Daniel Paul Bailey

Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not

OBJECTIVES To explore the effects of breaking up prolonged sitting time with standing or light-intensity walking on a range of cardiometabolic risk markers. DESIGN A randomised three-period, three-treatment acute crossover trial. METHODS Ten non-obese adults took part in three trials: (1) uninterrupted sitting; (2) seated with 2-min bouts of standing every 20 min; and (3) seated with 2-min bouts of light-intensity walking every 20 min. Two standardised test drinks (total 80.3 carbohydrate, 50 g fat) were provided after an initial 1-h period of uninterrupted sitting. Plasma glucose and blood pressure were assessed hourly to calculate area under the curve. Total cholesterol, HDL, and triglycerides were assessed at baseline and 5-h. ANOVAs were used to explore between-trial differences. RESULTS Glucose area under the curve was lower in the activity-break condition compared to the uninterrupted sitting and standing-break conditions: mean area under the curve 18.5 (95% CI 17, 20), 22.0 (20.5, 23.5), and 22.2 (20.7, 23.7) mmol L/5-h, respectively, p<0.001; no difference between uninterrupted sitting and standing-break conditions (p>0.05). Systolic and diastolic blood pressure area under the curve did not differ significantly between conditions, nor did responses in lipid parameters (p>0.05). CONCLUSIONS This study suggests that interrupting sitting time with frequent brief bouts of light-intensity activity, but not standing, imparts beneficial postprandial responses that may enhance cardiometabolic health. These findings may have importance in the design of effective interventions to reduce cardiometabolic disease risk.

Cardiorespiratory Fitness Is Associated with Hard and Light Intensity Physical Activity but Not Time Spent Sedentary in 10–14 Year Old Schoolchildren: The HAPPY Study

Background Sedentary behaviour is a major risk factor for developing chronic diseases and is associated with low cardiorespiratory fitness in adults. It remains unclear how sedentary behaviour and different physical activity subcomponents are related to cardiorespiratory fitness in children. The purpose of this study was to assess how sedentary behaviour and different physical activity subcomponents are associated with 10–14 year-old schoolchildrens cardiorespiratory fitness. Methods 135 schoolchildren (81 girls, 12±1 year) completed 7-day minute-by-minute habitual physical activity monitoring using triaxial accelerometers and undertook a maximal cardiorespiratory fitness test. Results After controlling for sex, age, ethnicity, socioeconomic status and total wear time, light physical activity (1.5–2.9 METs) was negatively associated (β = −.24, p<.01) and hard physical activity (≥9 METs) positively associated (β = .45, p<.001) with cardiorespiratory fitness. Vigorous and hard physical activity were associated with cardiorespiratory fitness for boys (F = 5.64, p<.01) whereas light, moderate and hard physical activity were associated with physical fitness for girls (F = 10.23, p<.001). No association was found between sedentary time and cardiorespiratory fitness (r = −.13, p>.05). Sedentary to active transitions revealed little variability between cardiorespiratory fitness tertiles. Conclusions Hard physical activity (≥9 METs) holds greater potential for cardiorespiratory fitness compared to physical activity of lower intensities. There was no relationship between sedentary behaviour and cardiorespiratory fitness. These findings suggest that, for children, advice should focus on higher intensity physical activity and not sedentary behaviour as a means to maintain or improve cardiorespiratory fitness. Future research should explore longitudinal relationships between hard physical activity, cardiorespiratory fitness and health parameters.

The Hypertriglyceridemic Waist, Waist-to-Height Ratio, and Cardiometabolic Risk

OBJECTIVE To investigate whether the hypertriglyceridemic waist (HW) phenotype and waist-to-height ratio (WHTR) are associated with cardiometabolic disorders in children and adolescents. STUDY DESIGN This was a cross-sectional design study. Anthropometry, biochemical variables, and cardiorespiratory fitness were assessed in 234 participants (122 girls) aged 10-19 years from Bedfordshire, United Kingdom. The HW phenotype was defined as a waist circumference ≥90(th) percentile for age and sex, and triglyceride concentrations ≥1.24 mmol/L, and a high WHTR defined as >0.5. ANCOVA and logistic regression were used in the analysis. RESULT In participants with the HW phenotype, the odds of having high cardiorespiratory fitness (mL/kg/min) were lower (0.045; 95% CI 0.01, 0.42), and the odds of having low high-density lipoprotein cholesterol (4.41; 1.50, 12.91), impaired fasting glucose (3.37; 1.06, 10.72), and ≥1 (4.78; 1.32, 17.29) and ≥2 risk factors (7.16; 2.38, 21.54) were higher than those without the phenotype. Those with a high WHTR had higher odds of having low high-density lipoprotein cholesterol (2.57; 1.11, 5.95), high diastolic blood pressure (3.21; 1.25, 8.25), and ≥2 risk factors (5.57; 2.05, 15.17) than those with normal WHTR. CONCLUSION The HW phenotype may be a better simple marker than WHTR for identifying children and adolescents at risk for cardiometabolic disorders.

Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults

Breaking up periods of prolonged sitting can negate harmful metabolic effects but the influence on appetite and gut hormones is not understood and is investigated in this study. Thirteen sedentary (7 female) participants undertook three 5-h trials in random order: (i) uninterrupted sitting (SIT), (ii) seated with 2-min bouts of light-intensity walking every 20 min (SIT + LA), and (iii) seated with 2-min bouts of moderate-intensity walking every 20 min (SIT + MA). A standardised test drink was provided at the start of each trial and an ad libitum pasta test meal provided at the end of each trial. Subjective appetite ratings and plasma acylated ghrelin, peptide YY, insulin, and glucose were measured at regular intervals. Area under the curve (AUC) was calculated for each variable. AUC values for appetite and gut hormone concentrations were unaffected in the activity breaks conditions compared with uninterrupted sitting (linear mixed modelling: p > 0.05). Glucose AUC was lower in SIT + MA than in SIT + LA (p = 0.004) and SIT (p = 0.055). There was no difference in absolute ad libitum energy intake between conditions (p > 0.05); however, relative energy intake was lower in SIT + LA (39%; p = 0.011) and SIT + MA (120%; p < 0.001) than in SIT. In conclusion, breaking up prolonged sitting does not alter appetite and gut hormone responses to a meal over a 5-h period. Increased energy expenditure from activity breaks could promote an energy deficit that is not compensated for in a subsequent meal.

Choice of Activity-Intensity Classification Thresholds Impacts upon Accelerometer-Assessed Physical Activity-Health Relationships in Children

Background It is unknown whether using different published thresholds (PTs) for classifying physical activity (PA) impacts upon activity-health relationships. This study explored whether relationships between PA (sedentary [SED], light PA [LPA], moderate PA [MPA], moderate-to-vigorous PA, vigorous PA [VPA]) and health markers differed in children when classified using three different PTs. Methods 104 children (63 girls) aged 10–14 years wore an RT3 triaxial accelerometer for seven days and measures of adiposity and cardiometabolic risk markers were taken. Results Significant associations (p< .05) in boys were found between LPA and body mass index z-score and waist circumference z-score for the Rowlands et al PT only (β =  .459 and.401, respectively) and body fat% (BF%) for the Chu et al PT only (β = .322) and in girls with BF% for the Rowlands et al PT only (β =  .303) and systolic BP and blood glucose for the Vanhelst et al PT only (β = −.298 and −.283, respectively). MPA was significantly (p<.05) associated with BF%, diastolic BP, and cardiorespiratory fitness (CRF) for the Chu et al PT only in girls (β = −.436, −.529, and .446, respectively). SED was significantly (p<.05) associated with triglycerides (β = .492) for the Rowlands et al PT only in boys and VPA with CRF (p<.05) for the Rowlands et al and Vanhelst et al PTs only in girls (β = .416 and .352, respectively). Conclusions The choice of PT impacted upon activity-health relationships. A consensus on appropriate accelerometer thresholds for quantifying PA intensity and sedentary behaviour is needed in order to make accurate evidence-based recommendations for health promotion.

The triglyceride to high-density lipoprotein ratio identifies children who may be at risk of developing cardiometabolic disease.

It is important to develop simple, reliable methods to identify high‐risk individuals who may benefit from intervention. This study investigated the association between the triglyceride to high‐density lipoprotein cholesterol (TG/HDL) ratio and cardiometabolic risk, cardiorespiratory fitness and physical activity in children.

The Impact of Active Workstations on Workplace Productivity and Performance: A Systematic Review

Active workstations have been recommended for reducing sedentary behavior in the workplace. It is important to understand if the use of these workstations has an impact on worker productivity. The aim of this systematic review was to examine the effect of active workstations on workplace productivity and performance. A total of 3303 articles were initially identified by a systematic search and seven articles met eligibility criteria for inclusion. A quality appraisal was conducted to assess risk of bias, confounding, internal and external validity, and reporting. Most of the studies reported cognitive performance as opposed to productivity. Five studies assessed cognitive performance during use of an active workstation, usually in a single session. Sit-stand desks had no detrimental effect on performance, however, some studies with treadmill and cycling workstations identified potential decreases in performance. Many of the studies lacked the power required to achieve statistical significance. Three studies assessed workplace productivity after prolonged use of an active workstation for between 12 and 52 weeks. These studies reported no significant effect on productivity. Active workstations do not appear to decrease workplace performance.

