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Exercise is Medicine: Translational Research in Obesity and Insulin Resistance Alice S. Ryan, Ph.D. Baltimore VA Medical Center University of MD School of Medicine
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“basic muscle- strengthening activities twice a week … and find two and a half more hours in your week for moderate aerobic activity.” – Science of Healthy Living Advice from Newsweek 2010
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Percentage of Adults Who Reported No Leisure-Time Physical Activity by Age in Maryland, 2001-2003
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Data from CDC National Center for Chronic Disease Prevention & Health Promotion Behavioral Risk Factor Surveillance System % BMI>3028% % BMI>25 40% 31% 12%
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BMI (kg/m 2 ) <22 22-25 26-30 31-35 >35 <22 22-25 26-3031-35 >35 Percent Diabetic Age (years) 20 - 54 60 - 74 Prevalence of Diabetes by Age and Obesity
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Abdominal Fat Mid-thigh is the Fat? Where is the Fat?
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Visceral and Subcutaneous Adipose Depots Fat Distribution Trends in Postmenopausal Women Sample: Caucasian N = 50 – 80 per group Total and Central Obesity
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Increased Fasting Glucose & Insulin across VAT quintiles VAT quintiles (cm 2 ) 11 1,2, 3 1 Numbers signify P<0.05 from quintiles 1, 2, 3 Analyses adjusted for age, fat mass, & race 1 1,2,3 Nicklas et al. Diabetes Care, 2003
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VAT of ~ 100-110 cm 2 is predictive of adverse lipid (HDL, TG) and diabetes risk factors in women. Depres and Lamarche, Nutr Res Rev, 1993 Williams MJ et al, Int J Obes Relat Metab Disord, 1996 Nicklas et al., Diabetes Care, 2003 Visceral Adipose Tissue Risk
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Exercise Reduces Visceral Fat in Women Athletes N = 10 – 14 per group Ryan et al. Am J of Physiol, 1996 P < 0.01 VAT (cm 2 )
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Visceral Adipose Tissue Decreases with ↑VO 2 max r=-0.47, p<0.01 Lynch et al., J Appl Physiol, 2001
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Insulin 80mU/min BEDSIDE Measurement of Insulin Sensitivity: Hyperinsulinemic-euglycemic clamp
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Chronic Exercise in Older Women Prevents the Decline in Insulin Sensitivity Observed with Aging Ryan et al. J Appl Physiol, 2001 Glucose Uptake (umol/kg FFM /min ) (umol/kg FFM /min ) *P < 0.05. 0 10 20 30 40 50 60 70 ControlsAthletes 18-29 30-39 40-49 50-69 18-29 40-50 *
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Older Elite Football Players have Reduced Cardiac Risk Factors Former Colts compared to age, BMI, race and current physical activity level matched men: 26% lower visceral fat and lower total body fat (p<0.01). 13% higher muscle mass (p<0.01) 37% higher HDL-C & 31% lower TG (p<0.05) Suggests that the high levels of exercise in young adulthood conferred benefits later in life Lynch et al. Med Sci Sports Exerc, 2007
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Can We Modify Obesity and Insulin Resistance with Exercise Training?
