Improved glycaemic control induced by evening activity breaks does not persist overnight amongst healthy adults: A randomized crossover trial.

AIMS: To compare the effects of 4 hours of laboratory-based regular activity breaks (RABs) and prolonged sitting (SIT) on subsequent 48-h free-living interstitial glucose levels in a group of healthy adults. MATERIALS AND METHODS: In this randomized crossover trial, participants completed two 4-h laboratory-based interventions commencing at ~5:00 pm: (1) SIT and (2) SIT interrupted with 3 min of body weight resistance exercise activity breaks every 30 min (RABs). Continuous glucose monitoring was performed during the intervention and for 48-h after, during which time participants returned to a free-living setting. RESULTS: Twenty-eight adults (female n = 20, mean ± SD age 25.5 ± 5.6 years, body mass index 29.2 ± 6.9 kg/m2) provided data for this analysis. During the intervention period, RABs lowered mean interstitial glucose by 8.3% (-0.47 mmol/L/4 h, 95% confidence interval [CI] -0.74 to -0.20; p = 0.001) and area under the curve (AUC) by 8.9% (-2.01 mmol/L/4 h, 95% CI -3.05 to -0.97; p < 0.001) compared to SIT. Measures of glycaemic variability were not significantly different during the intervention. There were no significant differences in mean glucose and AUC between conditions during the first nocturnal period and 24-h post intervention. When compared to SIT, RABs increased continuous overall net action of glucose at 1 h and SD glucose by 22% (0.18 mmol/L, 95% CI 0.03 to 0.29; p = 0.018) and 26% (95% CI 4.9 to 42.7; p = 0.019) in the first nocturnal period and by 10% (0.09 mmol/L, 95% CI 0.01, 0.17; p = 0.025) and 15% (95% CI 6.6 to 22.4; p = 0.001) in the 24-h post intervention period, respectively. CONCLUSION: Performing activity breaks in the evening results in acute reductions in interstitial glucose concentrations; however, the magnitude of these changes is not maintained overnight or into the following 48 hours.

Micronutrient status of New Zealand adolescent women consuming vegetarian and non-vegetarian diets.

BACKGROUND AND OBJECTIVES: Globally, there appears to be an ever-increasing interest in adopting a vegetarian diet. However, there are concerns that avoiding meat may increase the risk of anaemia and micronutrient deficiencies, especially for vulnerable populations, such as adolescent women. The objective of this study was to compare the micronutrient status of vegetarian and non-vegetarian adolescent women in New Zealand. METHODS AND STUDY DESIGN: Adolescent women aged 15-18 y were recruited from eight locations across New Zealand. Blood samples were analysed for: haemoglobin, serum ferritin, soluble transferrin receptor, zinc, selenium, retinol binding protein, folate, vitamin B-12, vitamin D and parathyroid hormone. RESULTS: Of the 182 participants who provided a blood sample, 15% self-identified as vegetarian (n=27). On average, vegetarians had 3.1% (95% CI -5.8 to -0.4, p=0.025) lower haemoglobin, and 8.3% (95%CI -14.1 to -2.1, p=0.004) lower selenium. In contrast, serum folate was 80.5% (95% CI 45.7 to 123.7, p<0.001) higher. The prevalence of zinc and selenium deficiency was higher among vegetarians (50% and 12%, respectively) than non-vegetarians (21%, and 2%, respectively). CONCLUSIONS: Adolescent vegetarian women may be at increased risk of deficiency of micronutrients commonly found in animal products, including zinc and selenium, and may benefit from following dietary practices that enhance micronutrient intake and absorption.

Feasibility and Pilot Outcomes of the Move More @ Work Intervention Designed to Encourage Employees to be Physically Active for 2 Minutes After Every 30 Minutes of Sitting.

OBJECTIVE: The aim of the study is to evaluate the feasibility of a workplace intervention supporting employees to interrupt sitting time with short bouts of activity (termed an opportunity to move [OTM]). METHODS: Using an interrupted time series design, 58 sedentary employees provided baseline assessments of physical activity, health, and work-related outcomes and completed the 12-week intervention. Assessments were repeated immediately and 12 weeks after intervention. Focus groups explored intervention acceptability. RESULTS: Accelerometer data showed no change in the number of OTMs taken before to after intervention, while participants self-reported 62-69% intervention adherence. Physical activity at work, productivity, and musculoskeletal health improved but cardiometabolic health and psychological well-being did not. Intervention components were viewed favorably (pending amendments), but taking an OTM every 30 minutes was not feasible. CONCLUSIONS: The Move More @ Work intervention has potential, but adaptations are required to increase adherence.