Associations between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10–14-year-old children: The HAPPY study

ABSTRACT This study examines the association between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10–14-year-old children. This cross-sectional design study analysed accelerometry-determined sedentary behaviour and physical activity collected over 7 days from 111 (66 girls) UK schoolchildren. Objective outcome measures included waist circumference, fasting lipids, fasting glucose, blood pressure, and cardiorespiratory fitness. Logistic regression was used for the main data analysis. After adjustment for confounders, the odds of having hypertriglyceridaemia (P = 0.03) and an increased clustered cardiometabolic risk score (P = 0.05) were significantly higher in children who engaged in more prolonged sedentary bouts per day. The number of breaks in sedentary time per day was not associated with any cardiometabolic risk factor, but longer mean duration of daily breaks in sedentary time were associated with a lower odds of having abdominal adiposity (P = 0.04) and elevated diastolic blood pressure (P = 0.01). These associations may be mediated by engagement in light activity. This study provides evidence that avoiding periods of prolonged uninterrupted sedentary time may be important for reducing cardiometabolic disease risk in children.

Reducing prolonged sedentary time using a treadmill desk acutely improves cardiometabolic risk markers in male and female adults

ABSTRACT This study evaluated the acute effects of interrupting prolonged sitting with an accumulated 2 h of light-intensity walking on postprandial cardiometabolic risk markers. In this randomised crossover trial, 24 participants (twelve males) aged 18–55 years took part in two, 6.5 h conditions: 1) prolonged sitting (SIT) and 2) sitting interrupted hourly with 20 min light-intensity treadmill desk walking at between 1.2–3.5 km/h−1 (INT-SIT). Standardized meals were provided at 0 h and 3 h. Blood samples and blood pressure measures were taken hourly. Statistical analyses were completed using linear mixed models. Postprandial incremental area under the curve responses (mmol/L∙6.5 h) for glucose (4.52 [3.47, 5.56] and 6.66 [5.62, 7.71] for INT-SIT and SIT, respectively) and triglycerides (1.96 [0.96, 2.96] and 2.71 [1.70, 3.71] for INT-SIT and SIT, respectively) were significantly lower in INT-SIT than SIT. Mean systolic and diastolic blood pressure responses were lower by 3% and 4%, respectively, in INT-SIT than SIT (P < 0.05). There was no significant condition x sex interaction effect for any outcomes (P > 0.05). These findings suggest that interrupting sitting with an accumulated 2 h of light-intensity walking acutely improves cardiometabolic risk levels in males and females compared with prolonged sitting.

Beneficial postprandial lipaemic effects of interrupting sedentary time with high-intensity physical activity versus a continuous moderate-intensity physical activity bout: A randomised crossover trial

OBJECTIVES To compare the postprandial cardiometabolic response to prolonged sitting, continuous moderate-intensity physical activity (PA) followed by prolonged sitting, and interrupting prolonged sitting with hourly high-intensity PA breaks. DESIGN Three-condition randomised crossover trial. METHODS Fourteen sedentary and inactive adults aged 29±9years took part in three, 8-h conditions: (1) prolonged sitting (SIT), (2) a continuous 30-min moderate-intensity PA bout followed by prolonged sitting (CONT-SIT), and (3) sitting interrupted hourly with 2min 32s high-intensity PA bouts (SIT-ACT). The treadmill PA in conditions 2 and 3 were matched for energy expenditure. Two standardised test meals were consumed during each condition. Incremental area under the curve (iAUC) for each 8-h condition was calculated for glucose, insulin, triglyceride, and high-density lipoprotein cholesterol (HDL-C) concentrations. Statistical analyses were completed using linear mixed models. RESULTS Compared with SIT, SIT-ACT lowered triglyceride iAUC by 2.23mmol/L∙8h (95% CI -4.33, -0.13) and raised HDL-C iAUC by 0.99mmol/L∙8h (0.05, 1.93) (all p≤0.038). There was no significant difference in triglyceride or HDL-C iAUC between CONT-SIT and SIT or SIT-ACT (p≥0.211). There were no significant differences between conditions for glucose or insulin iAUC (p≥0.504). CONCLUSIONS This study suggests that interrupting prolonged sitting with hourly high-intensity PA breaks acutely improves postprandial triglyceride and HDL-C concentrations compared with prolonged sitting, whereas a continuous moderate-intensity PA bout does not.