Objective Measures Of Sedentary Behaviour Research Articles

Objective measurement of sedentary behavior: impact of non-wear time rules on changes in sedentary time.

BackgroundAccelerometry non-wear time rules might affect sedentary time, and the associations with health outcomes such as adiposity. However, the exact effect of different non-wear time rules on sedentary time and reported changes in sedentary time is unknown. This study evaluated the effect of different accelerometry non-wear time rules on sedentary time and changes in sedentary time from age 9–12 years.MethodsAccelerometry data were collected as part of the Gateshead Millennium Birth Cohort study. Participants were 9.3 (±0.4) years at baseline (n = 517) and 12.5 (±0.3) years at follow-up (n = 440). Sedentary time was defined using an accelerometry cut-point of 25 counts per 15 s. Non-wear time was defined using manual data reduction (the reference method) and 10 min, 20 min and 60 min consecutive zeros. Differences between methods were analyzed using repeated measures ANOVA with Bonferroni post-hoc analyses.ResultsMean daily sedentary time at age 9 ranged from 364 min per day to 426 min using the 10 min and 60 min rule, respectively (p < 0.05). At 12 years, mean daily sedentary times ranged from 424 min to 518 min (p < 0.05). Mean changes in daily sedentary time over the three years ranged from 60 min to 93 min using the 10 min and 60 min rule, respectively (p < 0.05). When adjusting for wear time, differences in average sedentary time between methods decreased from 62 min to 27 min (age 9), 95 min to 32 min (age 12) and 33 min to 10 min (changes between 9 to 12 years).ConclusionsUsing different non-wear time rules results in significant differences in daily sedentary time and changes in sedentary time. Correcting for wear time appears to be a reasonable approach to limiting these differences and may improve comparability between future studies. Using the 20 min rule, while correcting for wear time, provided the most accurate estimates of sedentary time and changes in sedentary time, compared to the manual reference in 9–12 year-olds.

Identifying associations between sedentary time and cardio-metabolic risk factors in working adults using objective and subjective measures: a cross-sectional analysis.

BackgroundSedentary behavior has been reported to be associated with metabolic and vascular health independent of moderate-to-vigorous physical activity (MVPA). In order to select appropriate options to measure sedentary behavior in practice and research settings, it is worthwhile to characterize the extent to which objective and subjective measures of sedentary behavior quantify adverse health risks in the same population. This cross-sectional analysis compared accelerometer-derived and self-reported sedentary time to identify their association with cardio-metabolic risk factors.MethodsCross-sectional analysis was conducted using data from 661 Japanese workers (145 women) aged 20–64 years. Participants wore a tri-axial accelerometer device for 10 consecutive days and completed the Japan Atherosclerosis Longitudinal Study Physical Activity Questionnaire. Data on body mass index, waist circumference, resting blood pressure, triglycerides, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, total:HDL cholesterol ratio, blood glucose, and glycosylated hemoglobin (HbA1c) were obtained from annual health examinations.ResultsBoth accelerometer-derived and self-reported sedentary time were deleteriously associated with triglycerides, HDL-cholesterol, total:HDL ratio, and HbA1c after adjustment for potential confounders including MVPA. There were no significant differences in regression coefficients between the two measures. Thus, the magnitude of the associations of both measures with cardio-metabolic risk factors was similar, despite poor agreement between them. Occupational sedentary time was correlated with both measures of total sedentary time, and more consistently associated with cardio-metabolic risk factors than sedentary leisure time.ConclusionsBoth accelerometer and self-report measurements are similarly associated with cardio-metabolic risk factors in a Japanese working adult population. Subjective and objective measures of sedentary behaviors appear to capture different aspects of behaviors. Further efforts to establish data processing methods integrating objective and subjective measures are needed to more effectively assess sedentary time’s relationship to health outcomes.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2458-14-1307) contains supplementary material, which is available to authorized users.

Abstract P128: A New Device for Objective Measurement of Sedentary Behavior

Objective measurement of sedentary behavior with accelerometers is an important part of epidemiological research. Unfortunately, the definition of sedentary behavior includes both “sitting and low levels of energy expenditure”, which are not usually measured by popular activity monitors. Currently, there is only one research device (ActivPAL) that can objectively measure both body posture and activity for sedentary behavior classification. The purpose of this study was to compare the Lumoback device, a commercial accelerometer-based posture monitor, for sedentary measurement during daily activities to the ActivPAL. The Lumoback also has real-time feedback delivered to the user through their mobile device, which may prove to be instrumental in sedentary intervention research. Subjects (N=33) wore the Lumoback and ActivPAL devices simultaneously during waking hours while continuing with their normal activity patterns. Linear regression showed good correlation between sitting minutes (R2=0.89, p &lt; 0.001) and standing minutes (R2=0.86, p &lt; 0.001) from the devices. There was no significant difference (p &gt; 0.05) between the seconds of sedentary behavior measured with the lumoback and seconds sitting/lying measured with the ActivPAL. The lumoback posture monitor was similar to the ActivPAL for measurement of sedentary behavior, and could be used to measure sedentary behavior over the course of a waking day.