Breaking Up Evening Sitting with Resistance Activity Improves Postprandial Glycemic Response: A Randomized Crossover Study.

INTRODUCTION: Interrupting sedentary time during the day reduces postprandial glycemia (a risk factor for cardiometabolic disease). However, it is not known if benefits exist for postprandial glucose, insulin and triglyceride responses in the evening, and if these benefits differ by body mass index (BMI) category. METHODS: In a randomized crossover study, 30 participants (25.4 ± 5.4 yr old; BMI 18.5-24.9: n = 10, BMI 25-29.9: n = 10, BMI ≥30: n = 10) completed two intervention arms, beginning at ~1700 h: prolonged sitting for 4 h, and sitting with regular activity breaks of 3 min of resistance exercises every 30 min. Plasma glucose, insulin, and triglyceride concentrations were measured in response to two meals fed at baseline and 120 min. Four-hour incremental area under the curve was compared between interventions. Moderation by BMI status was explored. RESULTS: Overall, when compared with prolonged sitting, regular activity breaks lowered plasma glucose and insulin incremental area under the curve by 31.5% (95% confidence interval = -49.3% to -13.8%) and 26.6% (-39.6% to -9.9%), respectively. No significant differences were found for plasma triglyceride area under the curve. Interactions between BMI status and intervention was not statistically significant. CONCLUSIONS: Interventions that interrupt sedentary time in the evening may improve cardiometabolic health by some magnitude in all participants regardless of bodyweight.

Predicting height from ulna length for the determination of weight status in New Zealand adolescents: A cross-sectional study.

BACKGROUND: The measurement of height is crucial for weight status assessment. When standing height is difficult to measure, ulna length may offer a convenient and accurate surrogate of height measure. Adolescence is a period of accelerated linear growth; hence, the validation of age-specific equations that predict height from ulna length in adolescents is warranted. The present study aimed to develop and validate age- and sex-specific equations for predicting height from ulna length in New Zealand adolescents. METHODS: Height, weight and ulna length were measured in 364 adolescents (n = 110 males, n = 254 females) aged 15.0-18.8 years, who were enrolled in the SuNDiAL (Survey of Nutrition Dietary Assessment and Lifestyle) project, a cross-sectional survey performed in 2019 and 2020. Regression models were used to determine equations to predict height from ulna length. Agreement between measured and predicted height, body mass index (BMI) and BMI z-score was assessed with intra-class correlation coefficients (ICC) and Bland-Altman plots. Sensitivity and specificity were calculated for classifying obesity. RESULTS: Strong agreement was found between predicted and measured height (ICC = 0.78; mean difference = 0; 95% confidence interval = -0.5 to 0.5 cm) and BMI (ICC = 0.95; mean difference = 0; 95% confidence interval = -0.1 to 0.1 kg m-2 ). Predicted height was 88.1% accurate when classifiying weight status, showing high sensitivity (93.8%) and specificity (99.4%) for classifying obesity. CONCLUSIONS: Ulna length measurement can accurately estimate height and subsequently weight status in New Zealand adolescents aged 15-18 years.

Rationalisation of meat consumption in New Zealand adolescents.

