Long car commutes risk health

Individuals with the longest commutes by car to and from work were the ones least likely to report frequently engaging in moderate to vigorous exercise, and most likely to show risk factors for poorer cardiovascular and metabolic health These were the findings of a new study by Dr Christine M. Hoehner of Washington University in St. Louis, Missouri, in the US, and colleagues, that is published in the June issue of American Journal of Preventive Medicine. Hoehner told the press: "This study yields new information about biological outcomes and commuting distance, an understudied contributor to sedentary behavior that is prevalent among employed adults." ""It provides important evidence about potential mediators in the relationship between time spent driving and cardiovascular mortality," she added. As working people move further away from urban centres, so the tendency is to spend more and more hours in the car commuting to and from work. We already know that spending too much time sitting is not good for cardiovascular and metabolic health. But we know little about the extent to which this applies to car commuting, write the authors. Hoehner and colleagues found that longer commuting distances were linked to reduced cardiorespiratory fitness (CRF), increased weight, and other indicators of metabolic risk. For their study, they used data on 4,297 people who lived and worked in eleven counties in the Dallas-Fort Worth or Austin, Texas metropolitan areas. All the participants had had comprehensive medical checks between 2000 and 2007, and their records also included geo-coded addresses of home and workplaces. For health indicators, the researchers included in their analysis CRF, body mass index (BMI), and a range of metabolic risk variables including: waist circumference, fasting triglycerides, fasting plasma glucose, high-density lipoprotein (HDL) cholesterol, and blood pressure. The participants had also filled in questionnaires about daily exercise, from which the researchers were able to assess their moderate to vigorous physical activity in the previous three months. For commuting distances, they applied mapping and geographic software to the geocoded addresses to calculate the shortest driving distances between home and work. The results showed that the participants who drove the longest distances to work reported engaging less frequently in moderate to vigorous physical activity. They were also the ones with the lowest CRF, and the highest BMI, waist size, and blood pressure. The link with blood pressure stayed the same when the researchers adjusted for physical activity and CRF, and was also still present for BMI and waist size, although to a lesser degree. In particular, commuting more than 10 miles to work was linked with high blood pressure. Also, those participants who commuted further than 15 miles to work were the least likely to be exercising at the level recommended by government guidelines, and the ones most likely to have BMIs in the obese range. Hoehner said, given the link between commuting distance and physical activity and CRF, that longer commutes could be displacing time spent in physical activity, since the effect on BMI was lessened somewhat when adjusting for physical activity. However, "... both BMI and waist circumference were associated with commuting distance even after adjustment of physical activity and CRF, suggesting that a longer commuting distance may lead to a reduction in overall energy expenditure," she added. She and her colleagues conclude: "This study contributed additional information about possible mechanisms underlying the increased risk of obesity, hypertension, and poor physical health observed among adults living in more-sprawling communities." "Multilevel strategies in the home, worksite, and community settings will be needed to mitigate the negative health consequences of long commutes faced by a substantial segment of the U.S. population," they urge. They also point out that car commuting is only one of many types of sedentary form, and the study did not take others into account, such as watching TV or sitting at work. Hoehner said we need more research to assess sedentary time across a range of behaviors to establish more securely the independent effects of commuting on health.