IDEEA activity monitor: validity of activity recognition for lying, reclining, sitting and standing

Recent evidence demonstrates the independent negative effects of sedentary behavior on health, but there are few objective measures of sedentary behavior. Most instruments measure physical activity and are not validated as measures of sedentary behavior. The purpose of this study was to evaluate the validity of the IDEEA system's measures of sedentary and low-intensity physical activities: lying, reclining, sitting and standing. Thirty subjects, 14 men and 16 women, aged 23 to 77 years, body mass index (BMI) between 18 to 34 kg/m(2), participated in the study. IDEEA measures were compared to direct observation for 27 activities: 10 lying in bed, 3 lying on a sofa, 1 reclining in a lawn chair, 10 sitting and 3 standing. Two measures are reported, the percentage of activities accurately identified and the percentage of monitored time that was accurately labeled by the IDEEA system for all subjects. A total of 91.6% of all observed activities were accurately identified and 92.4% of the total monitored time was accurately labeled. The IDEEA system did not accurately differentiate between lying and reclining so the two activities were combined for calculating accuracy. Using this approach the IDEEA system accurately identified 96% of sitting activities for a total of 97% of the monitored sitting time, 99% and 99% for standing, 87% and 88% for lying in bed, 87% and 88% for lying on the sofa, and 83% and 83% for reclining on a lawn chair. We conclude that the IDEEA system accurately recognizes sitting and standing positions, but it is less accurate in identifying lying and reclining positions. We recommend combining the lying and reclining activities to improve accuracy. The IDEEA system enables researchers to monitor lying, reclining, sitting and standing with a reasonable level of accuracy and has the potential to advance the science of sedentary behaviors and low-intensity physical activities.

Is Sitting Time a Strong Predictor of Weight Gain?

The current review aimed to examine the evidence on prospective associations between sedentary behavior (i.e., sitting time) and weight gain. Prospective studies published between January 2010 and August 2012 were identified from searches in the Medline databases. In total 13 studies (seven in adolescents and six in adults) examining the prospective association between sedentary behavior and any measure of weight gain met inclusion criteria. In adolescents, mixed evidence was observed for a positive association between sedentary behavior at baseline and weight gain at follow-up. In adults, there was insufficient evidence that sedentary time at baseline was a strong predictor of weight gain at follow-up. The majority of the included studies used self- or parent-reported sedentary time which can be affected by social desirability and recall bias. Marked heterogeneity in study populations, exposure and outcome measures precluded a quantitative meta-analysis. Failure to appropriately adjust the results for baseline measures of the outcome particularly in the studies in children and adolescents may partly explain the observations. Therefore, firm conclusions whether prolonged sitting time predict weight gain in young people and adults is currently not possible. High-quality studies using repeated objective measures of sedentary behavior is warranted to establish a causal association.

Sedentary behavior: target for change, challenge to assess.

Sedentary behavior is not a new topic, but trying to examine the direct links between sedentary behavior and health outcomes, independent of time spent in moderate- and vigorous-intensity physical activity, is a relatively new addition to the relationships between physical activity and health. Defining sedentary behavior as a risk factor and target for intervention opens up novel avenues for disease prevention and health promotion. The relationship between sedentary behavior and obesity is complex and not well understood, but the increased risk of disease due to sedentary behavior may be even greater in obese patients. Objective measurement of sedentary behavior is an important link in being able to understand the real effects of being sedentary, and a few measurement devices are described. Interventions targeting sedentary behavior should reduce total sedentary time, break long bouts of sitting with intermittent activity and encourage light-intensity activity throughout the day. New technologies can both measure and deliver an intervention aimed at reducing sitting time, the most common category of sedentary behavior. An optimal activity profile will include minimal amounts of sedentary behavior, in addition to regular physical activity and healthy sleep patterns.