OBJECTIVE: This study aimed to describe meat consumption rationalisation and relationships with meat consumption patterns and food choice motivations in New Zealand adolescents. DESIGN: This was a cross-sectional study of adolescents from high schools across New Zealand. Demographics, dietary habits, and motivations and attitudes towards food were assessed by online questionnaire and anthropometric measurements taken by researchers. The 4Ns questionnaire assessed meat consumption rationalisation with four subscales: 'Nice', 'Normal', 'Necessary' and 'Natural'. SETTING: Nineteen secondary schools from eight regions in New Zealand, with some purposive sampling of adolescent vegetarians in Otago, New Zealand. PARTICIPANTS: Questionnaires were completed by 385 non-vegetarian and vegetarian (self-identified) adolescents. RESULTS: A majority of non-vegetarian adolescents agreed that consuming meat was 'nice' (65 %), but fewer agreed that meat consumption was 'necessary' (51 %). Males agreed more strongly than females with all 4N subscales. High meat consumers were more likely to agree than to disagree that meat consumption was nice, normal, necessary and natural, and vegetarians tended to disagree with all rationalisations. Adolescent non-vegetarians whose food choice was motivated more by convenience, sensory appeal, price and familiarity tended to agree more with all 4N subscales, whereas adolescents motivated by animal welfare and environmental concerns were less likely to agree. CONCLUSIONS: To promote a reduction in meat consumption in adolescents, approaches will need to overcome beliefs that meat consumption is nice, normal, necessary and natural.

Protocol for a pilot trial to assess the feasibility of the Move More @ Work intervention to encourage employees to take the opportunity to move (be physically active) after every 30 min of sitting.

BACKGROUND: Prolonged sitting increases the risk of cardio-metabolic disease. Office-based employees are particularly susceptible to high rates of this sedentary behaviour during work hours. Laboratory studies indicate that regularly interrupting periods of prolonged sitting with short bouts (2 min) of physical activity can improve markers of cardio-metabolic health. This method of interrupting sitting time is yet to be tested in an occupational setting and may provide an alternative to providing sit-to-stand desks. Drawing on the Behaviour Change Wheel and evidence on the barriers and motivators to performing regular activity breaks, the Move More @ Work intervention was developed. The objectives of this pilot study are to examine the feasibility, and preliminary outcomes, of this intervention designed to encourage participants to perform 1-2 min of activity after every 30 min of continuous sitting throughout the work day. The study will inform if progress to a full effectiveness trial is warranted. METHODS: An interrupted time series design consisting of a 4-week baseline (control period), a 12-week intervention, and a 12-week follow-up will be utilised. At least 57 university employees who self-report spending > 5 h per day sitting at work on at least 3 days per week will be recruited to participate. The intervention consists of (1) a structured consultation with a Move More @ Work coach, containing a number of behaviour change techniques to create an individualised plan of how to incorporate the activity breaks into the working day, and (2) strategies to create a supportive workplace culture for performing the activity breaks. Feasibility will be assessed by recruitment and retention rates, and acceptability of the intervention. Pilot outcomes are the number of regular activity breaks taken during the workday, cardio-metabolic risk score and self-reported health, and work-related productivity outcomes. DISCUSSION: If the Move More @ Work intervention is shown to be feasible, acceptable, and shows evidence of effectiveness, this will provide justification for the progression to a full scale evaluation of the intervention. In the longer-term, this intervention may provide an alternative means of improving health outcomes through interrupting sedentary time than that offered by current sedentary behaviour interventions. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12620000354987 . Registered on 12 March 2020.

Using a 24 h Activity Recall (STAR-24) to Describe Activity in Adolescent Boys in New Zealand: Comparisons between a Sample Collected before, and a Sample Collected during the COVID-19 Lockdown.

BACKGROUND: Tools that assess all three components of 24 h movement guidelines (sleep, physical activity, and screen use) are scarce. Our objective was to use a newly developed Screen Time and Activity Recall (STAR-24) to demonstrate how this tool could be used to illustrate differences in time-use across the day between two independent samples of male adolescents collected before and during the COVID-19 lockdown. METHODS: Adolescent boys aged 15-18 years (n = 109) each completed the STAR-24 twice, n = 74 before lockdown and n = 35 during lockdown. RESULTS: During lockdown more than 50% of the sample reported gaming between 10 a.m. and 12 noon, transport was not reported as an activity, and activities of daily living spiked at mealtimes. Gaming and screen time were more prevalent in weekends than weekdays, with the highest prevalence of weekday screen use (before lockdown) occurring between 8 and 9 p.m. Differences in estimates of moderate-to-vigorous physical activity prior to and during lockdown (mean difference (95% CI); 21 (-9 to 51) min) and sleep (0.5 (-0.2 to 1.2) h) were small. Total and recreational screen time were higher during lockdown (2 h (0.7 to 3.3 h) and 48 min (-36 to 132 min), respectively). CONCLUSIONS: The STAR-24 holds promise as a single tool that assesses compliance with 24 h movement guidelines. This tool also allows clear illustration of how adolescent boys are using their time (instead of only providing summary measures), providing richer data to inform public health initiatives.

