Age, period and cohort effects on adult physical activity levels from 1991 to 2011 in China

Abstract

BackgroundTo date no work has differentiated the effects of age, period, and cohort on physical activity (PA) among Chinese adults, while also considering biological, behavioral, economic, and environmental factors over time.MethodsWe used data from the China Health and Nutrition Survey (CHNS) between 1991 and 2011 (20 years). The outcomes of interest are metabolic equivalent of task (MET) hours per week from work and domestic activities. Age, individual characteristics, household size, asset ownership, urbanization were included as covariates. Analyses for adult (≥20y) males (n = 29,343) and females (n = 31,094) was conducted to explicitly assess differences in PA due to age vs period effects, and implicitly assess differences by cohorts due to the period-specific experiences across individuals of varying ages.ResultsThe mean age of the sample rose from 41.31 to 50.8 years and PA decreased from 427.75 ± 264.35 MET hours per week (MET-hr/wk) in 1991 to 245.99 ± 206.65 MET-hr/wk in 2011, with much steeper declines for women compared to men. For both genders, we found non-linear decreases in PA with age over time. Controlling for age effects, negative period effects on PA were observed in each survey year, and were substantial from 1993 to 2000 for males and from 1993 to 2011 for females. The interaction between survey year and age (P < 0.05) were observed from 2004 to 2011. Higher community urbanicity, vehicle ownership, TV and computer ownership, overweight and obese, higher education served as negative predictors. Bicycle ownership, bigger household size, non-professional jobs, being married and having more children (for women) were positive predictors of PA (P < 0.05). Furthermore, at any given age, individuals who were younger at baseline had higher mean PA compared with individuals older at baseline.ConclusionThis study followed a large cohort of adults over a significant portion of their lives. Strong age and secular trends were observed, resulting in an increasing number of participants who have or are likely to lower their PA levels. These trends suggest that tackling the rapid PA decline among its population is of high priority for China’s public health outlook as its population ages and continues to experience significant economic and environmental changes.

Higher Numbers of Pregnancies Associated With an Increased Prevalence of Gestational Diabetes Mellitus: Results From the Healthy Baby Cohort Study

“…27 This could be attributed to the reduced physical activity and muscle mass reported in older women. 28,29 Physical inactivity leads to a decline in glucose tolerance and an increase in fasting blood glucose, 30,31 while skeletal muscle mass was reported to negatively predict 2-hour plasma glucose levels in subjects with normal glucose tolerance. 32 These age-related changes in glucose metabolism would be exacerbated by pregnancy, which may explain the stronger association between the number of pregnancies and GDM among women aged ≥30 years.…”

The role of perceived environment, neighbourhood characteristics, and attitudes in walking behaviour: evidence from a rapidly developing city in China

“…Studies have shown that 18% of the population in developing countries are physically inactive (Dumith et al 2011). For instance, the average level of physical activity for adults in China has dropped by nearly 50% from 1991 to 2011 (Zang and Ng 2016), and almost 80% of its adolescents were reported having inadequate exercise (Chen et al 2014). In this context, walking has become a most sustainable form of physical activity in our daily lives, which enables people to interact with the environment in a more direct way due to its slow speed (Kamruzzaman et al 2016;Larrañaga et al 2016).…”

The Tsinghua–Lancet Commission on Healthy Cities in China: unlocking the power of cities for a healthy China

“…Work and domestic physical activity levels of adults fell by nearly half over 20 years (1991-2011) and were negatively associated with living in more urbanised areas. 106 Alarmingly, in urban adults participation in moderate or vigorous physical activity outside of work was as low as 7·9% in the International Collaborative Study of Cardiovascular Disease in Asia 107 done between 2000 and 2001.…”