sunburn and melanoma, so avoiding a burn through strategic exposure could provide more protection. Previous research suggests it doesn’t take many sunburn incidents to raise risk. One study, published in Cancer Epidemiology, Biomarkers & Prevention, found women who had at least five “blistering” sunburns before age 20 had an 80% increased risk for skin cancer.

 “Those who are more active are likely taking more precautions compared to those who are less active,” she states. That means even though they may be in the sun more frequently, they may be at lower risk for melanoma.

Playing It Safe

To protect yourself, the general recommendation is to use a sunscreen with at least a factor of 15 SPF, but the Skin Cancer Foundation suggests 30 SPF for extended periods outdoors.

For exercise, making a plan beforehand can be key, suggests Chris Gagliardi, MS, CSCS, scientific education content manager at the American Council on Exercise. That includes strategies such as:

• Apply sunscreen 30 minutes before going outdoors
• Reapply every hour, or more often if sweating or swimming
• Wear sun-protective clothing
• Avoid sun exposure between 10 a.m. and 3 p.m.
• Exercise in the shade when possible, and choose shady running routes

“Being outdoors in general when exercising has positive effects, not just on your physical health but also on your mental well-being,” says Gagliardi. “Making sure you take a few additional steps to protect yourself can go a long way toward reaping those benefits.”