Monday, August 8, 2016

Virtuous cycling: lower diabetes risk, but wear a helmet

- Kenny Lin, MD, MPH and Jennifer Middleton, MD, MPH

I (Jennifer) live in a community with a wonderful bicycle path system, and around this time of year it gets a lot of use. In a 2011 Letter to the Editor titled "The Virtuous Cycle," AFP Deputy Editor Mark Ebell, MD, MS encouraged readers to advocate in their communities for "safe, convenient, and enjoyable places to walk, run, and bike" rather than continuing to "harangue our patients about exercise and be frustrated when they do not listen to us."

Sensible advice, but do recreational and commuter cyclists have better health outcomes than non-cyclists, is it enough to cycle during only part of the year, and is it ever too late to get on the bike? A prospective cohort study of more than 50,000 Danish men and women recruited between the ages of 50 and 65 and followed for an average of 14 years recently provided answers to these questions. In a multivariable analysis, both seasonal and year-round cyclists had up to a 20 percent reduced relative risk for developing type 2 diabetes, even if they started cycling late in life.

The health benefits of cycling can be easily negated, though, by the risks of not wearing a helmet. Even though helmet-wearing cyclists are more likely to survive trauma than those not wearing helmets, and despite laws mandating helmets across the country, many bicycle riders continue to go bareheaded. A 1999 survey found the most common reasons for not wearing a helmet included "uncomfortable," "annoying," "it's hot," "don't need it," and "don't own one." This survey also found that peer and/or parent wearing of helmets increased the likelihood that children wore them too.

A review of children's cycling accidents from the National Trauma Data Bank found that white children and/or children with private insurance were much more likely to wear a helmet than African-American children and/or children with Medicaid. Another study in Los Angeles County found lower helmet use among older children, non-white children, and children from a low socioeconomic status. Programs that give away free helmets to children either in schools or in physicians’ offices increase helmet use and may reduce health disparities. Although physician counseling also increases helmet wear in patients under age 18, in one survey less than half of physicians providing care to this age group provided it. Unfortunately, there haven't been any studies of interventions to increase helmet wearing in adults.

The bottom line is that encouraging patients to start cycling for long-lasting health benefits should be accompanied by counseling on the importance of wearing helmets.