A runner’s relationship with the sun is complicated. You love soaking up its warmth and energy, but you hate when it leaves its mark – age spots, tan lines, painful burns – and you dread the long-term damage that may result. There are, of course, reasons to be wary, especially if you’re logging lots of summer miles. But you might be surprised to learn that running in the sun also does your body good. Here’s how to balance the risks and rewards.
Sun is bad news for skin…
The sun’s ultraviolet rays can cause skin cancer, and runners may be especially vulnerable. A study in Archives of Dermatology found that marathoners showed increased numbers of abnormal moles and age spots, putting them at higher risk for malignant melanoma. Training outdoors increases runners’ exposure, but researchers cited another – less obvious – contributing factor: long-term intense exercise (such as marathon training) can suppress the immune system, increasing vulnerability to skin damage.
Adding insult to injury, when your immunity is suppressed you are also more susceptible to other, non-threatening (but still annoying), skin issues such as blisters and chafing. ‘Overexposure to UV radiation can suppress your skin’s ability to properly protect itself and heal,’ says Elizabeth Hale, a professor of dermatology at the New York University School of Medicine and a marathoner.
What’s more, UV rays can contribute to eye damage, such as cataracts and, according to research published in Clinical, Cosmetic and Investigational Dermatology, they are responsible for 80 per cent of the visible signs of skin ageing, including wrinkles.
READ: 3 ways to save your skin
… But you still need it
Knowing all that you may think you should never venture out on a sunny day. However, from a biological standpoint, sunshine is vital to your mental and physical health. ‘Being in the sun is part of a healthy physiology,’ says Martin Feelisch, a professor of experimental medicine and integrative biology at the University of Southampton.
Case in point: vitamin D, which your body makes when your skin is exposed to UVB rays. Around one fifth of UK adults may be deficient in the ‘sunshine’ vitamin. A lack of vitamin D is associated with depression, bone fractures, hypertension, autoimmune diseases and cancer – and too little sun exposure is the biggest reason why levels are low.
But that’s not the only role the sun plays in our health. Recent research from Edinburgh University reports that the skin contains large amounts of nitric oxide, a compound that dilates blood vessels to reduce blood pressure and lower the risk of heart attack and stroke. Sunlight activates those nitric oxide supplies and releases them into circulation, says Richard Weller, a senior lecturer in dermatology who conducted the research.
And here’s the kicker: time in the sun may also lead to faster race times, according to research presented at the American College of Sports Medicine conference in May 2014. After cyclists spent 20 minutes under a UVA lamp, they completed a 10-mile time trial faster than when they did it without the rays, says Chris Easton, an exercise physiologist at the University of the West of Scotland. ‘The large stores of nitric oxide released from the skin help more blood and oxygen flow to your muscles,’ says Easton. ‘Plus, by reducing the amount of oxygen the muscles use to produce force, the nitric oxide helps you go harder, longer.’ (The cyclists’ times were even faster than when they ate rhubarb and Swiss chard, which also increase circulating levels of nitric oxide, but to a lesser degree than the sun.)
Play it safe
‘Get out, but don’t get burned,’ says Feelisch. Even if you run when the sun appears closer to the horizon (before 10am and after 4pm) and wear sunscreen, you will get a fair amount of beneficial sun exposure, says Dr Ashish Bhatia, assistant professor of clinical dermatology at the Northwestern University Feinberg School of Medicine in Chicago, US. While sunscreen lowers your body’s production of vitamin D, your body will still produce a decent supply of the vitamin, according to a study conducted at St John’s Institute of Dermatology, King’s College London. And while studies haven’t yet examined the effect of sunscreen on nitric oxide levels, Feelisch says you’ll probably enjoy some of the benefit even if you apply it.
Increasing your immunological defenses can also help safeguard your skin from damage. Schedule rest and recovery time each week, get at least eight hours’ sleep each night and fuel up on antioxidants. ‘Focus on eating a balanced diet that is very colourful,’ Dr. Hale says. ‘The more colours, the wider the array of damage-fighting antioxidants you’re getting.’
No matter how careful you are, check your body for new or changing moles every month, and visit a dermatologist once a year or more (depending on your personal risk level) for a skin-cancer screening.