The Impact of Organised Sport, Physical Education and Active Commuting on Physical Activity in a Sample of New Zealand Adolescent Females.

BACKGROUND: The majority of adolescents do less physical activity than is recommended by the World Health Organization. Active commuting and participation in organised sport and/or physical education individually have been shown to increase physical activity in adolescents. However, how these domains impact physical activity both individually and in combination has yet to be investigated in a sample of New Zealand female adolescents from around the country. METHODS: Adolescent females aged 15-18 y (n = 111) were recruited from 13 schools across eight locations throughout New Zealand to participate in this cross-sectional study. Participants completed questions about active commuting, and participation in organised sport and physical education, before wearing an Actigraph GT3X (Actigraph, Pensacola, FL, USA) +24 h a day for seven consecutive days to determine time spent in total, MVPA and light physical activity. RESULTS: Active commuters accumulated 17 min/d (95% CI 8 to 26 min/d) more MVPA compared to those who did not. Those who participated in sport accumulated 45 min/d (95% CI 20 to 71 min/d) more light physical activity and 14 min/d (95% CI 5 to 23 min/d) more MVPA compared to those who did not. Participation in physical education did not seem to have a large impact on any component of physical activity. Participation in multiple domains of activity, e.g., active commuting and organised sport, was associated with higher accumulation of MVPA but not light activity. Conclusion Active commuting and sport both contribute a meaningful amount of daily MVPA. Sport participation has the potential to increase overall activity and displace sedentary behaviour. A combination of physical activity domains may be an important consideration when targeting ways to increase physical activity in adolescent females.

How Does Being Overweight Moderate Associations between Diet and Blood Pressure in Male Adolescents?

Diet is one of the strongest modifiable risk factors for hypertension. In this study, we described the associations between dietary factors and blood pressure; and explored how weight status moderated these associations in a sample of New Zealand male adolescents. We collected demographics information, anthropometric, blood pressure, and dietary data from 108 male adolescents (15-17 years old). Mixed effects and logistic regression models were used to estimate relationships between dietary variables, blood pressure, and hypertension. Moderation effects of overweight status on the relationship between hypertension and diet were explored through forest plots. One-third (36%) of the sample was classified as hypertensive. Fruit intake was related to significantly lower systolic (-2.4 mmHg, p = 0.005) and diastolic blood pressure (-3.9 mmHg, p = 0.001). Vegetable and milk intake was related to significantly lower diastolic blood pressure (-1.4 mmHg, p = 0.047) and (-2.2 mmHg, p = 0.003), respectively. In overweight participants, greater vegetable and milk, and lower meat intake appeared to reduce the odds of hypertension. Certain dietary factors may have more prominent effects on blood pressure depending on weight status.

The effects of prolonged sitting, prolonged standing, and activity breaks on vascular function, and postprandial glucose and insulin responses: A randomised crossover trial.

The objective of this study was to compare acute effects of prolonged sitting, prolonged standing and sitting interrupted with regular activity breaks on vascular function and postprandial glucose metabolism. In a randomized cross-over trial, 18 adults completed: 1. Prolonged Sitting; 2. Prolonged Standing and 3. Sitting with 2-min walking (5 km/h, 10% incline) every 30 min (Regular Activity Breaks). Flow mediated dilation (FMD) was measured in the popliteal artery at baseline and 6 h. Popliteal artery hemodynamics, and postprandial plasma glucose and insulin were measured over 6 h. Neither raw nor allometrically-scaled FMD showed an intervention effect (p = 0.285 and 0.159 respectively). Compared to Prolonged Sitting, Regular Activity Breaks increased blood flow (overall effect of intervention p<0.001; difference = 80%; 95% CI 34 to 125%; p = 0.001) and net shear rate (overall effect of intervention p<0.001; difference = 72%; 95% CI 30 to 114%; p = 0.001) at 60 min. These differences were then maintained for the entire 6 h. Prolonged Standing increased blood flow at 60 min only (overall effect of intervention p<0.001; difference = 62%; 95% CI 28 to 97%; p = 0.001). Regular Activity Breaks decreased insulin incremental area under the curve (iAUC) when compared to both Prolonged Sitting (overall effect of intervention P = 0.001; difference = 28%; 95% CI 14 to 38%; p<0.01) and Prolonged Standing (difference = 19%; 95% CI 4 to 32%, p = 0.015). There was no intervention effect on glucose iAUC or total AUC (p = 0.254 and 0.450, respectively). In normal-weight participants, Regular Activity Breaks induce increases in blood flow, shear stress and improvements in postprandial metabolism that are associated with beneficial adaptations. Physical activity and sedentary behaviour messages should perhaps focus more on the importance of frequent movement rather than simply replacing sitting with standing.

