1.
Objective measurement of physical activity and sedentary behavior among South Asian adults: A systematic review.
Mahmood, B, Tang, TS, Afshar, R, Ashe, MC
PloS one. 2020;(8):e0236573
Abstract
BACKGROUND South Asians are one of the fastest growing ethnic groups in western countries with a high incidence of chronic diseases like metabolic syndrome and cardiovascular disease occurring at younger ages and lower body weight compared with white Europeans. Physically active lifestyle and reduced sedentary time are modifiable risk factors that can decrease burden of chronic diseases. Population-level surveys based on self-report show South Asians engage in low levels of physical activity. Because of known limitations with self-report data, we aimed to synthesize available evidence to generate a physical activity /sedentary time profile of South Asians from studies using accelerometry. METHODS We systematically searched Medline, EMBASE, CINAHL, PsycINFO, and SportDiscus. We included studies applying accelerometry to measure physical activity /sedentary time under free-living. Studies with an exclusive focus on drugs or including participants with health conditions/physical disability, and special populations (athletes/pregnant women) were excluded. Two authors independently adjudicated inclusion of citations at title/abstract and full text. We applied a standardized data abstraction form to extract relevant data. We evaluated methodological quality using Newcastle Ottawa Quality Assessment Scale. Due to variability and inconsistencies in measurement and reporting of physical activity /sedentary time, we only provide a narrative synthesis. FINDINGS We identified only 14 studies(n = 1,338). Despite using similar accelerometry assumptions, we noted variability in reported outcomes for physical activity and sedentary time. Sedentary time ranged from 482(98) to 587 min/day. Mean light physical activity ranged from 211.69(67. 38) to 574(227) min/day. Moderate to vigorous physical activity among South Asian women ranged from 17-41 min/day and among men, 32-43 min/day. CONCLUSION South Asians exhibited higher levels of physical activity when compared to the Canadian population level survey but not when compared to the American population level survey. Overall, fewer studies, and small sample sizes led to considerable variability limiting any effective comparisons. Results highlight the importance of conducting methodologically robust studies based on random sampling to advance the field, and to capture true levels of sedentary time and physical activity in the South Asian population.
2.
Sedentary time in children: influence of accelerometer processing on health relations.
Atkin, AJ, Ekelund, U, Møller, NC, Froberg, K, Sardinha, LB, Andersen, LB, Brage, S
Medicine and science in sports and exercise. 2013;(6):1097-104
Abstract
PURPOSE Accelerometry is increasingly being used to assess sedentary time in epidemiological studies, yet the most appropriate means of processing these data remains uncertain. This cross-sectional study examined the influence of selected accelerometer cut points and nonwear criteria on associations of sedentary time with adiposity and clustered metabolic risk. METHODS Data were from the European Youth Heart Study, which included assessment of sedentary time by accelerometer. Sixteen sedentary time variables were constructed based on combinations of frequently used cut points (100, 500, 800, and 1100 counts per minute) and nonwear criteria (10-, 20-, 60-, and 100-min consecutive zeros). Adiposity was assessed by sum of four skinfold thickness measures. A clustered metabolic risk score was calculated as the mean of standardized metabolic syndrome components, including blood pressure, insulin resistance, and inverted fasting HDL-cholesterol. Analyses were conducted using multilevel cross-sectional time series regression, adjusted for overall physical activity (accelerometer counts per minute). Meta-analysis was used to obtain pooled estimates of the exposure-outcome association over all processing protocols; meta-regression was used to determine the influence of nonwear and cut point protocol on observed associations. RESULTS Sedentary time follows a power law with cut point (exponent = 0.27) and zero string (exponent = 0.03), and it was positively associated with clustered metabolic risk (β = 0.0051; 95% confidence interval = 0.0018-0.0085). The association was moderated by cut point, with higher cut points typically producing stronger associations. No significant association between sedentary time and adiposity was observed. CONCLUSIONS The choice of accelerometer cut point may moderate the association between sedentary time and clustered metabolic risk, suggesting that direct comparisons of associations between studies using different cut points must be made with caution.