Effect of sedentary behavior interventions on vascular function in adults: A systematic review and meta-analysis

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.

What is the current state of research concerning self-efficacy in exercise behaviour? Protocol for two systematic evidence maps

INTRODUCTION

Knowing about a risk factor is not sufficient to ensure corresponding behaviour as additional psychological factors play a role. Self-efficacy is one of the major factors. This also applies to physical activity and exercise behaviour, which is a major public health topic in both primary and secondary prevention. The amount of research on self-efficacy in exercise behaviour is high yet remains uncharted. This protocol presents the research design for two systematic evidence maps on self-efficacy in exercise behaviour in (1) primary prevention and (2) secondary prevention. These maps will thus provide a comprehensive overview over the current state in published empirical research as a starting point for future researchers.

METHODS AND ANALYSIS

The databases Medline (via PubMed) and PsycINFO (via EbscoHost) will be searched using the search terms 'self-efficacy' and any of the search terms 'sport' and 'exercise' in titles and abstracts. All empirical research studies which have measured self-efficacy in relation to exercise behaviour will be included. The primary prevention systematic evidence map will aggregate all studies on healthy humans and the secondary prevention systematic evidence map will include all studies on humans with a pre-existing condition. We will extract and present the data points authors, title, year, sample size (N), age groups, surveyed sport and method of measuring self-efficacy in both systematic evidence maps. Moreover, we will extract and present the target group in the systematic evidence map on primary prevention and the pre-existing condition in the systematic evidence map on secondary prevention. In addition to a data table, we will create freely accessible evidence maps in the form of graphs.

ETHICS AND DISSEMINATION

Since this is a protocol, an ethics approval is not required for the presented and planned work. The results of the two systematic evidence maps will be disseminated via publication in international peer-reviewed journals. In addition, data will be shared in detail via the Open Science Framework platform.

Arterial stiffness and the reallocation of time between device-measured 24-hour movement behaviours: A compositional data analysis

BACKGROUND AND AIMS

Arterial stiffness predicts cardiovascular morbidity and mortality. We aimed to quantify the differences in arterial stiffness associated with reallocating time between 24-h movement behaviours.

METHODS

This observational cross-sectional study included Luxembourg residents aged 25-79y who each provided ≥4 valid days of triaxial accelerometry (n = 1001). Covariable adjusted compositional isotemporal substitution models were used to examine if theoretical reallocations of time between device-measured sedentariness, the sleep period, light physical activity (PA), and moderate-to-vigorous PA (MVPA) were associated with the percentage difference in carotid-femoral pulse wave velocity (cfPWV). We further investigated if replacing sedentary time accumulated in prolonged (≥30 min) with non-prolonged (<30 min) bouts was associated with arterial stiffness. The results are presented as 30 min time exchanges (β (95% confidence interval)).

RESULTS

Beneficial associations with lower cfPWV were observed when reallocating time to MVPA from the sleep period (-1.38 (-2.63 to -0.12) %), sedentary time (-1.70 (-2.76 to -0.62) %), and light PA (-2.51 (-4.55 to -0.43) %), respectively. Larger associations in the opposite direction were observed when reallocating MVPA to the same behaviours (for example, replacing MVPA with sedentary time: 2.50 (0.85-4.18) %). Replacing prolonged with non-prolonged sedentary time was not associated with cfPWV (-0.27 (-0.86 to 0.32) %). In short sleepers, reallocating sedentary time to the sleep period was favourable (-1.96 (-3.74 to -0.15) %).

CONCLUSIONS

Increasing or at least maintaining MVPA appears to be important for arterial health in adults. Extending sleep in habitually short sleepers, specifically by redistributing sedentary time, may also be important.