Physical Activity, Sedentary Behaviour and Sleep, and Their Association with BMI in a Sample of Adolescent Females in New Zealand.

Despite activity guidelines moving towards a 24-h focus, we have a poor understanding of the 24-h activity patterns of adolescents. Therefore, this study aims to describe the 24-h activity patterns of a sample of adolescent females and investigate the association with body mass index (BMI). Adolescent females aged 15-18 years (n = 119) were recruited across 13 schools in 8 locations throughout New Zealand. Actigraph GT3X+ accelerometers were worn 24-h a day for seven days and the output was used to identify time spent in each 24-h component (sleep, sedentary, light-intensity physical activity and moderate-to-vigorous intensity physical activity). In a 24-h period, adolescent females spent approximately half their time sedentary, one third sleeping and the remainder in light-intensity physical activity (15%) and moderate-to-vigorous intensity physical activity (5%). Higher BMI z-scores were associated with 16 min more time spent in light-intensity physical activity. Additionally, those with higher BMI were less likely to meet the sleep and physical activity guidelines for this age group. Compliance with the moderate-to-vigorous intensity physical activity guidelines, sleep guidelines, or both, was low, especially in those classified as overweight or obese. The association between BMI and light activity warrants further investigation.

Energy utilisation and postprandial responses during sitting interrupted by regular activity breaks.

Interrupting sedentary behaviour with regular activity breaks benefits glycaemic control; however, the influence of the energy utilised during these activity breaks on postprandial metabolic response is relatively unknown. Therefore, the aim of this study was to investigate whether the energy utilisation of regular (every 30 min) short (1 min 40 s or 2 min) activity breaks was associated with the lowering of postprandial glycaemia, insulinemia and lipidemia.Using separate data from two previously performed studies (ALPhA Study n = 65, age 25.7 (5.2) y, 40% male, BMI 23.6 (4.1) kg · m-2. ABPA study n = 35, age 25.1 (3.7) y, 31% male, BMI 23.4 (3.2) kg · m-2) we investigated the association between energy utilisation (measured by indirect calorimetry) and postprandial glucose, insulin and triglycerides during prolonged sitting, and regular activity breaks.Results.Mixed effects regression models indicated that energy utilisation was not consistently associated with postprandial glucose, insulin or triglyceride responses (p > 0.05 for all). Additionally, there was some indication that energy utilisation was obscuring (mildly suppressing) the effects of regular activity breaks on glucose, insulin and triglyceride iAUC.Conclusions.If energy utilisation does not mediate the association between regular activity breaks and postprandial glycaemic response, it is possible that it is the frequency of the activity breaks that is beneficial.

Device-Measured Sedentary Behavior Patterns in Office-Based University Employees.

OBJECTIVE: The aim of this study was to describe device-measured patterns of sedentary behavior in self-identified sedentary university employees. METHODS: Participants (n = 78) wore the ActiGraph GT3X+ and the activPAL3 for 7 days. Data from the ActiGraph were used to identify time in sedentary behavior, light-intensity, and moderate-to-vigorous physical activity. Data from the activPAL identified time sitting/lying, standing, and stepping. Breaks in sedentary time and prolonged sedentary bouts were described. RESULTS: During workdays, participants spent 65% to 79% of time sedentary, 16% in light-intensity physical activity, and 4% in moderate-to-vigorous physical activity, 76% of time was spent sitting/lying, 16% standing, and 8% stepping. Between 10 and 12 breaks in sedentary time were accumulated. CONCLUSION: Office-based university employees spend a high proportion of their time sedentary, but accumulate a high number of breaks. Whether these breaks are appropriate in timing, duration, and intensity to elicit health benefits seen in laboratory studies requires further investigation.

