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Open Access Publications from the University of California

Scholarly Works (15 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2017)

Background: Society is sitting more than ever before. Large-scale epidemiological evidence indicates that prolonged sitting time has negative health impacts including increased risk of metabolic syndrome, heart disease, weight gain, cancer, and premature mortality. Older adults are an important population to target because they represent the most sedentary segment of the population who struggle to meet activity guidelines. Based on these negative health associations, research on sedentary behavior interventions, especially focused on older adults, is a public health priority.

Methods: This dissertation uses data from a pilot sedentary behavior intervention in 30 adults aged 50-70 years to understand how to measure and prompt sedentary behavior change. The intervention successfully targeted two distinct sitting interruption modalities (i.e., sit less, increase sit-to-stand transitions). Chapter 1 explored differences in self-reported and objectively-measured sitting time to evaluate participants’ ability to self-assess behavior during an intervention. Chapter 2 included a mixed methods analysis of tool use to disrupt sitting time during the pilot intervention. Chapter 3 used focus groups to explore participants’ perceptions regarding wearable devices to track and change sedentary behavior.

Results: Chapter 1 found significant differences in self-reported sitting time by day of week, employment status, and participation in a sedentary behavior intervention. Chapter 2 showed that participants who used effective tools were most successful in reducing sitting time. In contrast, current tools for increasing sit-to-stand transitions were ineffective. The focus groups from Chapter 3 revealed that participants were amenable to using wearable devices; however, current devices lack key features necessary for sedentary behavior including the ability to accurately measure sitting time and distinguish “inactivity” from standing.

Discussion: Given the negative health outcomes associated with excessive sitting, more interventions are targeting sedentary behavior. The three themes explored in this dissertation (specificity of measurement, tools, and behaviors) and the combination of analysis methods help increase our understanding of sedentary behavior in older adults. This dissertation provides recommendations to improve the field by using specific measures for sitting time to capture differences across the week, designing interventions to include tools with a specific focus on sedentary behavior, and exploring how technology can help change behavior.

    Cover page: Take a Stand: A Mixed Methods Approach to Evaluate a Pilot Sedentary Behavior Intervention
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2019)
    PURPOSE: Cancer survivors are highly sedentary and have low physical activity. How physical activity interventions impact sedentary behavior remains unclear. This secondary analysis examined changes in sedentary behavior among breast cancer survivors participating in a physical activity intervention that significantly increased moderate-to-vigorous physical activity (MVPA). METHODS: Insufficiently active breast cancer survivors were randomized to a 12-week physical activity intervention (exercise arm) or control arm. The intervention focused solely on increasing MVPA with no content targeting sedentary behavior. Total sedentary behavior, light physical activity (LPA), and MVPA were measured at baseline and 12 weeks (ActiGraph GT3X+ accelerometer). Separate linear mixed-effects models tested intervention effects on sedentary behavior, intervention effects on LPA, the relationship between change in MVPA and change in sedentary behavior, and potential moderators of intervention effects on sedentary behavior. RESULTS: The exercise arm had significantly greater reductions in sedentary behavior than the control arm (mean - 24.9 min/day (SD = 5.9) vs. - 4.8 min/day (SD = 5.9), b = - 20.1 (SE = 8.4), p = 0.02). Larger increases in MVPA were associated with larger decreases in sedentary behavior (b = - 1.9 (SE = 0.21), p < 0.001). Women farther out from surgery had significantly greater reductions in sedentary behavior than women closer to surgery (b = - 0.91 (SE = 0.5), p = 0.07). There was no significant group difference in change in LPA from baseline to 12 weeks (b = 5.64 (SE = 7.69), p = 0.48). CONCLUSIONS: Breast cancer survivors in a physical activity intervention reduced total sedentary time in addition to increasing MVPA. IMPLICATIONS FOR CANCER SURVIVORS: Both increasing physical activity and reducing sedentary behavior are needed to promote optimal health in cancer survivors. These results show that MVPA and sedentary behavior could be successfully targeted together, particularly among longer-term cancer survivors. CLINICAL TRIAL REGISTRATION: This study is registered at www.ClinicalTrials.gov (NCT02332876).
      Cover page: Breast cancer survivors reduce accelerometer-measured sedentary time in an exercise intervention.
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2018)
      UNLABELLED: This paper reports on the findings and recommendations specific to older adults from the Tech Summit: Innovative Tools for Assessing Diet and Physical Activity for Health Promotion forum organized by the North American branch of the International Life Sciences Institute. The summit aimed to investigate current and emerging challenges related to improving energy balance behavior assessment and intervention via technology. The current manuscript focuses on how novel technologies are applied in older adult populations and enumerated the barriers and facilitators to using technology within this population. Given the multiple applications for technology in this population, including the ability to monitor health events and behaviors in real time, technology presents an innovative method to aid with the changes associated with aging. Although older adults are often perceived as lacking interest in and ability to adopt technologies, recent studies show they are comfortable adopting technology and user uptake is high with proper training and guided facilitation. Finally, the conclusions suggest recommendations for future research, including the need for larger trials with clinical outcomes and more research using end-user design that includes older adults as technology partners who are part of the design process. THEME INFORMATION: This article is part of a theme issue entitled Innovative Tools for Assessing Diet and Physical Activity for Health Promotion, which is sponsored by the North American branch of the International Life Sciences Institute.
        Cover page: Diet and Activity Assessments and Interventions Using Technology in Older Adults.
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2019)

