Sarah L. Mullane

Effects of standing and light-intensity activity on ambulatory blood pressure

PURPOSE This study aimed to compare ambulatory blood pressure (ABP) response to accumulated standing (STAND), cycling (CYCLE), and walking (WALK) to a sitting-only (SIT) day in adults. METHODS Nine overweight or obese (body mass index, 28.7 ± 2.7 kg · m(-2)) adults (30 ± 15 yr) participated in this randomized crossover full-factorial study. Four conditions (WALK, STAND, CYCLE, and SIT) were randomly performed 1 wk apart. WALK, STAND, and CYCLE conditions consisted of progressively increasing activity time to accumulate 2.5 h during an 8-h simulated workday. WALK (1.0 mph) and STAND (0.0 mph) were completed on a treadmill placed underneath a standing-height desk. During CYCLE, participants pedaled on a Monark cycle ergometer at a cadence and energy expenditure equivalent to WALK. Participants remained seated during the SIT condition. Participants wore an ABP cuff from 0800 h until 2200 h on all conditions. Linear mixed models were used to test condition differences in systolic (SBP) and diastolic (DBP) blood pressure. Chi-square was used to detect frequency difference of BP load. RESULTS There was a whole-day (during and after work hours) SBP and DBP treatment effect (P < 0.01). Systolic blood pressure during STAND (132 ± 17 mm Hg), WALK (133 ± 17 mm Hg), and CYCLE (130 ± 16 mm Hg) were lower compared with that during SIT (137 ± 17 mm Hg) (all P < 0.01). CYCLE was lower than STAND (P = 0.04) and WALK (P < 0.01). For DBP, only CYCLE (69 ± 12 mm Hg) was lower than SIT (71 ± 13 mm Hg; P < 0.01). Compared with SIT, WALK, STAND, and CYCLE reduced SBP load by 4%, 4%, and 13%, respectively (all P < 0.01). CONCLUSIONS Compared with sitting, accumulating 2.5 h of light-intensity physical activity or standing during an 8-h workday may reduce ABP during and after work hours.

Effects of Standing and Light-Intensity Walking and Cycling on 24-h Glucose.

PURPOSE This study aimed to compare 24-h and postprandial glucose responses to incremental intervals of standing (STAND), walking (WALK), and cycling (CYCLE) to a sit-only (SIT) condition. METHODS Nine overweight/obese (body mass index = 29 ± 3 kg·m) adults (30 ± 15 yr) participated in this randomized crossover full-factorial study, with each condition performed 1 wk apart. STAND, CYCLE, and WALK intervals increased from 10 to 30 min·h (2.5 h total) during an 8-h workday. WALK (1.0 mph) and STAND were matched for upright time, and WALK and CYCLE were matched for energy expenditure (~2 METs). Continuous interstitial glucose monitoring was performed for 24 h to include the 8-h workday (LAB), after-work evening hours (EVE), and sleep (SLEEP). Three 2-h postprandial periods were also analyzed. Linear mixed models were used to test for condition differences. RESULTS Compared with SIT (5.7 ± 1.0 mmol·L), mean 24-h glucose during STAND (5.4 ± 0.9 mmol·L) and WALK (5.3 ± 0.9 mmol·L) were lower, and CYCLE (5.1 ± 1.0 mmol·L) was lower than all other conditions (all P < 0.001). During LAB and EVE, mean glucose was lower for STAND, WALK, and CYCLE compared with SIT (P < 0.001). During SLEEP, the mean glucose for CYCLE was lower than all other conditions (P < 0.001). Compared with SIT, cumulative 6-h postprandial mean glucose was 5%-12% lower (P < 0.001) during STAND, WALK, and CYCLE, and 6-h postprandial glucose integrated area under the curve was 24% lower during WALK (P < 0.05) and 44% lower during CYCLE (P < 0.001). CONCLUSIONS Replacing sitting with regular intervals of standing or light-intensity activity during an 8-h workday reduces 24-h and postprandial glucose. These effects persist during evening hours, with CYCLE having the largest and most sustained effect.

