Computing Components of Everyday Stress Responses: Exploring Conceptual Challenges and New Opportunities.

Repeated assessments in everyday life enables collecting ecologically valid data on dynamic, within-persons processes. These methods have widespread utility and application and have been extensively used for the study of stressors and stress responses. Enhanced conceptual sophistication of characterizing intraindividual stress responses in everyday life would help advance the field. This article provides a pragmatic overview of approaches, opportunities, and challenges when intensive ambulatory methods are applied to study everyday stress responses in "real time." We distinguish between three stress-response components (i.e., reactivity, recovery, and pileup) and focus on several fundamental questions: (a) What is the appropriate stress-free resting state (or "baseline") for an individual in everyday life? (b) How does one index the magnitude of the initial response to a stressor (reactivity)? (c) Following a stressor, how can recovery be identified (e.g., when the stress response has completed)? and (d) Because stressors may not occur in isolation, how can one capture the temporal clustering of stressors and/or stress responses (pileup)? We also present initial ideas on applying this approach to intervention research. Although we focus on stress responses, these issues may inform many other dynamic intraindividual constructs and behaviors (e.g., physical activity, physiological processes, other subjective states) captured in ambulatory assessment.

Evaluating a pragmatic estimate of insulin sensitivity in Latino youth with obesity.

The whole-body insulin sensitivity index (WBISI) is a widely used surrogate of insulin sensitivity estimated from glucose and insulin concentrations during an oral glucose tolerance test (OGTT). The original WBISI uses five timepoints but reduced sampling models have been proposed. These reduced models have not been applied to the paediatric population. The purpose of this study is to compare cross-sectional agreement and changes in response to lifestyle intervention between the original WBISI and the WBISI120 using fasting and 2-hour glucose and insulin concentrations from OGTT among Latino adolescents with obesity. We also examined the cost-differential between the two measures. Secondary analyses were conducted with data from Latino adolescents (14-16 years) with obesity (BMI ≥ 95th percentile) who were recruited for a randomized controlled lifestyle intervention trial. Baseline data in youth (n = 148) who underwent a 2-hour OGTT was used to analyse agreement between WBISI and WBISI120 . Data from 65 participants who completed a 12-week lifestyle intervention were used to assess changes and the rate of change between WBISI and WBISI120 . Research costs to determine both measures were compared. WBISI120 showed good cross-sectional agreement (ICCagreement = 0.88) with the full WBISI. Following intervention, WBISI120 increased 62.5% (M ± SD, 1.6 ± 1.2 to 2.6 ± 1.7, P < .001) while WBISI increased by 25.0% (1.6 ± 1.0 to 2.0 ± 1.0, P < .001) but the rate of change for WBISI and WBISI120 was not significantly different (P = .11). WBISI120 costs ~70% less than WBISI. WBISI120 may offer a cost-effective surrogate estimate of insulin sensitivity in Latino youth with obesity.

Long-term effects of sit-stand workstations on workplace sitting: A natural experiment.

OBJECTIVE: Sit-stand workstations may result in significant reductions in workplace sitting. However, few studies have examined long-term maintenance under real-world conditions. The purpose of this study was to evaluate workplace sitting time, cardio-metabolic biomarkers, and work productivity during a workplace re-design which included the installation of sit-stand workstations. DESIGN: Natural experiment with appropriately matched comparison. METHODS: Office workers from distinct worksites in the same unit were recruited (Intervention, n=24; Comparison, n=12). Intervention arm participants received a sit-stand workstation and 4 months of sitting-specific motivational support. The comparison arm received 4 months of ergonomic focused motivational support. Time spent in sitting, standing, and other physical activity were measured by activPAL3c for a week. Cardio-metabolic biomarkers and work productivity were also measured. Assessments occurred at baseline, 4 months, and 18 months. RESULTS: At 4 months, work sitting time was reduced by 56.7±89.1min/8h workday (d=-0.64), relative to comparison. Standing time (37.4±69.2min/8h workday; d=0.54) and sit-to-stand transitions (3.3±0.4min/8h workday, d=0.44) were also improved relative to comparison. At 18 months, work sitting time reductions (52.6±68.3min/8h workday; d=-0.77) and standing time improvements (17.7±54.8min/8h workday, d=0.32) were maintained in the intervention group relative to comparison. Cardio-metabolic and work productivity changes were mixed; however, strongest effects favoring the intervention group were observed at 18 months. CONCLUSIONS: Sit-stand workstations, accompanied with behavioral support, were effective in reducing workplace and overall daily sitting and increasing standing time in a real-world setting. The effect appears to have been sustained for 18 months, with mixed results in cardio-metabolic and productivity outcomes.

