The Effect of Replacing Sitting With Standing on Cardiovascular Risk Factors: A Systematic Review and Meta-analysis

Effect of Active Workstations on Neurocognitive Performance and Typing Skills: A Randomized Clinical Trial

BACKGROUND

Extended sedentary behavior is a risk factor for chronic disease and mortality, even among those who exercise regularly. Given the time constraints of incorporating physical activity into daily schedules, and the high likelihood of sitting during office work, this environment may serve as a potentially feasible setting for interventions to reduce sedentary behavior.

METHODS AND RESULTS

A randomized cross-over clinical trial was conducted at an employee wellness center. Four office settings were evaluated on 4 consecutive days: stationary or sitting station on day 1 (referent), and 3 subsequent active workstations (standing, walking, or stepper) in randomized order. Neurocognitive function (Selective Attention, Grammatical Reasoning, Odd One Out, Object Reasoning, Visuospatial Intelligence, Limited-Hold Memory, Paired Associates Learning, and Digit Span) and fine motor skills (typing speed and accuracy) were tested using validated tools. Average scores were compared among stations using linear regression with generalized estimating equations to adjust standard errors. Bonferroni method adjusted for multiple comparisons. Healthy subjects were enrolled (n=44), 28 (64%) women, mean±SD age 35±11 years, weight 75.5±17.1 kg, height 168.5±10.0 cm, and body mass index 26.5±5.2 kg/m2. When comparing active stations to sitting, neurocognitive test either improved or remained unchanged, while typing speed decreased without affecting typing errors. Overall results improved after day 1, suggesting habituation. We observed no major differences across active stations, except decrease in average typing speed 42.5 versus 39.7 words per minute with standing versus stepping (P=0.003).

CONCLUSIONS

Active workstations improved cognitive performance, suggesting that these workstations can help decrease sedentary time without work performance impairment.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT06240286.

Physiology of sedentary behavior

Sedentary behaviors (SB) are characterized by low energy expenditure while in a sitting or reclining posture. Evidence relevant to understanding the physiology of SB can be derived from studies employing several experimental models: bed rest, immobilization, reduced step count, and reducing/interrupting prolonged SB. We examine the relevant physiological evidence relating to body weight and energy balance, intermediary metabolism, cardiovascular and respiratory systems, the musculoskeletal system, the central nervous system, and immunity and inflammatory responses. Excessive and prolonged SB can lead to insulin resistance, vascular dysfunction, shift in substrate use toward carbohydrate oxidation, shift in muscle fiber from oxidative to glycolytic type, reduced cardiorespiratory fitness, loss of muscle mass and strength and bone mass, and increased total body fat mass and visceral fat depot, blood lipid concentrations, and inflammation. Despite marked differences across individual studies, longer term interventions aimed at reducing/interrupting SB have resulted in small, albeit marginally clinically meaningful, benefits on body weight, waist circumference, percent body fat, fasting glucose, insulin, HbA1c and HDL concentrations, systolic blood pressure, and vascular function in adults and older adults. There is more limited evidence for other health-related outcomes and physiological systems and for children and adolescents. Future research should focus on the investigation of molecular and cellular mechanisms underpinning adaptations to increasing and reducing/interrupting SB and the necessary changes in SB and physical activity to impact physiological systems and overall health in diverse population groups.

Do Sit-Stand Tables Affect Physical Behavior and Body Composition Similarly in Normal-Weight and Overweight Office Workers? A Pilot Study

OCCUPATIONAL APPLICATIONSSedentary behavior is a significant health concern among office workers. We completed the same 6-month sit-stand table intervention at work for groups of normal-weight and overweight workers, and compared it to not having sit-stand tables. The intervention caused the intended decrease in sitting time in both groups and a corresponding increase in standing. We did not find compensation effects on physical behavior outside of work. Furthermore, the intervention did not change the composition of fat, lean, and bone mass in either group. Thus, strategies including initiatives to increase physical activity are likely needed to have effects on body composition; and an intervention needs to be sustained for longer than six months for any changes in body composition to be observed.

