[A twin study in Qingdao and Lishui: heritability of exercise participation and sedentary behavior]

To investigate both genetic and environmental influences on the exercise participation and sedentary behavior in Qingdao, Shandong province and 326 in Lishui, Zhejiang province.

568 twin pairs, including 242 in Qingdao and 326 in Lishui, were studied. Exercise participation was measured by two questions on the frequency and intensity and then divided into two groups. Sedentary behavior was measured by one question as 'how long do you spend on sitting every day'. Variance component models based on twins was used to estimate the genetic and environmental factors on these traits.

The average age in monozygotic twins was (41.14 ± 10.11)while in dizygotic twins it was (41.23 ± 9.89). Genetic factors accounted 78% (35%-96%) and 59% (0-94%) for exercise participation variance in Qingdao and Lishui in people aged between 20 and 40. However, there were no heritability noticed on physical activity in people older than 40 years of age. Rates of heritability on sedentary behavior in Qingdao and Lishui were 68% (59%-75%) and 32% (7%-62%), respectively.

Results from the study suggested that sedentary behavior in Chinese people was influenced by genetic factors, which could also explain much of the exercise participation variance in people aged between 20 and 40.