Adverse associations of car time with markers of cardio-metabolic risk

Takemi Sugiyama, Katrien Wijndaele, Mohammad Javad Koohsari, Stephanie K. Tanamas, David W. Dunstan, Neville Owen

To examine associations of time spent sitting in cars with markers of cardio-metabolic risk in Australian adults. Data were from 2800 participants (age range: 34-65) in the 2011-12 Australian Diabetes, Obesity and Lifestyle Study. Self-reported time spent in cars was categorized into four groups: ≤15 min/day; >15 to ≤30 min/day; >30 to ≤60 min/day; and >60 min/day. Markers of cardio-metabolic risk were BMI, waist circumference, systolic and diastolic blood pressure, triglycerides, HDL-cholesterol, fasting plasma glucose, 2-hr plasma glucose, a clustered cardio-metabolic risk score, and having the metabolic syndrome or not. Multilevel linear and logistic regression analyses examined associations of car time with each cardio-metabolic risk outcome, adjusting for socio-demographic and behavioral variables and medication use for blood pressure and cholesterol/triglycerides. Compared to spending 15 min/day or less in cars, spending more than 1 hr/day in cars was significantly associated with higher BMI, waist circumference, fasting plasma glucose, and clustered cardio-metabolic risk, after adjusting for socio-demographic attributes and potentially relevant behaviors including leisure-time physical activity and dietary intake. Gender interactions showed car time to be associated with higher BMI in men only. Prolonged time spent sitting in cars, in particular over 1 hr/day, was associated with higher total and central adiposity and a more-adverse cardio-metabolic risk profile. Further studies, ideally using objective measures of sitting time in cars and prospective designs, are needed to confirm the impact of car use on cardio-metabolic disease risk.