Bicycling and brisk walking associated with less weight gain in obese, premenopausal women

Bicycling and brisk walking are associated with less weight gain among pre-menopausal women, especially those who are overweight and obese, according to a report in the June 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Additionally, the report finds that slower walking does not appear to offer the same benefits as brisk walking.

According to background in the study, in the United States, 66 percent of adults are overweight or obese, 16 percent of children and adolescents are overweight and another 34 percent of children and adolescents are at risk of being overweight. Additionally, only about 0.5 percent of the commuting population in the U.S. age 16 and older ride bicycles, of which only 23 percent are female. "To our knowledge, research has not been conducted on bicycle riding and weight control in comparison with walking," the authors write. "Our objective was to assess the association between bicycle riding and weight control in premenopausal women."

Anne C. Lusk, Ph.D., of the Harvard School of Public Health, Boston, and colleagues, studied 18,414 women who participated in the Nurses' Health Study II, which is an ongoing study of more than 116,600 U.S. female nurses who were age 25 to 42 when the study began in 1989. The current evaluation included women who were premenopausal through 2005, focusing on weight change in participants between 1989 and 2005.

The 1989 baseline characteristics of the study found that 50 percent of the women spent time slow walking, 39 percent reported spending time walking briskly and 48 percent reported they spent time riding a bicycle. In 2005, participants on average reported spending more time walking briskly, some time walking slowly and the least amount of time bicycling. Additionally, the average time spent sitting at home was five times as much as time spent in total activity.

According to the results of the study, women who did not bicycle in 1989 but increased their bicycling by 2005 were less likely to have gained weight, even when riding for five minutes a day. Even less weight gain was seen with greater duration of bicycling. Comparatively, women who initially bicycled for more than 15 minutes day in 1989 but decreased time by 2005 gained more weight. Additionally, normal-weight women who bicycled more than four hours a week in 2005 had lower odds of gaining more than 5 percent of their baseline body weight, as reported in 1989, compared with those who reported no bicycling.

There is a significant relationship between increased time spent bicycling in 2005 and odds of weight gain, according to the study. "The results appeared to be stronger in women with excess baseline weight compared with lean women. The mean [average] weight gain was the smallest in women who engaged in four hours a week or more of bicycling compared with women who bicycled for less time." The authors also found that, "the benefits of brisk walking, bicycling and other activities were significantly stronger among overweight and obese women compared with lean women, whereas slow walking continued to show no benefit even among overweight and obese women."

"Unlike discretionary gym time, bicycling could replace time spent in a car for necessary travel of some distance to work, shops or school as activities of daily living," the authors conclude. "Bicycling could then be an unconscious form of exercise because the trip's destination, and not the exercise, could be the goal."
(Arch Intern Med. 2010;170[12]:1050-1056. Available pre-embargo to the media at www.jamamedia.org.)