The Acute Metabolic and Vascular Impact of Interrupting Prolonged Sitting: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aim was to conduct a systematic review and meta-analysis analyzing the impact of up to 24 h of prolonged sitting on postprandial glucose, insulin and triglyceride responses, blood pressure and vascular function, in comparison to sitting interrupted with light- to moderate-intensity physical activity. METHODS: To be included, studies had to examine the impact of prolonged sitting lasting < 24 h in apparently healthy males or females of any age. Studies were identified from searches of the MEDLINE, CINAHL and SportDISCUS databases on July 6, 2016. Study quality was assessed using the Downs and Black Checklist; publication bias was assessed via funnel plot. RESULTS: Forty-four studies met the inclusion criteria for the systematic review; of these, 20 were included in the meta-analysis, which compared prolonged sitting to the effects of interrupting sitting with regular activity breaks on postprandial glucose, insulin and triglycerides. When compared to prolonged sitting, regular activity breaks lowered postprandial glucose (d = - 0.36, 95% confidence interval [CI] - 0.50 to - 0.21) and insulin (d = - 0.37, 95% CI - 0.53 to - 0.20), but not triglyceride responses (d = 0.06, 95% CI - 0.15 to 0.26). Subgroup analyses indicated reductions in postprandial triglyceride responses only occurred 12-16 h after the intervention. The magnitude of the reductions in glucose, insulin or triglyceride response was not modified by the intensity of the activity breaks, the macronutrient composition of the test meal, or the age or body mass index of participants. CONCLUSION: Prolonged sitting results in moderate elevations in postprandial glucose and insulin responses when compared to sitting interrupted with activity breaks. PROSPERO ID: CRD42015020907.

Interrupting Prolonged Sitting with Regular Activity Breaks does not Acutely Influence Appetite: A Randomised Controlled Trial.

Regular activity breaks increase energy expenditure; however, this may promote compensatory eating behaviour. The present study compared the effects of regular activity breaks and prolonged sitting on appetite. In a randomised, cross-over trial, 36 healthy adults (BMI (Body Mass Index) 23.9 kg/m² (S.D. = 3.9)) completed four, two-day interventions: two with prolonged sitting (SIT), and two with sitting and 2 min of walking every 30 min (RAB). Standardized meals were provided throughout the intervention, with an ad libitum meal at the end of Day 2. Appetite and satiety were assessed throughout both days of each intervention using five visual analogue scales. The five responses were combined into a single appetite response at each time point. The area under the appetite response curve (AUC) was calculated for each day. Intervention effects for appetite response AUC and ad libitum meal intake were tested using linear mixed models. Appetite AUC did not differ between interventions (standardised effect of RAB compared to SIT: Day 1: 0.11; 95% CI: -0.28, 0.06; p = 0.212; Day 2: 0.04; 95% CI: -0.15, 0.24; p = 0.648). There was no significant difference in energy consumed at the ad libitum lunch meal on Day 2 between RAB and SIT. Interrupting prolonged sitting with regular activity breaks does not acutely influence appetite or volume of food consumed, despite inferred increases in energy expenditure. Longer-term investigation into the effects of regular activity breaks on energy balance is warranted.

Sedentary Behavior and Body Weight and Composition in Adults: A Systematic Review and Meta-analysis of Prospective Studies.