Using machine learning to predict cardiovascular risk using self-reported questionnaires: Findings from the 45 and up study

BACKGROUND

Machine learning has been shown to outperform traditional statistical methods for risk prediction model development. We aimed to develop machine learning-based risk prediction models for cardiovascular mortality and hospitalisation for ischemic heart disease (IHD) using self-reported questionnaire data.

METHODS

The 45 and Up Study was a retrospective population-based study in New South Wales, Australia (2005-2009). Self-reported healthcare survey data on 187,268 participants without a history of cardiovascular disease was linked to hospitalisation and mortality data. We compared different machine learning algorithms, including traditional classification methods (support vector machine (SVM), neural network, random forest and logistic regression) and survival methods (fast survival SVM, Cox regression and random survival forest).

RESULTS

A total of 3687 participants experienced cardiovascular mortality and 12,841 participants had IHD-related hospitalisation over a median follow-up of 10.4 years and 11.6 years respectively. The best model for cardiovascular mortality was a Cox survival regression with L1 penalty at a re-sampled case/non-case ratio of 0.3 achieved by under-sampling of the non-cases. This model had the Uno's and Harrel's concordance indexes of 0.898 and 0.900 respectively. The best model for IHD hospitalisation was a Cox survival regression with L1 penalty at a re-sampled case/non-case ratio of 1.0 with Uno's and Harrel's concordance indexes of 0.711 and 0.718 respectively.

CONCLUSION

Machine learning-based risk prediction models developed using self-reported questionnaire data had good prediction performance. These models may have the potential to be used in initial screening tests to identify high-risk individuals before undergoing costly investigation.

Reducing Sedentary Time and Whole-Body Insulin Sensitivity in Metabolic Syndrome: A 6-Month Randomized Controlled Trial

PURPOSE

This study aimed to investigate whether a reduction in daily sedentary behavior (SB) improves insulin sensitivity in adults with metabolic syndrome in 6 months, without adding intentional exercise training.

METHODS

Sixty-four sedentary inactive middle-age adults with overweight and metabolic syndrome (mean (SD) age, 58 (7) yr; mean (SD) body mass index, 31.6 (4.3) kg·m -2 ; 27 men) were randomized into intervention and control groups. The 6-month individualized behavioral intervention supported by an interactive accelerometer and a mobile application aimed at reducing daily SB by 1 h compared with baseline. Insulin sensitivity by hyperinsulinemic euglycemic clamp, body composition by air displacement plethysmography, and fasting blood samples were analyzed before and after the intervention. SB and physical activity were measured with hip-worn accelerometers throughout the intervention.

RESULTS

SB decreased by 40 (95% confidence interval, 17-65) min·d -1 , and moderate-to-vigorous physical activity increased by 20 (95% confidence interval, 11-28) min·d -1 on average in the intervention group with no significant changes in these outcomes in the control group. After 6 months, fasting plasma insulin decreased (~1 mU·L -1 ) in the intervention group compared with the control group (time-group, P = 0.0081), but insulin sensitivity did not change in either group. The changes in body mass or adiposity did not differ between groups. Among all participants, the changes in SB and body mass correlated inversely with the change in insulin sensitivity ( r = -0.31, -0.44; P = 0.025, 0.0005, respectively).

CONCLUSIONS

An intervention aimed at reducing daily SB resulted in slightly decreased fasting insulin, but had no effects on insulin sensitivity or body adiposity. However, as the change in insulin sensitivity associated with the changes in SB and body mass, multifaceted interventions targeting to weight loss are likely to be beneficial in improving whole-body insulin sensitivity.