Acute effects on cognitive performance following bouts of standing and light-intensity physical activity in a simulated workplace environment

OBJECTIVES To compare acute cognitive effects following bouts of standing (STAND), cycling (CYCLE) and walking (WALK) to a sit-only (SIT) condition. DESIGN Randomized cross-over full-factorial study. METHODS Nine overweight (BMI=29±3kg/m2) adults (30±15years; 7 females, 2 males) completed four conditions (SIT, STAND, WALK and CYCLE) across a 6h period with a 7days washout period between conditions. SIT consisted of uninterrupted sitting. Experimental conditions included intermittent bouts of standing (STAND), cycling (CYCLE) and walking (WALK). A cognitive performance battery (Cogstate) was completed twice in a seated position following bouts of standing and light-intensity physical activity. Mixed-effects models compared between-condition differences in standardized score (z-score), accuracy (%), and speed (log10ms). RESULTS Cognitive performance z-score and accuracy measures were higher during STAND, CYCLE and WALK (P<0.05) conditions compared to the SIT condition. CYCLE was better than other experimental conditions. CONCLUSIONS Compared to uninterrupted sitting, short bouts of standing or light-intensity cycling and walking may improve acute cognitive performance.

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).

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.

Sedentary Behaviour at the Community Level: Correlates, Theories, and Interventions

This chapter provides a succinct overview of sedentary behaviour correlates, theories, and interventions in youth communities (schools), adult communities (worksites), and neighbourhoods. Within each community, we identify and discuss (a) observational and experimental studies examining the correlates of sedentary behaviour; (b) demographic, psychosocial, and environmental factors that influence sedentary behaviour; and (c) intervention designs and outcomes targeting sedentary behaviour. How technological advances and media influence may impact public awareness and intervention design is discussed. We also highlight the roles and responsibilities of both research and public health organizations to promote healthy behaviours. Finally, we evaluate community-based interventions to provide recommendations and future directions. We conclude that the barriers and challenges faced at the community level for reducing sedentary behaviours may vary per community setting and type. Ultimately, multilevel strategies and collaborative practices, across multiple settings that target sedentary behaviour as an independent risk factor, are needed to improve the efficacy of community-level interventions and increase the potential for future dissemination.

Enrollment Strategies, Barriers to Participation, and Reach of a Workplace Intervention Targeting Sedentary Behavior

Purpose: To review enrollment strategies, participation barriers, and program reach of a large, 2-year workplace intervention targeting sedentary behavior. Approach: Cross-sectional, retrospective review. Setting: Twenty-four worksites balanced across academic, industry, and government sectors in Minneapolis/Saint Paul (Minnesota) and Phoenix (Arizona) regions. Participants: Full-time (≥30+ h/wk), sedentary office workers. Methods: Reach was calculated as the proportion of eligible employees who enrolled in the intervention ([N enrolled/(proportion of eligible employees × N total employees)] × 100). Mean (1 standard deviation) and median worksite sizes were calculated at each enrollment step. Participation barriers and modifications were recorded by the research team. A survey was sent to a subset of nonparticipants (N = 57), and thematic analyses were conducted to examine reasons for nonparticipation, positive impacts, and negative experiences. Results: Employer reach was 65% (56 worksites invited to participate; 66% eligible of 56 responses; 24 enrolled). Employee reach was 58% (1317 invited to participate, 83% eligible of 906 responses; 632 enrolled). Postrandomization, on average, 59% (15%) of the worksites participated. Eighteen modifications were developed to overcome participant-, context-, and research-related participation barriers. Conclusion: A high proportion of worksites and employees approached to participate in a sedentary behavior reduction intervention engaged in the study. Interventions that provide flexible enrollment, graded participant engagement options, and adopt a participant-centered approach may facilitate workplace intervention success.

Feasibility and Parental Acceptability of an 8-Week, Slow-Speed, High-Intensity, Community-Based Resistance Training Program for Preadolescent Children

High-intensity resistance training (RT) shows promise for improved cardiometabolic health in children. Achieving high-intensity RT safely is a challenge for community-based programs because of parental concerns and group engagement. Twenty preadolescent children completed an 8-week, twice per week program using slow speed to achieve high-intensity RT. Parent and child surveys were conducted to measure acceptability and effectiveness. Child fitness levels were assessed, and fasting blood draws and dual-energy x-ray absorptiometry were performed on a subset population. Perceived RT safety, self-efficacy, body composition, waist circumference, and fitness tests exhibited significant improvements. Using slow speed to achieve high-intensity RT may provide a safe and effective community-based alternative for preadolescents.