        Objective

        The authors investigated if the physical activity increases observed in the Multilevel Intervention for Physical Activity in Retirement Communities (MIPARC) improved cognitive functions in older adults. The authors also examined if within-person changes in moderate to vigorous physical activity (MVPA), as opposed to low-light and high-light physical activity, were related to cognitive improvements in the entire sample.

        Methods

        This was a cluster randomized control trial set in retirement communities in San Diego County, CA. A total of 307 older adults without a formal diagnosis of dementia (mean age: 83 years; age range: 67-100; standard deviation: 6.4 years; 72% women) were assigned to the physical activity (N = 151) or healthy education control (N = 156) groups. Interventions were led by study staff for the first 6 months and sustained by peer leaders for the next 6 months. Components included individual counseling and self-monitoring with pedometers, group education sessions, and printed materials. Measurements occurred at baseline, 6 months, and 12 months. Triaxial accelerometers measured physical activity for 1 week. The Trail Making Test (TMT) Parts A and B and a Symbol Search Test measured cognitive functions.

        Results

        There were no significant differences in cognitive functions between the MIPARC intervention and control groups at 6 or 12 months. Within-person increases in MVPA, and not low-light or high-light physical activity, were associated with improvements in TMT Parts B, B-A, and Symbol Search scores in the entire sample.

        Conclusion

        Findings suggest that MVPA may have a stronger impact on cognitive functions than lower intensity physical activity within retirement community samples of highly educated older adults without dementia.
          Cover page: Changes in Moderate Intensity Physical Activity Are Associated With Better Cognition in the Multilevel Intervention for Physical Activity in Retirement Communities (MIPARC) Study
          • Article
          • Peer Reviewed
          Publications (2018)
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2019)

            Purpose

            Cancer survivors are highly sedentary and have low physical activity. How physical activity interventions impact sedentary behavior remains unclear. This secondary analysis examined changes in sedentary behavior among breast cancer survivors participating in a physical activity intervention that significantly increased moderate-to-vigorous physical activity (MVPA).

            Methods

            Insufficiently active breast cancer survivors were randomized to a 12-week physical activity intervention (exercise arm) or control arm. The intervention focused solely on increasing MVPA with no content targeting sedentary behavior. Total sedentary behavior, light physical activity (LPA), and MVPA were measured at baseline and 12 weeks (ActiGraph GT3X+ accelerometer). Separate linear mixed-effects models tested intervention effects on sedentary behavior, intervention effects on LPA, the relationship between change in MVPA and change in sedentary behavior, and potential moderators of intervention effects on sedentary behavior.

            Results

            The exercise arm had significantly greater reductions in sedentary behavior than the control arm (mean - 24.9 min/day (SD = 5.9) vs. - 4.8 min/day (SD = 5.9), b = - 20.1 (SE = 8.4), p = 0.02). Larger increases in MVPA were associated with larger decreases in sedentary behavior (b = - 1.9 (SE = 0.21), p < 0.001). Women farther out from surgery had significantly greater reductions in sedentary behavior than women closer to surgery (b = - 0.91 (SE = 0.5), p = 0.07). There was no significant group difference in change in LPA from baseline to 12 weeks (b = 5.64 (SE = 7.69), p = 0.48).

            Conclusions

            Breast cancer survivors in a physical activity intervention reduced total sedentary time in addition to increasing MVPA.

            Implications for cancer survivors

            Both increasing physical activity and reducing sedentary behavior are needed to promote optimal health in cancer survivors. These results show that MVPA and sedentary behavior could be successfully targeted together, particularly among longer-term cancer survivors.

            Clinical trial registration

            This study is registered at www.ClinicalTrials.gov (NCT02332876).
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2020)

              Background

              For breast cancer survivors, moderate to vigorous physical activity (MVPA) is associated with improved survival. Less is known about the interrelationships of daytime activities (sedentary behavior [SB], light-intensity physical activity, and MVPA) and associations with survivors' health outcomes. This study will use isotemporal substitution to explore reallocations of time spent in daytime activities and associations with cancer recurrence biomarkers.

              Methods

              Breast cancer survivors (N = 333; mean age 63 y) wore accelerometers and provided fasting blood samples. Linear regression models estimated the associations between daytime activities and cancer recurrence biomarkers. Isotemporal substitution models estimated cross-sectional associations with biomarkers when time was reallocated from of one activity to another. Models were adjusted for wear time, demographics, lifestyle factors, and medical conditions.

