Effects of Progressive Intensity Exercise Training on Glycemic Control in Older Adults

Study Overview
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Brief Summary
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The purpose of this study is to compare the effects of moderate versus vigorous intensity exercise training on glycemic control in older adults. Glycemic control will be assessed using an oral glucose tolerance test and continuous glucose monitors. In addition, the investigaotrs will investigate whether engaging in an exercise training program elicits changes in sedentary behavior, non-exercise physical activity, sleep, and total daily energy expenditure.

Detailed Description
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Approximately 25% of older adults have type 2 diabetes mellitus, and almost 50% of older adults have prediabetes. Identifying strategies to prevent the progression of diabetes in this older adult population is imperative. One strategy that has shown promise is lifestyle modification. As adults age they also increase sedentary behavior, decrease physical activity, and have increased occurrence of sleep problems. The combination of these lifestyle factors are likely responsible for the decreases in glycemic control with aging. The American Diabetes Association recommends that prediabetic adults, including older adults, increase structured aerobic exercise and incidental (non-exercise) physical activity while decreasing sedentary behavior. It is emphasized that structured exercise is the most important of these recommendations. However, initiating an exercise routine, may unintentionally affect time spent sitting, non-exercise physical activity, and other lifestyle behaviors like sleep. These changes may attenuate or enhance the effects of exercise on glycemic control. This study will compare the effects of moderate and high intensity exercise on glycemic control, and determine whether changes in non-exercise physical activity, sitting time, and sleep are associated with the observed changes. Because of the increasing prevalence of diabetes with age, identifying the optimal exercise prescription to preserve glycemic control in older adults has important clinical implications.

Official Title
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Effects of Progressive Intensity Exercise Training on Glycemic Control in Older Adults Who Are at Risk for Diabetes

Conditions
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PreDiabetes, Aging

Intervention / Treatment
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* Behavioral: Moderate Intensity Exercise Training (MOD)
* Behavioral: Vigorous Intensity Exercise Training (VIG)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥60 to <80 years upon study entry Body mass index ≥25.0 to <35.0 kg/m2 as measured at the baseline screening visit HBA1c ≥ 5.7% to <6.5% OR Fasting Glucose ≥ 100 to <126 mg/dl as measured at the baseline screening visit. Exclusion Criteria: History of metabolic, cardiac, or pulmonary disease that classifies the individual as high risk by the American College of Sports Medicine Participants with un-controlled hypertension and un-controlled thyroid disorders and are on medication for <3 months. Resting systolic blood pressure >160 mmHg or resting diastolic blood pressure >100 mmHg will be exclusionary. At the baseline screening visit, an initial resting blood pressure measurement will be attained after the participant is seated at rest for 5 minutes. Subsequent resting blood pressure measurements can be taken at the baseline screening visit up to 3 times to determine eligibility. Subsequent measurements will be taken under the same conditions as the initial measurement with a minimum of 5 minutes between readings. If more than one reading is needed to determine eligibility, the average of all readings taken will be used. Thyroid dysfunction, defined as an ultrasensitive thyroid stimulating hormone (TSH) <0.5 or >5.0 mU/L; volunteers with abnormal TSH values will be re-considered for participation in the study after follow-up evaluation by the PCP with initiation or adjustment of thyroid hormone replacement. Self-reported chronic Inflammatory Disease (e.g., rheumatoid arthritis, lupus) Currently taking statins, hormone replacement therapy, prescribed sleep medications, or medications that may affect heart rate response to exercise (e.g., beta blockers) Participating in >30 minutes of aerobic exercise/week during the past 3 months Inability to complete exercise test Sleep Apnea

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 79 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Moderate Exercise Training<br>Exercise training program that will focus on engaging in  150 minutes of moderate intensity exercise per week. Exercise will be supervised by trained staff. | Behavioral: Moderate Intensity Exercise Training (MOD)<br>* For the first 4 weeks, participant will be asked to complete 3 days of exercise/week at 50-65% heart rate maximum. Sessions will last between 30-40 minutes excluding the warm-up and cool down (5-10 minutes). After 4 weeks, the MOD group will be expected to match the exercise prescription. The exercise prescription for the MOD group for weeks 5-12 will be 4 days/week, 45 min/session completed at 60-65% heart rate maximum.<br>|
| Experimental: Vigorous Exercise Training<br>Exercise training program that will focus on engaging in  150 minutes of vigorous intensity exercise per week. Exercise will be supervised by trained staff. | Behavioral: Vigorous Intensity Exercise Training (VIG)<br>* The exercise lead in period will be the same as the moderate intensity exercise training program. After 6 weeks, the VIG group will be expected to match the exercise prescription. The exercise prescription for the VIG for weeks 7-12 will be 4 days/week, 45 min/session completed at 80-85% heart rate maximum.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Glucose Area Under the Curve (AUC) | Glucose will be assessed at 0, 10, 20, 30, 60, 90, 120, 180 minutes. These measurements will be used to calculate glucose AUC. | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Insulin Sensitivity Index (μmol·kg^-1·min^-1·pM^-1) | Glucose, insulin, and c-peptide will be assessed at 0, 10, 20, 30, 60, 90, 120, 180 minutes . Height will be measured using a wall mounted stadiometer (cm). Weight will be assessed using a digital scale (kg). Collectively these measurements will be used to calculate BMI (kg/m^2). All of these measurement will be used to assess Insulin sensitivity index as determined by the regression model validated by Stumvoll. | Baseline (0 weeks), Post Intervention (12 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Sedentary Time | Measured using a wearable device (min/day) | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Change in Non-Exercise Physical Activity | Measured using a wearable device (min/day) | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Change in Total Daily Energy Expenditure | Measured via doubly labeled water (kcals/day) | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Change in Sleep Duration - 1 | Measured using a wearable device | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Change in Sleep Duration - 2 | Measured using a questionnaire | Baseline (0 weeks), Post Intervention (12 weeks) | 
| Change in 24-hour Glycemic Control (glucose AUC) | Measured using a continuous glucose monitor (glucose AUC) | Baseline (0 weeks), Post Intervention (12 weeks) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Exercise, Physical activity, Blood glucose, Sleep