BACKGROUND: The cumulative effect of too much sedentary behavior may contribute to weight gain and obesity. OBJECTIVE: The aim of this study was to conduct a systematic review and meta-analysis of prospective cohorts and randomized controlled studies to determine the association between sedentary behavior and body weight and obesity in adults. DATA SOURCES AND STUDY SELECTION: Relevant studies were identified from searches of the MEDLINE, Embase, AMED and PubMed databases up to May 2017, and by manual searches of in-text citations. Studies that evaluated the association in adults between sedentary behavior and body weight or obesity, while controlling for physical activity, were included. Overall, 31 publications met the eligibility criteria, including 23 prospective cohort studies with data that could be extracted for a quantitative meta-analysis, and a single randomized controlled trial. RESULTS: There were no significant associations between sedentary behavior and any measure of body weight or obesity, with the exception of waist circumference. For the latter outcome, over a 5-year follow-up period, each 1 h per day increase-from baseline to follow-up-in sedentary behavior was associated with a 0.02 mm [95% confidence interval (CI) 0.01-0.04; p = 0.001) increase in waist circumference. The odds ratio of becoming overweight or obese was 1.33 (95% CI 1.11-1.60; p = 0.001) in the highest compared with lowest categories of sedentary behavior. CONCLUSIONS: Meta-analysis of data from prospective cohort studies showed small, inconsistent and non-significant associations between sedentary behavior and body weight.

Regular activity breaks combined with physical activity improve postprandial plasma triglyceride, nonesterified fatty acid, and insulin responses in healthy, normal weight adults: A randomized crossover trial.

BACKGROUND: Compared with prolonged sitting, regular activity breaks immediately lower postprandial glucose and insulin, but not triglyceride responses. Postprandial triglycerides can be lowered by physical activity but the effect is often delayed by ∼12 to 24 hours. OBJECTIVE: The objective of the study was to determine whether regular activity breaks affect postprandial triglyceride response in a delayed manner similar to physical activity. METHODS: In a randomized crossover trial, 36 adults (body mass index 23.9 kg/m2 [standard deviation 3.9]) completed four 2-day interventions: (1) prolonged sitting (SIT); (2) prolonged sitting with 30 minutes of continuous walking (60% VO2max), at the end of Day 1 (SIT + PAD1); (3) Sitting with 2 minutes of walking (60% VO2max) every 30 minutes (RAB); (4) A combination of the continuous walking and regular activity breaks in 2 and 3 above (RAB + PAD1). Postprandial plasma triglyceride, nonesterified fatty acids, glucose, and insulin responses were measured in venous blood over 5 hours on Day 2. RESULTS: Compared with SIT, both RAB (difference: -43.61 mg/dL·5 hours; 95% confidence interval [CI] -83.66 to -2.67; P = .035) and RAB + PAD1 (-65.86 mg/dL·5 hours; 95% CI -112.14 to -19.58; P = .005) attenuated triglyceride total area under the curve (tAUC). RAB + PAD1 produced the greatest reductions in insulin tAUC (-23%; 95% CI -12% to -31%; P < .001), whereas RAB resulted in the largest increase in nonesterified fatty acids (tAUC, 10.08 mg/dL·5 hours; 95% CI 5.60-14.84; P < .001). There was no effect on glucose tAUC (P = .290). CONCLUSIONS: Postprandial triglyceride response is attenuated by regular activity breaks, when measured ∼24 hours after breaks begin. Combining regular activity breaks with 30 minutes of continuous walking further improves insulinemic and lipidemic responses.

Postprandial Metabolic Effects of Accelerometer Measured Spontaneous Low-Level Activity.

BACKGROUND: Interrupting sedentary time induces improvements in glucose metabolism; however, it is unclear how much activity is required to reduce the negative effects of prolonged sitting. METHODS: Sixty-six participants sat continuously for 9 hours except for required bathroom breaks. Participants were fed meal replacement beverages at 60, 240 and 420 min. Blood samples were obtained hourly for 9 hours, with additional samples collected 30 and 45 min after each feeding. Responses were calculated as incremental area under the curve (iAUC) for plasma glucose, insulin and triglyceride. Participants wore a triaxial accelerometer and a heart rate monitor. Energy expenditure was estimated using indirect calorimetry. RESULTS: After controlling for age, sex and BMI, every 100 count increase in accelerometer derived total movement was associated with a 0.06 mmol·L-1·9 hours decrease in glucose iAUC (95% CI 0.004-0.1; P = .035), but not associated with changes in insulin or triglyceride iAUC. Every 1 bpm increase in mean heart rate was associated with a 0.76 mmol·L-1·9 hours increase in triglyceride iAUC (95% CI 0.13-1.38). CONCLUSION: Accelerometer measured movement during periods of prolonged sitting can result in minor improvements in postprandial glucose metabolism, but not lipid metabolism.