Sedentary Time Bouts Research Articles

Sedentary behaviour patterns and carotid intima-media thickness in Spanish healthy adult population

ObjectiveThe aim of this study was to analyze the association between sedentary behaviour, as assessed by an accelerometer, and mean carotid intima-media thickness (IMT). MethodsThe study included 263 healthy subjects belonging to the EVIDENT study (59.3% women). Carotid IMT was measured by carotid ultrasonography. Sedentary behaviour was measured objectively over 7 days using ActiGraph accelerometers. Thresholds of 10 consecutive minutes were used to establish sedentary bouts, and assess the number (n/day), and length ≥10 min (min/day). ResultsTotal sedentary time and sedentary time in bouts ≥10 min was higher in participants with a larger mean carotid IMT (>P75). Otherwise, this sedentary time in bouts ≥10 min parameter was weakly associated with augmented carotid IMT injury in the logistic regression model. ConclusionTotal sedentary time and sedentary time in bouts ≥10 min, as assessed by accelerometer, was positively but weakly associated with carotid IMT. Equally, this sedentary time in bouts ≥10 min was associated with carotid injury, but disappears after adjusting for potential confounders. These findings support that reducing sedentary time and increasing breaks in bouts of sedentary time might represent a useful additional strategy in the cardiovascular disease prevention. Trial RegistrationClinical Trials.gov Identifier: NCT01083082.

Bone architecture and strength in the growing skeleton: the role of sedentary time.

Today's youths spend close to 60% of their waking hours in sedentary activities; however, we know little about the potentially deleterious effects of sedentary time on bone health during this key period of growth and development. Thus, our objective was to determine whether sedentary time is associated with bone architecture, mineral density, and strength in children, adolescents, and young adults. We used high-resolution peripheral quantitative computed tomography (Scanco Medical) to measure bone architecture (trabecular and cortical microstructure and bone macrostructure) and cortical and total bone mineral density (BMD) at the distal tibia (8% site) in 154 males and 174 females (9-20 yr) who were participants in the University of British Columbia Healthy Bones III study. We applied finite element analysis to high-resolution peripheral quantitative computed tomography scans to estimate bone strength. We assessed self-reported screen time in all participants using a questionnaire and sedentary time (volume and patterns) in a subsample of participants with valid accelerometry data (89 males and 117 females; ActiGraph GT1M). We fit sex-specific univariate multivariable regression models, controlling for muscle cross-sectional area, limb length, maturity, ethnicity, dietary calcium, and physical activity. We did not observe independent effect of screen time on bone architecture, BMD, or strength in either sex (P > 0.05). Likewise, when adjusted for muscle cross-sectional area, limb length, maturity, ethnicity, dietary calcium, and physical activity, accelerometry-derived volume of sedentary time and breaks in bouts of sedentary time were not a determinant of bone architecture, BMD, or strength in either sex (P > 0.05). Further study is warranted to determine whether the lack of association between sedentary time and bone architecture, BMD, and strength at the distal tibia is also present at other skeletal sites.

Occurrence and duration of various operational definitions of sedentary bouts and cross-sectional associations with cardiometabolic health indicators: The ENERGY-project

ObjectiveThis study examined the occurrence and duration of sedentary bouts and explored the cross-sectional association with health indicators in children applying various operational definitions of sedentary bouts. MethodsAccelerometer data of 647 children (10–13 years old) were collected in five European countries. We analyzed sedentary time (<100cpm) accumulated in bouts of at least 5, 10, 20 or 30min based on four operational definitions, allowing 0, 30 or 60s ≥100cpm within bouts. Health indicators included anthropometrics (i.e. waist circumference and body mass index (BMI)) and in a subsample from two European countries (n=112) fasting capillary blood levels of glucose, C-peptide, high-density- and low-density cholesterol, and triglycerides. Data collection took place from March to July 2010. Associations were adjusted for age, gender, moderate-to-vigorous physical activity, total wear time and country. ResultsOccurrence of sedentary bouts varied largely between the various definitions. Children spent most of their sedentary time in bouts of ≥5min while bouts of ≥20min were rare. Linear regression analysis revealed few significant associations of sedentary time accumulated in bouts of ≥5–30min with health indicators. Moreover, we found that more associations became significant when allowing no tolerance time within sedentary bouts. ConclusionDespite a few significant associations, we found no convincing evidence for an association between sedentary time accumulated in bouts and health indicators in 10–13 year old children.

Changing the sedentary time and physical activity trajectories of obese adolescents: Results from the CAFAP controlled clinical trial

