| dc.description.abstract | Sedentary behavior is a major health issue in people with type 2 diabetes (T2D). Many people with T2D are sedentary despite strong recommendations of regular physical activity. Studies that investigate the complex nature of sedentary behavior in people with T2D are still in their early stages. The overall purpose of this project was to investigate the general health impact of sedentary behavior on people with T2D. Specifically, three areas of research were identified as the primary focus of this dissertation. First, to examine the test-retest reliability of sedentary behavior measured via objective measures that are uniquely capable of detecting postural allocation (i.e. sitting vs standing or walking). Second, to assess the association of objective modifiable factors, glycemic control and physical function, and subjective health perception, fatigue and well-being, with sedentary behavior. Lastly, the feasibility and effectiveness of behavioral interventions aimed to decrease sedentary behavior in people with T2D were tested. Chapter one describes the results of a systematic review of randomized clinical trials (RCTs) that used objective measurement of activity to determine the outcome of interventions promoted daily physical activity in sedentary people with T2D. Two databases, PubMed and CINAHL, were searched for eligible studies using the following search terms: sedentary, diabetes, pedometer, physical activity, and accelerometer. A total of 15 RCTs were identified that investigated objectively measured daily physical activity in people with T2D. Multiple interventions such as behavioral/cognitive consultation and motivational phone calls promoting physical activity demonstrated improvement in physical activity level during the intervention period. The results of this review indicated that different interventional strategize can leads to temporary improvement in physical activity, however, interventions that produce long-term increases in physical activity and decreases in sedentary behavior are still scarce. Building upon the results from the above systematic review and the recommendations of a four session workshop sponsored by the National Heart, Lung, and Blood Institute and National Institute on ageing entitled Sedentary Behavior: Identifying Research Priorities 1, 2; we surmise the importance of establishing the test-retest reliability of activity monitors, activPALTM, in measuring habitual sedentary behavior and physical activity. Chapter two describes the result from examining the test-retest reliability of an activPALTM activity monitor in measuring sedentary behavior and physical activity in people with T2D aged 50 to 75 years old. Habitual sedentary behavior and physical activity data from two 7-day time periods of assessment separated by at least one week were obtained and intraclass correlation coefficient (ICC) was utilized to compare the two time points. Thirty participants completed the study. Both sedentary time and standing times exhibit high reliability, while step count and transitions from sit to stand demonstrated very high reliability. These results indicate stability in the measurement of sedentary behavior and physical activity in people with T2D over time using an activPALTM activity monitor. Thus, we concluded that activPALTM devices might be used as objective assessment of sedentary behavior and physical activity and detect changes in activity level in pre-post intervention designs. Examining sedentary behavior in further detail, multiple linear regression models were built to investigate the relationship between sedentary behavior and number of transitions from sit to stand with glycemic control, physical function, fatigue, and well-being in people with T2D. As described in chapter three, sedentary behavior data measured using activPALTM obtained from 59 individuals with T2D, aged 50 to 75 years old. Analysis of the data demonstrated the significant positive association of glycemic control with sedentary behavior independent of moderate to vigorous physical activity (MVPA). Furthermore, it showed that higher physical function levels tended to predict the association with higher number of transitions from sit to stand. Fatigue and well-being showed no significant association with either sedentary behavior or transitions from sit to stand. The results from this chapter demonstrated that glycemic control predicted sedentary behavior level. Furthermore, it highlighted the need to establish the direction of the association between glycemic control and sedentary behavior. In addition, there is a need to identify other modifiable health factors as these variables could be used as a main target for interventions aimed to improve health outcomes in people with T2D. In the last experimental chapter, chapter four, the results from the feasibility and efficacy of combined sedentary behavior counseling and vibrotactile sensory feedback on sedentary time and physical activity (steps count) in people with T2D are described. Ten community-dwelling sedentary adults completed the 3 months intervention consisting of sedentary behavior counseling (SB education and a motivational interviewing-informed) aided by an activity monitor with vibrotactile feature (activPAL3TM). Participants received sedentary behavior counseling at the end of weeks one, five, and nine; while they received the vibrotactile sensory feedback from the activity monitor at weeks five and nine. After study completion the intervention appeared to be feasible with 100% compliance and only 2 out of 10 participants reporting mild to moderate issues with activity monitor tolerability such skin irritation. However, these tolerability concern did not lead to either serious adverse events or the removal of the activity monitor. Furthermore, the pre – post assessment analysis of sedentary behavior and physical activity via paired t test or Wilcoxon matched pair signed-rank test showed that the intervention was effective in decreasing sedentary behavior and increasing physical activity, in addition to improvements in glycemic control. These findings suggested the promising effect of intervention aimed to decrease sedentary behavior in people with T2D in improving health outcomes. Larger sample size and randomized clinical trial design studies are warranted to examine the full extent of the intervention in the future. In summary, the results from this dissertation project found that people with T2D demonstrated stable levels of sedentary behavior and physical activity over 2-time periods. These stable levels of activity can be improved after the completion of 3-months behavioral modification intervention. Furthermore, sedentary behavior and glycemic control demonstrated a positive relationship independent of MVPA, and glycemic control improved after the compilation of a behavioral intervention aimed to decrease sedentary behavior and increase physical activity. Overall, sedentary behavior appears to negatively influence glycemic control and short-term intervention can offset the effects of sedentary behavior. However, the long-term effect of this intervention is still unclear. The obtained results indicate the need for future research investigating the full impact of sedentary behavior in people with T2D independent of physical activity, as being physically active does not necessary exclude high levels of sedentary behavior. Further, there is a need to investigate possible clinical applications for managing T2D and preventing detrimental health complications associated with T2D and sedentary behavior. [1] Rosenberg DE, Lee IM, Young DR, Prohaska TR, Owen N, Buchner DM. Novel strategies for sedentary behavior research. Medicine and science in sports and exercise. 2015;47:1311-5. [2] Thyfault JP, Du M, Kraus WE, Levine JA, Booth FW. Physiology of sedentary behavior and its relationship to health outcomes. Medicine and science in sports and exercise. 2015;47:1301-5. | |
