Sedentary Behavior Research Priorities--NHLBI/NIA Sedentary Behavior Workshop Summary

The persistence of stress-induced physical inactivity in rats: an investigation of central monoamine neurotransmitters and skeletal muscle oxidative stress

Introduction

Sedentary lifestyles have reached epidemic proportions world-wide. A growing body of literature suggests that exposures to adverse experiences (e.g., psychological traumas) are a significant risk factor for the development of physically inactive lifestyles. However, the biological mechanisms linking prior stress exposure and persistent deficits in physical activity engagement remains poorly understood.

Methods

The purpose of this study was twofold. First, to identify acute stress intensity thresholds that elicit long-term wheel running deficits in rats. To that end, young adult male rats were exposed to a single episode of 0, 50, or 100 uncontrollable tail shocks and then given free access to running wheels for 9 weeks. Second, to identify stress-induced changes to central monoamine neurotransmitters and peripheral muscle physiology that may be maladaptive to exercise output. For this study, rats were either exposed to a single episode of uncontrollable tail shocks (stress) or left undisturbed in home cages (unstressed). Eight days later, monoamine-related neurochemicals were quantified by ultra-high performance liquid chromatography (UHPLC) across brain reward, motor, and emotion structures immediately following a bout of graded treadmill exercise controlled for duration and intensity. Additionally, protein markers of oxidative stress, inflammation, and metabolic activity were assessed in the gastrocnemius muscle by Western blot.

Results

For experiment 1, stress exposure caused a shock number-dependent two to fourfold decrease in wheel running distance across the entire duration of the study. For experiment 2, stress exposure curbed an exercise-induced increase of dopamine (DA) turnover measures in the prefrontal cortex and hippocampus, and augmented serotonin (5HT) turnover in the hypothalamus and remaining cortical area. However, stress exposure also caused several monoaminergic changes independent of exercise that could underlie impaired motivation for physical activity, including a mild dopamine deficiency in the striatal area. Finally, stress potently increased HSP70 and lowered SOD2 protein concentrations in the gastrocnemius muscle, which may indicate prolonged oxidative stress.

Discussion

These data support some of the possible central and peripheral mechanisms by which exposure to adverse experiences may chronically impair physical activity engagement.

Latent Class Analysis of Lifestyle Risk Factors and Association with Overweight and/or Obesity in Children and Adolescents: Systematic Review

Background: Multiple modifiable lifestyle factors are well-known contributors to many health problems. Objectives: This study aims to determine the association between latent class analysis (LCA) of modifiable lifestyle risk factors with being overweight and/or obese for children and/or adolescents. Methods: Articles were selected from six databases, without limitation regarding language or date. The review included studies that identify latent classes of modifiable lifestyle risk factors [e.g., physical activity (PA), diet, sedentary behavior (SB), and/or unhealthy behavior] by LCA to determine the association between latent classes with being overweight and/or obese. The methodology of the selected studies was evaluated using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Owing to the heterogeneity between latent classes of modifiable lifestyle risk factors with obesity and/or being overweight, the results are described narratively. Results: Using a selection process in two phases, nine articles were included. All of the included studies were of high methodological quality. The studies were conducted in six different countries: the USA, Brazil, Canada, Portugal, Italy, and Australia. Sample sizes ranged from 166 to 18.587 children and adolescents, and in terms of age (range 5-19 years). Across study clusters characterized by low consumption of fruit and vegetables, and high consumption of fatty foods, sugar snack foods, sweets, chips and fries, low PA (<1 hour each day), and high SB (screen time and TV >2 hours/day), sleep time (<10 hours/day) were positively associated with being overweight and/or obese. Conclusion: Overall there is good evidence to support that the modifiable lifestyle risk factors clustered together by LCA should be novel targets for the treatment of obesity and its associated comorbidities.

Participants' Perceptions on the Use of Wearable Devices to Reduce Sitting Time: Qualitative Analysis

Background

Recent epidemiological evidence indicates that, on average, people are sedentary for approximately 7.7 hours per day. There are deleterious effects of prolonged sedentary behavior that are separate from participation in physical activity and include increased risk of weight gain, cancer, metabolic syndrome, diabetes, and heart disease. Previous trials have used wearable devices to increase physical activity in studies; however, additional research is needed to fully understand how this technology can be used to reduce sitting time.

Objective

The purpose of this study was to explore the potential of wearable devices as an intervention tool in a larger sedentary behavior study through a general inductive and deductive analysis of focus group discussions.

Methods

We conducted four focus groups with 15 participants to discuss 7 different wearable devices with sedentary behavior capabilities. Participants recruited for the focus groups had previously participated in a pilot intervention targeting sedentary behavior over a 3-week period and were knowledgeable about the challenges of reducing sitting time. During the focus groups, participants commented on the wearability, functionality, and feedback mechanism of each device and then identified their two favorite and two least favorite devices. Finally, participants designed and described their ideal or dream wearable device. Two researchers, who have expertise analyzing qualitative data, coded and analyzed the data from the focus groups. A thematic analysis approach using Dedoose software (SocioCultural Research Consultants, LLC version 7.5.9) guided the organization of themes that reflected participants’ perspectives.

Results

Analysis resulted in 14 codes that we grouped into themes. Three themes emerged from our data: (1) features of the device, (2) data the device collected, and (3) how data are displayed.