Introduction: Adolescents are typically on trajectories of increasing sedentary timeanddecreasingmoderate/vigorousphysical activity. Overweight and obese adolescents may have poorer activity profiles than normal weight adolescents and therefore be at increased risk of activity-related physical and mental health problems. As activity behaviours tend to track from adolescence to adulthood, altering adolescent activity trajectories is likely to have long-term health consequences. This study aimed to evaluate the immediate and 12 month post-intervention effectiveness of an intervention focused on changing the sedentary and physical activity behaviours of obese adolescents. Methods: Sixty nine adolescents aged 14.1 (SD 1.6) years participated in awithin-subjects staggered-entrywaitlist controlled trial ofCurtinUniversity’sActivity, FoodandAttitudesProgram(CAFAP). CAFAP involved an 8 week intensive multi-disciplinary familybased community intervention with tapered text message and phone support for 12 months. Sedentary time and light, moderate and vigorous activity were measured using Actical accelerometers worn on the hip for a week. Fifty six participants provided adequate accelerometer data in at least two assessments and were included in linear mixed model analysis. Activity profile patterns were assessed with Exposure Variation Analysis. Results: On entry to the study adolescents were sedentary for 70.3% of their awake wear day, with 25.4% spent in light activity, 4.2% in moderate activity and just 0.2% spent in vigorous activity. 28.1% of their wear day was spent in bouts of sedentary time of at least 30min duration, with 9.8% spent in sedentary bouts of 60min ormore. During the control period adolescents showed trajectories of increasing daily sedentary time (mean 532.3 [SE 3.3] to 548.2 [3.7], p=0.003) and decreasing daily light activity (199.7 [2.7] to 186.4 [3.5], p=0.007) with decreasing trends for moderate (31.1 [1.3] to 29.4 [1.1], p=0.147) and vigorous (1.5 [0.2] to 1.3 [0.2], p=0.470) activity. During the intervention period these trajectories were reversedwithmonthly rates of change showing a decrease for sedentary time (−5.1 [95% CI −11.0, 0.8]) and an increase for moderate physical activity (1.8 [−0.04, 3.6]). Sedentary time and light, moderate and vigorous activity levels remained stable over the 12month maintenance period. There were no significant reductions in prolonged bouts of sedentary time following the intervention. Discussion: The CAFAP intervention was effective in changing the sedentary time and physical activity trajectories of obese adolescents suggesting behavior focused interventions have the potential to create long-term health changes. However trajectories of prolonged sedentary time were not changed in the intervention and thus further development of interventions targeting the pattern of sedentary behaviour is required.

Abstract T P106: Sedentary Time During the Acute Hospital Stay is Associated With Functional Performance

Purpose: A few studies have been conducted during in-patient rehabilitation to describe physical activity (PA) levels. Most have been observational and conducted at various time intervals during the day. These studies have shown that during in-patient rehabilitation, stroke survivors participate in minimal therapy as well as spend the majority of their day sedentary. To our knowledge no studies have characterized PA during the acute hospital stay. The purpose of this study was to objectively assess PA levels using tri-axial accelerometers during the acute hospital stay. We will determine whether the duration of sedentary bouts are associated with functional performance at discharge. We hypothesized that shorter bouts of sedentary time will moderately associated with greater performance on walking and functional ability at discharge. Methods: Twenty-nine individuals (14 males; average age of 59.17 ± 11.6 years) were enrolled into the study within 48 hours of hospital admission with acute stroke. Tri-axial accelerometers were placed bilaterally on the ankles to monitor activity 24 hours per day. Functional assessments were conducted at baseline and prior to discharge. Walking was assessed using the Timed-Up and Go (TUG) and Six Minute Walk Test (6MWT). Activities of daily living (ADLs) were assessed using the Physical Performance Test (PPT). Results: During the acute hospital stay, the average percent time spent in sedentary, light, moderate and vigorous activities was 94.8 ± 3.2%, 4.4 ± 2.1%, 0.5 ± 0.5%, and 0.1 ± 0.3%, respectively. For individuals with functional testing at baseline and discharge (n = 17), average length of sedentary bouts per day was significantly related to 6MWT (r = -0.61, p &lt; 0.006) and PPT (r = -0.76, p &lt; 0.001) at discharge, but not TUG (r = 0.24, p &lt; 0.37) even when controlling for baseline performance. Conclusion: Stroke patients spend the majority of the stroke hospital stay sedentary. Stroke patients who had shorter bouts of sedentary time during the hospital stay showed greater performance in the 6-MWT and PPT. Acute stroke patients would benefit from decreasing sedentary time during the acute hospital stay.

Longitudinal levels and bouts of sedentary time among adolescent girls

BackgroundAdolescent girls are one of the most sedentary demographic groups. A better understanding of their accumulation of sedentary time is needed to inform future interventions. The purpose of this study was to examine the longitudinal levels and bouts of objectively measured sedentary time accumulated during different days of the week and periods of the weekday among a large sample of adolescent girls.MethodsThe results are based on 655 adolescent girls from the Girls in Sport Intervention and Research Project. Levels and bouts of sedentary time were derived from accelerometer data collected at baseline and 18-month follow-up. Total, weekday, weekend, school (i.e., morning bell to afternoon bell), after school (i.e., afternoon bell to 19:00), and evening (i.e. 19:01 to 23:59) sedentary time levels and bouts were calculated. Repeated-measures ANCOVAs were conducted to examine differences in sedentary time levels and bouts between days and time periods after adjusting for wear time, accelerometer model, and intervention group.ResultsCross-sectional analyses revealed that levels and bouts of sedentary time were higher on weekdays compared to weekend days at baseline. Similar trends were observed at follow-up. In addition, percentage of wear time spent sedentary and bouts/hr of sedentary time were highest in the evening compared to the school and after school periods at both baseline and follow-up. Longitudinal analyses revealed that levels and bouts of sedentary time were higher at follow-up compared to baseline across the different days of the week and periods of the weekday examined, with the biggest increase (15%) occurring in the school period.ConclusionsFuture interventions targeting sedentary time among adolescent girls should consider developing strategies to reduce and break up prolonged sedentary time during the school day and in the evening.