Sedentary behaviour and cardiovascular disease: a review of prospective studies

Current estimates from objective accelerometer data suggest that American adults are sedentary for ∼7.7 h/day. Historically, sedentary behaviour was conceptualized as one end of the physical activity spectrum but is increasingly being viewed as a behaviour distinct from physical activity. Prospective studies examining the associations between screen time (watching television, watching videos and using a computer) and sitting time and fatal and non-fatal cardiovascular disease (CVD) were identified. These prospective studies relied on self-reported sedentary behaviour. The majority of prospective studies of screen time and sitting time has shown that greater sedentary time is associated with an increased risk of fatal and non-fatal CVD. Compared with the lowest levels of sedentary time, risk estimates ranged up to 1.68 for the highest level of sitting time and 2.25 for the highest level of screen time after adjustment for a series of covariates, including measures of physical activity. For six studies of screen time and CVD, the summary hazard ratio per 2-h increase was 1.17 (95% CI: 1.13-1.20). For two studies of sitting time, the summary hazard ratio per 2-h increase was 1.05 (95% CI: 1.01-1.09). Future prospective studies using more objective measures of sedentary behaviour might prove helpful in quantifying better the risk between sedentary behaviour and CVD morbidity and mortality. This budding science may better shape future guideline development as well as clinical and public health interventions to reduce the amount of sedentary behaviour in modern societies.

Cardiorespiratory fitness, weight status and objectively measured sedentary behaviour and physical activity in rural and urban Portuguese adolescents

Relationships among weight status (body mass index [BMI]), cardiorespiratory fitness (CRF) and objective measures of sedentary behaviour and physical activity (PA) were considered in a cross-sectional sample of Portuguese adolescents. The sample included 362 youth aged 13-16 years (165 males, 197 females) from urban and rural regions of the Portuguese midlands. CRF was assessed with the 20-m shuttle-run test. An uniaxial accelerometer was used to obtain five consecutive days of activity behaviours including time being sedentary. Pearson correlations and logistic regression analysis were used to examine relationships among variables. Rural adolescents were less active than their urban peers over the weekend. Both rural and urban youth with higher levels of CRF had a lower relative risk of being overweight/obese. The observations indicate important associations between weight status and CRF in both rural and urban Portuguese adolescents. In addition, place of residence has an important impact on weight status of this sample of adolescents.

Sedentary Behavior, Adiposity, and Cardiovascular Risk Factors in Adolescents. The AFINOS Study

To investigate the association between objective measures of sedentary behavior and cardiovascular risk factors (CRFs) in adolescents. A secondary aim was to evaluate the degree of association between overall and abdominal adiposity and CRFs. This cross-sectional study involved 210 adolescents aged 13-17 years. Measurements were made of the sum of the skinfold thicknesses at six locations (sum6), waist circumference (WC), systolic (SBP) and diastolic blood pressure (DBP), glucose, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and apolipoproteins A-1 and B-100. A CRF score was calculated from the mean arterial pressure (MAP) and TG, HDL-C and glucose levels. Sedentary behavior was assessed over 7 days using an accelerometer. Participants were divided into tertiles according to sedentary behavior and into low and high levels of overall (sum6) and abdominal (WC) adiposity. Adolescents with a high level of sedentary behavior had less favorable SBP, TG and glucose levels and CRF scores. Adolescents with a high level of overall adiposity demonstrated significant differences in five of the 11 variables analyzed (i.e. DBP, LDL-C, TC, apolipoprotein B-100 and CRF score), while adolescents with a high level of abdominal adiposity had differences in eight (i.e. SBP, MAP, HDL-C, LDL-C, TG, TC, apolipoprotein B-100 and CRF score). Adolescents with high levels of both overall and abdominal adiposity and sedentary behavior had the least favorable CRF scores. Sedentary behavior was associated with CRFs in adolescents, especially in obese adolescents. Abdominal adiposity seemed to play a more significant role in the development of CRFs than overall adiposity.

Novel Strategies to Promote Children’s Physical Activities and Reduce Sedentary Behavior

Physical activity and sedentary behavior (performed primarily while sitting) play a key role in the current and future health of young people. Most health evidence and intervention strategies targeting reductions in children's sedentary behavior have focused on television viewing, with mixed evidence as to the effectiveness of these strategies and of the importance of television viewing for children's health. Evidence from studies with adults using objective measures of sedentary behavior suggests that accumulated sedentary time is independently associated with metabolic health; importantly, emerging evidence suggests that the manner in which the sedentary behavior is accrued (ie, frequency of interruptions to time spent sedentary) may also have independent effects on health. Potential novel intervention approaches to reduce children's sedentary time include activity breaks during class time at school, delivery of active lessons and homework, and changes to the classroom environment. Further evidence of the importance of sedentary time (both total accumulation and frequency of interruptions) on children's health is required. Future studies should assess the effectiveness of interventions targeting organizational and pedagogical changes in schools as well as using homework to engage with families in more active ways.