Association of lifestyle habits and cardiovascular risk among sedentary adults

This study aimed to analyze the association of lifestyle habits (physical activity, sleep habits, and eating habits) with cardiovascular risk (arterial stiffness and autonomic nervous system function) among sedentary adults. Sixty adults of sedentariness and physical activity were evaluated by accelerometers; sleep and eating habits were assessed by questionnaires; cardiovascular risks were assessed by pulse wave velocity (PWV), ankle-brachial index, flow mediated dilation, and heart rate variability; circulating biomarkers were also determined. Prolonged sitting (represented by longer maximum length of sedentary bouts, lower length of sedentary breaks, and more total time of sitting) were (P < .05) significantly associated with matrix metalloproteinases, neuropeptide Y, C-reactive protein, peptide Y, ghrelin, and leptin; significant associations (P < .05) were also observed of total time in physical activity with most circulating biomarkers except interleukin-6, tumor necrosis factor-α, and adiponectin. Sleep habits, especially sleep efficiency, were (P < .05) significantly associated with PWV, ankle-brachial index, and circulating biomarkers. Eating habits (including emotional overeating and enjoyment of food) were (P < .05) significantly associated with PWVs and flow mediated dilation; satiety responsiveness and enjoyment of food were (P < .05) significantly associated with low-frequency spectral component expressed in normalized units, high frequency spectral component expressed in normalized units, and ratio between low-frequency/high frequency spectral component expressed in normalized units. The findings indicated that several lifestyle habits among sedentary adults were closely associated with increased cardiovascular risk. Sedentary people were encouraged to live with sufficient physical activity, good sleep, and healthy eating habits for decreasing arterial stiffness and balancing autonomic nervous function.

Effect of Exercise on Carotid Artery Intima-Media Thickness in Adults: A Systematic Review and Meta-Analysis

BACKGROUND

Carotid intima-media thickness (cIMT) is a validated surrogate marker of atherosclerosis that is independently associated with the risk for cardiovascular disease. Recent studies on the effect of exercise on cIMT have yielded conflicting results.

METHODS

Studies that were available up until October 30, 2021 from the PubMed, Cochrane Library, Embase, and Web of Science databases were included in the analysis. Subgroup analyses were performed to determine the effects of the type, intensity, and duration of exercise on cIMT.

RESULTS

This review included 26 studies with 1370 participants. Compared with control participants, those who engaged in exercise showed a decline in cIMT (weighted mean difference [WMD] -0.02; 95% confidence interval [CI], -0.03 to -0.01; I2 = 90.1%). Participants who engaged in aerobic (WMD -0.02; 95% CI, -0.04 to -0.01; I2 = 52.7%) or resistance (WMD -0.01; 95% CI, -0.02 to -0.00; I2 = 38.5%) exercise showed lower cIMT compared with control participants. An exercise duration of >6 months was associated with a 0.02 mm reduction in cIMT. In participants with low cIMT at baseline (<0.7 mm), exercise alone was not associated with a change in cIMT (WMD -0.01; 95% CI, -0.03 to 0.00; I2 = 93.9%).

CONCLUSIONS

Exercise was associated with reduced cIMT in adults. Aerobic exercise is associated with a greater decline in cIMT than other forms of exercise. Large, multicenter, randomized controlled trials are required to establish optimal exercise protocols for improving the pathological process of atherosclerosis.

Is Sedentary Behavior a Novel Risk Factor for Cardiovascular Disease?

PURPOSE OF REVIEW

Review the most recent evidence on the role of sedentary behavior in the prevention of cardiovascular disease (CVD).

RECENT FINDINGS

Prospective cohort studies continue to suggest a relationship between sedentary behavior and CVD, but the dose-response association, and the implications of sedentary pattern (vs. total volume) and context on CVD risk require further investigation. Most recent evidence suggests that physical activity influences the association between sedentary time and CVD risk, and that replacing sedentary time with other movement behaviors yields cardiometabolic benefits. Short-term intervention studies have further demonstrated that interrupting prolonged sitting with bouts of physical activity can elicit acute improvements on cardiometabolic biomarkers and vascular function relative to prolonged, uninterrupted sitting, albeit limited evidence exists on the long-term effects. More conclusive evidence regarding the implications of sedentary time on CVD risk is warranted before the optimal sedentary behavior reduction prescription for the prevention of CVD can be elucidated.