The role of physical activity in the regulation of body weight: The overlooked contribution of light physical activity and sedentary behaviors

The role of physical activity (PA) in the regulation of body weight is still a major topic of debate. This may be because studies have essentially focused on the effects of moderate/vigorous PA (MVPA) on body weight while overlooking the other components of PA, namely, light-intensity PA (LPA, daily life activities) and sedentary behaviors (SB, too much sitting). In this review, we will (i) describe the history of changes in PA behaviors that occurred with modernization; (ii) review data from cross-sectional and longitudinal studies that examined the associations between PA, SB, and measures of obesity; (iii) review interventional studies that investigated the effects of changes in PA and SB on body weight and adiposity; and (iv) discuss experimental studies that addressed potential biological mechanisms underlying the effects of PA and SB on weight regulation. Overall recent findings support the importance of considering all components of PA to better understand the regulation of energy balance and suggest an important role for LPA and SB in addition to MVPA on body weight regulation. Longitudinal large-scale rigorous studies are needed to advance our knowledge of the role of PA/SB in combating the obesity epidemic.

Are the different cut-off points for sitting time associated with excess weight in adults? A population based study in Latin America

BACKGROUND

Excess weight is increasing worldwide, and in Latin America more than half of the population is excess weight. One of the reasons for this increase has been excessive sitting time. Still, it remains to be seen whether there is an excessive amount of that time in Latin American adults. This study aimed to associate different sitting time cut-off points with the excess weight.

METHODS

Data from the Latin American Study of Nutrition and Health (ELANS), a cross-sectional population-based survey conducted in eight Latin American countries, were used. The excess weight indicators used were body mass index, and waist and neck circumferences. Sitting time was obtained using questionnaires and categorized at different cut-off points. Differences between sitting time categories (< 4 or ≥ 4; < 6 or ≥ 6; and < 8 or ≥ 8 hours/day) and excess weight were obtained by Student's t test for independent samples and the association between sitting time categories and different indicators of excess weight were obtained by logistic regression.

RESULTS

The median of the sitting time was 420 min/day (IQR: 240-600). There were no significant differences between body mass index (kg/m²) and waist circumference (cm) with categories of sitting time. The mean values of neck circumference (cm) were significantly higher in ≥4, ≥6 and ≥ 8 hours/day than < 4, < 6, and < 8 hours/day of sitting time in the pooled sample. Some distinct differences by country were observed. There were significant differences among excess weight by body mass index (63.2% versus 60.8) with < 8 vs ≥8 hours/day of sitting time. The proportion of excess weight by neck circumference was higher in participants who reported ≥4, ≥6, and ≥ 8 hours/day compared to < 4, < 6, and < 8 hours/day of sitting time. Considering ≥8 hours/day of sitting time, higher odds of excess weight were found evaluated by body mass index (OR: 1.10; 95% CI: 1.01, 1.20) and neck circumference (OR: 1.13; CI 95%: 1.03, 1.24) overall.

CONCLUSIONS

Sitting time above 8 hours/day was associated with higher odds of excess weight, even though there were no differences in waist circumference between sitting time categories.

TRIAL REGISTRATION

Clinical Trials NCT02226627. (27/08/2014).

Habitual sedentary time and stationary time are inversely related to aerobic fitness

