Physical Activity and Sedentary Behavior Change; Impact on Lifestyle

Diabetes Prevention Program translational efforts, such as the Group Lifestyle Balance Program (GLB), have been shown to be effective in reducing weight and modifying diabetes and CVD risk factors in a variety of diverse community settings. Although one of the two primary goals of these DPP translation programs focuses on increasing physical activity levels, few published DPP translation studies reported results on change in physical activity with only one study reporting activity levels from an objective measurement instrument. In order to completely understand the role that physical activity plays in making healthy lifestyle change, it is critical that we validate the impact of activity using a valid and reliable objective measure. In addition, current studies suggest that decreasing time spent sitting may have a positive health impact separate from the effects of participating in planned bouts of moderate intensity activity. Therefore, we propose to examine the impact of a modified version of the GLB program, which will focus on decreasing sedentary/sitting behaviors. The results of this project will provide information regarding best options for physical activity within lifestyle intervention programs, focusing both on verifying the current role of physical activity in lifestyle intervention using an objective measure and on examining an alternative intervention option for translation efforts.

Translation efforts based upon the successful Diabetes Prevention Program (DPP) have shown that this behavioral lifestyle intervention model is effective in a variety of diverse community settings. Despite the fact that physical activity is a key part of the DPP lifestyle intervention as one of the two intervention goals, activity change in the DPP, and/or the resulting translation studies modeled after it, has not been adequately verified with an accurate objective measure. In addition, previous research has shown that, in many subgroups of the general population, moderate and vigorous physical activity is non-existent. Individuals with activity only at the low end of the intensity spectrum may have a difficult time increasing their levels of moderate+ intensity physical activity for various reasons such as limited function or lack of motivation. For these individuals, interventions with a movement goal of increasing planned bouts of moderate intensity activity may not be as effective and therefore not as beneficial as interventions with a movement goal of decreasing time spent sitting.

The purpose of this proposal is to understand the impact of movement, specifically physical activity and sitting time, in a DPP-adapted community lifestyle intervention, Group Lifestyle Balance (GLB).

Aim 1: To determine if the GLB lifestyle intervention, shown to be effective in translation efforts in decreasing weight and increasing self-reported activity, has significant changes in physical activity levels determined by a validated objective measure, the accelerometer. It is hypothesized that participants randomized to the conventional lifestyle intervention arm (GLB-MOD) will have significant improvements in our primary endpoints of weight and physical activity (measured objectively) compared to a delayed-intervention control at 6 months and will have reductions in several secondary outcome measures (fasting glucose, insulin, blood pressure, waist, lipids, physical function, and quality of life).

Aim 2: To determine if a lifestyle intervention program similar to the one described above, with the only change being that the activity focus is now replaced with an inactivity focus (GLB-SED), is also effective. It is hypothesized that participants randomized to GLB-SED will have a significant improvement in the primary endpoints of weight and decreased inactivity (measured objectively) compared to a delayed-intervention control at 6 months and will have significant reductions in several of the secondary endpoints (fasting glucose, insulin, blood pressure, waist circumference, lipids, physical function, quality of life).

Secondary Aims: To examine the pre-post change in participants for weight, physical activity (objective and subjective), and sedentary time from baseline to 6 and 12 months of intervention for each randomized arm and to understand the inter-relationships of these behavioral factors over time. It is hypothesized that those GLB-MOD participants who achieve significant weight loss will also have significant increases in their moderate+ intensity activity levels. Similarly, we hypothesize those GLB-SED participants who achieve significant weight loss will also have significant decreases in the amount of time they spent sedentary/sitting. An estimate of the difference in participant cost between the two versions of the lifestyle intervention programs will also be determined.

Aim #1 addresses an important remaining gap in the prevention literature; does objectively measured activity improve as a result of the existing intervention that is being used in DPP-based translation efforts and does this change in activity have an impact on weight change? Aim #2 examines the impact of replacing the conventional physical activity goal of increasing planned and relatively brief bouts of moderate physical activity with one focusing on decreasing sedentary time within the framework of a successful translation lifestyle intervention adapted from the DPP, the Group Lifestyle Balance (GLB) program.

The study design is a prospective, six month delayed-control intervention in which 321 subjects (age 50 and older with a BMI of ≥24 kg/m2 and with prediabetes and/or metabolic syndrome) will be recruited from community centers and randomly assigned to one of three groups: the standard GLB program which includes the conventional moderate activity goal (GLB-MOD), the GLB program with a focus on decreasing sedentary behavior (GLB-SED), or delayed intervention. Subjects assigned to GLB-MOD and GLB-SED will each, separately be compared at 6 months to the delayed-control group after which time, the delayed group will be randomly assigned to either GLB-MOD or GLB-SED. Participants will complete baseline, 6, and 12 month assessment visits. Change in weight, objectively measured activity, and time spent sedentary are the primary outcomes with secondary outcomes including change in self-reported physical activity, HbA1c, fasting glucose, lipids, blood pressure, waist circumference, quality of life and physical function.

It is hypothesized that physical activity assessed by accelerometry in GLB-MOD will significantly increase (mostly moderate intense activity) and that there will be a significant decrease in weight, which will partly be related to change in activity levels. The 2nd hypothesis is that the GLB-SED intervention will significantly decrease time spent sitting as measured by accelerometry and that this change will also be related to a significant decrease in weight. The information that will be gained from this entire effort is important, innovative, and will allow us to obtain a complete and accurate understanding of both ends of the physical activity/inactivity spectrum and their impact in community prevention intervention programs. If shown to be effective, the innovative, modified sedentary-focused translation intervention program would provide a valuable future translation option.

Eligibility Criteria:
Inclusion Criteria:

Individuals attending screening who are found to have prediabetes AND/OR the metabolic syndrome are eligible to participate in the intervention. Pre-diabetes is defined as having a fasting glucose \>100 mg/dL and \<126mg/dL and/or a hemoglobin A1C of 5.7%-6.4%.

Metabolic syndrome is defined as having at least 3 of the 5 following risk factors:

1. Waist circumference (\>40 inches men, \>35 inches women);
2. Blood pressure \>130 mmHg (systolic) or \>85 mmHg (diastolic) OR history of diagnosed hypertension
3. Low HDL level (\<40mg/dL men, \<50 mg/dL women)
4. Elevated triglyceride level \>150 mg/dL
5. Fasting glucose \>100mg/dL and \<126mg/dL

Individuals attending screening with hyperlipidemia plus one additional component of the metabolic syndrome are also eligible.

Exclusion Criteria:

Individuals who are identified as having diabetes as a result of the screening are not eligible. All individuals enrolled in the study should have at least 6th grade English reading/writing ability. Physician approval will be requested to clear for the activity portion of the program.