The Acute Effects of Prolonged Uninterrupted Sitting on Vascular Function: A Systematic Review and Meta-analysis

OBJECTIVE

This study aimed to determine the dose-response relationship between prolonged sitting and vascular function in healthy individuals and those with metabolic disturbances and to investigate the acute effects, on vascular function, of interventions that target interrupting prolonged sitting.

DESIGN

This is a systematic review with meta-analysis.

DATA SOURCES

Ovid Embase, Ovid Medline, PubMed, and CINAHL were searched from inception to 4 December 2020.

ELIGIBILITY CRITERIA

Randomized crossover trials, quasi-randomized trials, and parallel group trials where vascular function (flow-mediated dilation [FMD]) was assessed before and after an acute period of sedentary behavior was used in this study.

RESULTS

Prolonged sitting resulted in a significant decrease in the standardized mean change (SMC) for lower-limb FMD at the 120-min (SMC = -0.85, 95% confidence interval [CI] = -1.32 to -0.38) and 180-min (SMC = -1.18, 95% CI = -1.69 to -0.66) time points. A similar pattern was observed for lower-limb shear rate. No significant changes were observed for any outcomes in the upper limb. Subgroup analysis indicated that prolonged sitting decreased lower-limb FMD in healthy adults (SMC = -1.33, 95% CI = -1.89 to -0.78) who had higher a priori vascular endothelial function, but not in those with metabolic and vascular dysfunction (SMC = -0.51, 95% CI = -1.18 to 0.15). Interrupting sitting with active interruptions increased the standardized mean difference for FMD, relative to prolonged sitting, but it was not statistically significant (0.13, 95% CI = -0.20 to 0.45).

CONCLUSIONS

Lower-limb vascular function is progressively impaired as a consequence of prolonged sitting, up to 180 min. A similar trend was not observed in upper-limb vascular function. Subgroup analysis indicated that prolonged sitting negatively affects healthy populations, a finding not observed in those with metabolic disturbances. Regularly interrupting sitting with activity may be beneficial for those with metabolic disturbances.

Prediction of stroke using an algorithm to estimate arterial stiffness

Background

Arterial stiffness is important because it is associated with adverse cardiovascular events including stroke. Methods that are based on pulse wave velocity have significant limitations in estimating arterial stiffness. The purpose of this paper is to present a novel easy to apply non-invasive method to estimate arterial stiffness that is based on pulse pressure.

Methods

Two indices to estimate arterial stiffness, (1) arterial stiffness 1 (AS1) and (2) arterial stiffness 2 (AS2) were developed and applied in two National Institutes of Health funded clinical trials, the Systolic Hypertension in the Elderly Program and the Systolic Blood Pressure Intervention Trial. These indices were developed by fitting individual survival models for selected predictor variables to the response, i.e. time to stroke, by selecting the coefficients that were statistically significant at the 0.05 α level after adjusting the variable weights. The indices were derived as the weighted linear combination of the coefficients.

Results

AS1 and AS2 performed well in two goodness of fit criteria i.e. overall model p-value and concordance correlation. Comparison of Cox models using indices AS1 and AS2 and chronological age indicated that AS1 and AS2 independently predicted the occurrence of stroke at five years better than chronological age. Nearly identical effects were observed when the analyses were limited to Black participants in SPRINT with a concordance correlation of 0.80 and log rank test p-value of 0.007.

Conclusion

These indices that are derived from pulse pressure predict the occurrence of stroke better than either pulse pressure or chronological age alone and may be used in designing new randomized clinical trials, and possibly incorporated in hypertension and stroke guidelines.