A one metabolic-equivalent-of-task increase in peak aerobic fitness (peak MET) is associated with a clinically relevant improvement in survival risk and all-cause mortality. The co-dependent impact of free-living physical behaviours on aerobic fitness are poorly understood. The purpose of this study was to investigate the impact of theoretically re-allocating time spent in physical behaviours on aerobic fitness. We hypothesized that substituting sedentary time with any physical activity (at any intensity) would be associated with a predicted improvement in aerobic fitness. Peak volume rate of oxygen uptake ( V ˙ O₂peak) was assessed via indirect calorimetry during a progressive, maximal cycle ergometer protocol in 103 adults (52 females; [38 ± 21] years; [25.0 ± 3.8] kg/m²; V ˙ O₂peak: [35.4 ± 11.5] ml·kg^-1·min^-1). Habitual sedentary time, standing time, light- (LPA), moderate- (MPA), and vigorous-physical activity (VPA) were assessed 24-h/day via thigh-worn inclinometry for up to one week (average: [6.3 ± 0.9] days). Isotemporal substitution modelling examined the impact of replacing one physical behaviour with another. Sedentary time (β = -0.8, 95% CI: [-1.3, -0.2]) and standing time (β = -0.9, 95%CI: [-1.6, -0.2]) were negatively associated with V ˙ O₂peak, whereas VPA was positively associated with relative V ˙ O₂peak (β = 9.2, 95%CI: [0.9, 17.6]). Substituting 30-min/day of VPA with any other behaviour was associated with a 2.4-3.4 higher peak MET. Higher standing time was associated with a lower aerobic fitness. As little as 10-min/day of VPA predicted a clinically relevant 0.8-1.1 peak MET increase. Theoretically, replacing any time with relatively small amounts of VPA is associated with improvements in aerobic fitness.

Standing is associated with insulin sensitivity in adults with metabolic syndrome

OBJECTIVES

To determine how components of accelerometer-measured sedentary behavior (SB) and physical activity (PA), and fitness are associated with insulin sensitivity in adults with metabolic syndrome.

DESIGN

Cross-sectional.

METHODS

Target population was middle-aged (40-65 years) sedentary adults with metabolic syndrome. SB, breaks in SB, standing, and PA were measured for four weeks with hip-worn accelerometers. VO₂max (ml/min/kg) was measured with maximal cycle ergometry. Insulin sensitivity was determined by hyperinsulinaemic-euglycaemic clamp (M-value) and fasting blood sampling (HOMA-IR, insulin). Multivariable regression was used for analyses.

RESULTS

Sixty-four participants (37 women; 58.3 [SD 6.8] years) were included. Participants spent 10.0 (1.0) h sedentary, 1.8 (0.6) h standing, and 2.7 (0.6) h in PA and took 5149 (1825) steps and 29 (8) breaks daily. In sex-, age- and accelerometer wear time-adjusted model SB, standing, steps and VO₂max were associated with M-value (β = -0.384; β = 0.400; β = 0.350; β = 0.609, respectively), HOMA-IR (β = 0.420; β = -0.548; β = -0.252; β = -0.449), and insulin (β = 0.433; β = -0.541; β = -0.252; β = -0.453); all p-values < 0.05. Breaks associated only with M-value (β = 0.277). When further adjusted for body fat %, only standing remained significantly associated with HOMA-IR (β = -0.381) and insulin (β = -0.366); significance was maintained even when further adjusted for SB, PA and fitness. Light and moderate-to-vigorous PA were not associated with insulin sensitivity.

CONCLUSIONS

Standing is associated with insulin sensitivity markers. The association with HOMA-IR and insulin is independent of adiposity, PA, SB and fitness. Further studies are warranted, but these findings encourage replacing sitting with standing for potential improvements in insulin sensitivity in adults at increased type 2 diabetes risk.

Evidence supporting moving more and sitting less

High levels of sedentary time and physical inactivity independently contribute to the development of noncommunicable diseases and premature mortality. Engaging in at least 150 min of moderate or 75 min of vigorous physical activity (PA) is globally recognized as conferring substantial health benefits. However, setting these distinct thresholds and promoting them may have inadvertently created perceptions among the general public that an all or nothing phenomenon exists. Yet, the PA guidelines and a growing body of evidence highlights the robust health benefits associated with becoming more active from a previously sedentary lifestyle, even if the volume of PA performed is below current ideal recommendations. Practitioners providing PA recommendations are encouraged to initially highlight the benefits of moving more and sitting less rather than initially setting lofty, perhaps unachievable, PA goals for inactive individuals. Taking this approach may increase the likelihood of adopting a more physically active lifestyle and ultimately progressing to meet the PA guidelines.