The purpose of the study is to determine if a 6-week exercise training program promotes exercise-induced metabolic flexibility, that is, the ability to switch fuel sources for energy, in older prediabetic adults.
This is an investigator initiated single group intervention trial. All participants will receive a 6-week exercise training program with testing occurring before and following the training program. Participants will be provided with 3 days of a high fat diet prior to each of the three testing sessions at the Clinical Research Unit. All who agree to participate will undergo the same intervention. The goal of this proposal is to study the impact of a 6-week moderate intensity walking training program on exercise induced lipid metabolic flexibility in older adults with prediabetes. Study Investigators will seek to determine if exercise induced lipid oxidation following a high fat diet is increased in trained individuals relative to their baseline.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
10
Participants will walk at 50% Heart Rate Reserve (HRR) 3 to 5 days per week for 6 weeks at the Department of Health and Exercise Science Clinical Research Center under the supervision of study staff.
Prior to the submaximal exercise testing visits, all participants will be provided with 3 days of a standardized isoenergetic high fat diet (20% of kcals from carbohydrate, 65% fat; 15% protein) to promote lipid oxidation. The meals will be prepared and provided by the Clinical Research Unit of Wake Forest Baptist Health. Participants will pick up 3 days' worth of food and snacks 4 days prior the testing visit. For the 3 days leading up to the visit, participants will eat the provided foods and complete a compliance assessment.
Department of Health and Exercise Science Clinical Research Center
Winston-Salem, North Carolina, United States
Wake Forest Baptist Medical Center Clinical Research Unit
Winston-Salem, North Carolina, United States
Metabolic Rate-Baseline
Metabolic rate will be measured by gas exchange using indirect calorimeter. For the first (baseline test) and second (follow up test 1) time we monitor gas exchange, participants will exercise for 20 minutes at a workload that elicits 50% of maximal oxygen consumption as determined by Graded Exercise Test #1 done before the exercise training program. The third time (follow up test 2), participants will exercise for 20 minutes at a workload that elicits 50% of oxygen consumption as determined by Graded Exercise Test #2 done after the exercise training program.
Time frame: Baseline
Metabolic Rate_6 weeks after exercise training program
Metabolic rate will be measured by gas exchange using indirect calorimeter. For the first (baseline test) and second (follow up test 1) time we monitor gas exchange, participants will exercise for 20 minutes at a workload that elicits 50% of maximal oxygen consumption as determined by Graded Exercise Test #1 done before the exercise training program. The third time (follow up test 2), participants will exercise for 20 minutes at a workload that elicits 50% of oxygen consumption as determined by Graded Exercise Test #2 done after the exercise training program.
Time frame: 6 weeks exercise training program
Blood collection_lactate Baseline
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of lactate. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: Baseline
Blood collection_lactate follow up 1
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of lactate. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 6 weeks exercise training program
Blood collection_lactate follow up 2
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At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of lactate. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 3-10 days following Follow-Up Test 1
Blood collection_glucose baseline
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of glucose. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: Baseline
Blood collection_glucose follow up 1
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of glucose. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 6 weeks exercise training program
Blood collection_glucose follow up 2
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of glucose. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 3-10 days following Follow-Up Test 1
Blood collection_nonesterified fatty acids
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of nonesterified fatty acids. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: Baseline
Blood collection_nonesterified fatty acids follow up 1
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of nonesterified fatty acids. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 6 weeks exercise training program
Blood collection_nonesterified fatty acids follow up 2
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of nonesterified fatty acids. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 3-10 days following Follow-Up Test 1
Blood collection_insulin
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of insulin. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: Baseline
Blood collection_insulin follow up 1
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of insulin. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 6 weeks exercise training program
Blood collection_insulin follow up 2
At baseline and follow-up testing visits, 6 blood samples at each visit (times 0, 5, 10, 15, 20, and 50) will be obtained for measures of insulin. Blood draws will happen as gas exchange is being measured. 1 tsp of blood will be taken through a catheter at each time point.
Time frame: 3-10 days following Follow-Up Test 1
VO2 peak
The gold standard for assessing cardiovascular fitness is exercise capacity as determined from peak volume of oxygen consumption (VO2peak) and treadmill time during a graded exercise test. A physician supervised, individualized ramp treadmill protocol will be performed on each participant. In this protocol, participants walk at a brisk pace with the speed based on their comfort and fitness. For lower fit individuals, the grade will be increased at a rate of 1%/minute, and for higher fit individuals, the grade will be increased at a rate of 2%/minute. The treadmill test will be performed according to guidelines set by the American College of Sports Medicine (ACSM, 2014), to evaluate the subject's cardiovascular response to exercise.
Time frame: Baseline (Pre-exercise training)
VO2 peak
The gold standard for assessing cardiovascular fitness is exercise capacity as determined from peak volume of oxygen consumption (VO2peak) and treadmill time during a graded exercise test. A physician supervised, individualized ramp treadmill protocol will be performed on each participant. In this protocol, participants walk at a brisk pace with the speed based on their comfort and fitness. For lower fit individuals, the grade will be increased at a rate of 1%/minute, and for higher fit individuals, the grade will be increased at a rate of 2%/minute. The treadmill test will be performed according to guidelines set by the American College of Sports Medicine (ACSM, 2014), to evaluate the subject's cardiovascular response to exercise.
Time frame: 6 weeks (Post exercise training)