Social ecological correlates of workplace sedentary behavior.

BACKGROUND: To identify social ecological correlates of objectively measured workplace sedentary behavior. METHODS: Participants from 24 worksites - across academic, industrial, and government sectors - wore an activPAL-micro accelerometer for 7-days (Jan-Nov 2016). Work time was segmented using daily logs. Sedentary behavior outcomes included time spent sitting, standing, in light intensity physical activity (LPA, stepping cadence <100 steps/min), and in prolonged sitting bouts (>30 min). Outcomes were standardized to an 8 h work day. Two electronic surveys were completed to derive individual (job type and work engagement), cultural (lunch away from the desk, walking at lunch and face-to-face interaction), physical (personal printer and office type) and organizational (sector) factors. Mixed-model analyses with worksite-level clustering were performed to examine multi-level associations. Secondary analyses examined job type and sector as moderators of these associations. All models were adjusted for age, race/ethnicity and gender. RESULTS: Participants (N = 478; 72% female; age: 45.0 ± 11.3 years; 77.8% non-Hispanic white) wore the activPAL-micro for 90.2 ± 15.5% of the reported workday. Walking at lunch was positively associated with LPA (5.0 ± 0.5 min/8 h, P < 0.001). Regular face-to-face interaction was negatively associated with prolonged sitting (-11.3 ± 4.8 min/8 h, P < 0.05). Individuals in private offices sat more (20.1 ± 9.1 min/8 h, P < 0.05), stood less (-21.5 ± 8.8 min/8 h, P < 0.05), and engaged in more prolonged sitting (40.9 ± 11.2 min/8 h, P < 0.001) than those in public office space. These associations were further modified by job type and sector. CONCLUSIONS: Work-specific individual, cultural, physical and organizational factors are associated with workplace sedentary behavior. Associations vary by job type and sector and should be considered in the design of workplace interventions to reduce sedentary behavior. TRIAL REGISTRATION: Clinical trial No. NCT02566317 ; Registered Sept 22nd 2015.

An intervention to reduce sitting and increase light-intensity physical activity at work: Design and rationale of the 'Stand & Move at Work' group randomized trial.

BACKGROUND: American workers spend 70-80% of their time at work being sedentary. Traditional approaches to increase moderate-vigorous physical activity (MVPA) may be perceived to be harmful to productivity. Approaches that target reductions in sedentary behavior and/or increases in standing or light-intensity physical activity [LPA] may not interfere with productivity and may be more feasible to achieve through small changes accumulated throughout the workday METHODS/DESIGN: This group randomized trial (i.e., cluster randomized trial) will test the relative efficacy of two sedentary behavior focused interventions in 24 worksites across two states (N=720 workers). The MOVE+ intervention is a multilevel individual, social, environmental, and organizational intervention targeting increases in light-intensity physical activity in the workplace. The STAND+ intervention is the MOVE+ intervention with the addition of the installation and use of sit-stand workstations to reduce sedentary behavior and enhance light-intensity physical activity opportunities. Our primary outcome will be objectively-measured changes in sedentary behavior and light-intensity physical activity over 12months, with additional process measures at 3months and longer-term sustainability outcomes at 24months. Our secondary outcomes will be a clustered cardiometabolic risk score (comprised of fasting glucose, insulin, triglycerides, HDL-cholesterol, and blood pressure), workplace productivity, and job satisfaction DISCUSSION: This study will determine the efficacy of a multi-level workplace intervention (including the use of a sit-stand workstation) to reduce sedentary behavior and increase LPA and concomitant impact on cardiometabolic health, workplace productivity, and satisfaction. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02566317 (date of registration: 10/1/2015).