              Results

              MVPA was significantly associated with lower insulin, C-reactive protein, homeostatic model assessment of insulin resistance, and glucose, and higher sex hormone-binding globulin (all P < .05). Light-intensity physical activity and SB were associated with insulin and homeostatic model assessment of insulin resistance (both P < .05). Reallocating 18 minutes of SB to MVPA resulted in significant beneficial associations with insulin (-9.3%), homeostatic model assessment of insulin resistance (-10.8%), glucose (-1.7%), and sex hormone-binding globulin (7.7%). There were no significant associations when 79 minutes of SB were shifted to light-intensity physical activity.

              Conclusions

              Results illuminate the possible benefits for breast cancer survivors of replacing time spent in SB with MVPA.
                Cover page: Using Isotemporal Analyses to Examine the Relationships Between Daytime Activities and Cancer Recurrence Biomarkers in Breast Cancer Survivors.
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2016)
                The main purpose of the present study was to assess the impact of global positioning system (GPS) signal lapse on physical activity analyses, discover any existing associations between missing GPS data and environmental and demographics attributes, and to determine whether imputation is an accurate and viable method for correcting GPS data loss. Accelerometer and GPS data of 782 participants from 8 studies were pooled to represent a range of lifestyles and interactions with the built environment. Periods of GPS signal lapse were identified and extracted. Generalised linear mixed models were run with the number of lapses and the length of lapses as outcomes. The signal lapses were imputed using a simple ruleset, and imputation was validated against person-worn camera imagery. A final generalised linear mixed model was used to identify the difference between the amount of GPS minutes pre- and post-imputation for the activity categories of sedentary, light, and moderate-to-vigorous physical activity. Over 17% of the dataset was comprised of GPS data lapses. No strong associations were found between increasing lapse length and number of lapses and the demographic and built environment variables. A significant difference was found between the pre- and postimputation minutes for each activity category. No demographic or environmental bias was found for length or number of lapses, but imputation of GPS data may make a significant difference for inclusion of physical activity data that occurred during a lapse. Imputing GPS data lapses is a viable technique for returning spatial context to accelerometer data and improving the completeness of the dataset.
                  • Article
                  • Peer Reviewed
                  UC San Diego Previously Published Works (2021)
                  This study employed novel GPS methods to assess the effect of a multilevel physical activity (PA) intervention on device-measured walking locations in 305 community dwelling older adults, ages 65+ (mean age = 83, 73% women). Retirement communities were randomized to a 1-year PA intervention that encouraged neighborhood walking, or to a healthy aging control condition. Total time and time spent walking in four life-space domains were assessed using GPS and accelerometer devices. The intervention increased the time spent walking as a proportion of total time spent in the Campus, Neighborhood and Beyond Neighborhood domains. Intervention effects on walking location were observed in both genders and across physical and cognitive functioning groups. Results demonstrate that an intervention providing individual, social and environmental support for walking can increase PA in larger life-space domains for a broad spectrum of older adults.
                    Cover page: Change in GPS-assessed walking locations following a cluster-randomized controlled physical activity trial in older adults, results from the MIPARC trial
                    • Article
                    • Peer Reviewed
                    UC San Diego Previously Published Works (2018)
                    BACKGROUND:Older adults are the least active population group. Interventions in residential settings may support a multi-level approach to behavior change. METHODS:In a cluster randomized control trial, 11 San Diego retirement communities were assigned to a physical activity (PA) intervention or a healthy aging attention control condition. Participants were 307 adults over 65 years old. The multilevel PA intervention was delivered with the assistance of peer leaders, who were trained older adult from the retirement communities. Intervention components included individual counseling & self-monitoring with pedometers, group education sessions, group walks, community advocacy and pedestrian community change projects. Intervention condition by time interactions were tested using generalized mixed effects regressions. The primary outcomes was accelerometer measured physical activity. Secondary outcomes were blood pressure and objectively measured physical functioning. RESULTS:Over 70% of the sample were 80 years or older. PA significantly increased in the intervention condition (56 min of moderate-vigorous PA per week; 119 min of light PA) compared with the control condition and remained significantly higher across the 12 month study. Men and participants under 84 years old benefited most from the intervention. There was a significant decrease in systolic (p < .007) and diastolic (p < .02) blood pressure at 6 months. Physical functioning improved but the changes were not statistically significant. CONCLUSIONS:Intervention fidelity was high demonstrating feasibility. Changes in PA and blood pressure achieved were comparable to other studies with much younger participants. Men, in particular, avoided a year-long decline in PA. TRIAL REGISTRATION:clincialtrials.gov Identifier: NCT01155011 .
                      Cover page: Cluster randomized controlled trial of a multilevel physical activity intervention for older adults
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