Conclusions

Current wearable devices for increasing physical activity are insufficient to intervene on sitting time. This was especially evident when participants voted, as several participants reported using a “process of elimination” as opposed to choosing favorites because none of the devices were ideal for reducing sitting time. To overcome the limitations in current devices, future wearable devices designed to reduce sitting time should include the following features: waterproof, long battery life, accuracy in measuring sitting time, real time feedback on progress toward sitting reduction goals, and flexible options for prompts to take breaks from sitting.

Physical Inactivity, Sedentary Behavior and Chronic Diseases

New research into physical activity suggests that it is no longer sufficient just to meet minimum levels recommended by health guidelines in order to reduce cardiovascular risk. Both physical inactivity and sedentary behavior have their own health hazards and need to be addressed separately, in order to explore their different deleterious mechanisms. The aim of this review was to define and to characterize both concepts, and their relationship with major non-communicable chronic diseases. A PubMed database search was undertaken, using the following key words: physical activity, physical inactivity, sedentarism, sedentary behavior, and non-communicable chronic disease. This literature review provides an updated view on physical inactivity and sedentary behavior, and reevaluates their prevalence and association with major non-communicable chronic disease.

Physical Activity and Changes in Adiposity in the Transition from Elementary to Middle School

OBJECTIVES

This study examined the longitudinal associations of objectively measured physical activity, sedentary behavior, and diet quality with two measures of adiposity and a measure of weight status.

METHODS

A total of 658 children from 21 elementary schools (45.1% boys; 40% white, 33% black, 9% Hispanic, and 18% other race/ethnicity) were assessed at least twice in fifth, sixth, and/or seventh grade. Fat mass index (FMI), percent body fat (PBF), and BMI were calculated from body weight, standing and seated heights, and bioelectrical impedance (BIA) measured each year.

RESULTS

At follow-up, both FMI and PBF decreased among boys and increased among girls, while BMI increased in both boys and girls. After controlling for race/ethnicity, parent education, and maturity offset at baseline, growth curve analyses showed that moderate-to-vigorous physical activity (MVPA) was significantly and negatively associated with FMI, PBF, and BMI for both boys and girls. After forming tertiles of fifth grade MVPA, least-square means for FMI, PBF, and BMI were examined by grade and gender. For both boys and girls, higher MVPA was associated with lower FMI, PBF, and BMI at all three grade levels. The relationships between sedentary behavior and diet quality and FMI, PBF, and BMI were not consistent for boys or girls.

CONCLUSIONS

As boys and girls transitioned from elementary to middle school, children who participated in higher levels of MVPA maintained more favorable levels of two indicators of adiposity and a measure of weight status. These findings support the need for interventions to help children meet current public health guidelines for physical activity.

Sedentary Behavior and Cardiovascular Risk in Older Adults: a Scoping Review

Sedentary behavior is an emerging risk factor for cardiovascular disease (CVD) and may be particularly relevant to the cardiovascular health of older adults. This scoping review describes the existing literature examining the prevalence of sedentary time in older adults with CVD and the association of sedentary behavior with cardiovascular risk in older adults. We found that older adults with CVD spend >75 % of their waking day sedentary, and that sedentary time is higher among older adults with CVD than among older adults without CVD. High sedentary behavior is consistently associated with worse cardiac lipid profiles and increased cardiac risk scores in older adults; the associations of sedentary behavior with blood pressure, CVD incidence, and CVD-related mortality among older adults are less clear. Future research with larger sample sizes using validated methods to measure sedentary behavior are needed to clarify the association between sedentary behavior and cardiovascular outcomes in older adults.

Socio-demographic, behavioural and cognitive correlates of work-related sitting time in German men and women

BACKGROUND

Sitting time is ubiquitous for most adults in developed countries and is most prevalent in three domains: in the workplace, during transport and during leisure time. The correlates of prolonged sitting time in workplace settings are not well understood. Therefore, the aim of this study was to examine the gender-specific associations between the socio-demographic, behavioural and cognitive correlates of work-related sitting time.

METHODS

A cross-sectional sample of working German adults (n = 1515; 747 men; 43.5 ± 11.0 years) completed questionnaires regarding domain-specific sitting times and physical activity (PA) and answered statements concerning beliefs about sitting. To identify gender-specific correlates of work-related sitting time, we used a series of linear regressions.

RESULTS

The overall median was 2 hours of work-related sitting time/day. Regression analyses showed for men (β = -.43) and for women (β = -.32) that work-related PA was negatively associated with work-related sitting time, but leisure-related PA was not a significant correlate. For women only, transport-related PA (β = -.07) was a negative correlate of work-related sitting time, suggesting increased sitting times during work with decreased PA in transport. Education and income levels were positively associated, and in women only, age (β = -.14) had a negative correlation with work-related sitting time. For both genders, TV-related sitting time was negatively associated with work-related sitting time. The only association with cognitive correlates was found in men for the belief 'Sitting for long periods does not matter to me' (β = .10) expressing a more positive attitude towards sitting with increasing sitting durations.

CONCLUSIONS

The present findings show that in particular, higher educated men and women as well as young women are high-risk groups to target for reducing prolonged work-related sitting time. In addition, our findings propose considering increasing transport-related PA, especially in women, as well as promoting recreation-related PA in conjunction with efforts to reduce long work-related sitting times.