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Dietary Stabilization 0 m 6 m 12 m Study Design Interventions WL: 1x/wk AEX+WL: 3x/wk Weight Stable 2 wks Metabolic Testing Screening Enrollment 45 - 80 year old Caucasian or African American women Postmenopausal (1 year) BMI: 25 – 50 kg/m2 Sedentary, Weight stable Non-smokers (≥ 1 year) No symptomatic heart disease or medications interfering with muscle metabolism
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0 m 6 m 12 m Study Design Interventions Metabolic Testing VO 2 max, Body Composition (DXA, CT) 3-hr OGTT 3 hr 80 mU/m 2 /min Hyperinsulinemic- euglycemic Clamp w/Indirect Calorimetry Skeletal Muscle Biopsy (basal & @120min) Gluteal & Abdominal Adipose Tissue Biopsy Metabolic Testing
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Study Design Screening N ~ 3000 Enrollment N = 292 AEX+WL N = 88 Entered WL N = 86 Entered Metabolic Testing N = 174 AEX+WL N = 53 Completed WL N = 50 Completed Dropped N = 63 Completed & Noncompliant N=8
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WeightVO 2 max * * * (kg) (l/min) Successful Weight Loss with AEX+WL and WL Improvements in Fitness only with AEX+WL *P<0.001 14% 8% ‡P<0.05 AEX+WL vs. WL ‡
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Fat MassFFM (kg) Losses of both Fat Mass and FFM with AEX+WL and WL 16% 13% * * 2% 4% * P<0.001 ‡P<0.05 ‡ ‡
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Visceral Fat Area Mid-thigh Intramyocellular Lipid Reductions in Abdominal and Intra-muscular Fat (cm 2 ) 16% 13% 9% *P<0.001 * * + +
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Improvements in Insulin Sensitivity Glucose Uptake ( mol/kg FFM /min) 14% 6% * * P<0.01 ‡P<0.05
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Improvements in Insulin Sensitivity are associated with an Increase in Fitness ∆ VO 2 max (l/min) ∆ M (µmol/kg FFM /min) r=0.30,P<0.05
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Mechanisms of Action of Lifestyle Interventions Muscle Adipose Insulin Sensitivity Capillarization Insulin Activation of Glycogen Synthase ↑ Enzymes of Fatty Acid Metabolism Inflammation Fat stores Exercise Training Weight Loss
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“BEDSIDE TO BENCH” Skeletal Muscle and Adipose Tissue of Exercise Mechanisms of Exercise Gluteal Adipose Tissue BiopsyVastus Lateralis Biopsy
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Skeletal Muscle Capillarization and Fiber Type Double Stain Myosin ATPase CD: Capillary Density (cap/mm 2 ) CFPE: Capillary-to-fiber perimeter exchange index (cap/mm perimeter) Type I: stain dark brown/black Type IIa: stain light brown/white Type IIx: stain brown
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VASCULAR and SYSTEMIC MARKERS in NGT (n = 42) and IGT (n = 28) Postmenopausal Women * a P =0.06, * P<0.01, † P<0.005 IGT women were older, had a higher BMI, and a lower M than NGT. † a VASCULAR and SYSTEMIC MARKERS in NGT (n = 42) and IGT (n = 28) Postmenopausal Women * a P =0.06, * P<0.01, † P<0.005 IGT women were older, had a higher BMI, and a lower M than NGT. † a VASCULAR and SYSTEMIC MARKERS in NGT (n = 42) and IGT (n = 28) Postmenopausal Women * a P =0.06, * P<0.01, † P<0.005 IGT women were older, had a higher BMI, and a lower M than NGT. † a Reduced Skeletal Muscle Capillarization is Associated with Glucose Intolerance Prior et al. Microcirculation, 2009
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Insulin Sensitivity is Reduced In Women with Impaired Glucose Tolerance Glucose Uptake ( mol/kg FFM /min) * * P<0.01 n = 64 n = 34
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0.7 0.8 0.9 1 FastingInsulin-Stimulated MetabolicInflexibility inObeseSubjects lean obese Kelly & Mandarino, Diabetes 2000 Metabolic Inflexibility Ability to switch from fat utilization during fasting to carbohydrate utilization during hyperinsulinemia (Kelley et al. 2000) Clamp RQ – Fasting RQ
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Metabolic Flexibility is Associated with Insulin Sensitivity in Postmenopausal Women n = 92, r=0.46, P<0.0001
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=-3%, P=NS =49%, P<0.05 P<0.01 Exercise + Weight Loss Increases Muscle LPL WL AEX+WL Pre Post Skeletal Muscle Lipoprotein Lipase
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Pre Post =-6%, P=NS =45%, P<0.05 P<0.05 Muscle Acyl-CoA Synthase Exercise + Weight Loss Increases Skeletal Muscle ACS
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=-1%, p=NS =32%, P=0.05 P<0.08 Muscle Citrate Synthase Pre Post Exercise + Weight Loss Increases Skeletal Muscle CS
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=-18%, P=0.01 =-26%, P<0.001 =-14%, P=NS =-28%, P<0.001 Exercise + Weight Loss Decreases Adipose Tissue LPL Gluteal Lipoprotein LipaseAbdominal Lipoprotein Lipase Pre Post
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=54%, p=NS =-32%, P=0.005 P<0.05 Exercise + Weight Loss Shifts Lipid Partitioning from Storage to Oxidation Ratio of Abdominal to SM-LPL Pre Post Ratio of Gluteal to SM-LPL =-24%, p<0.05 Pre Post P<0.09
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Insulin Suppresses ACS after Exercise Training Change in insulin’s effect on ACS after AEX+WL in postmenopausal women (n = 17, *P<0.05). *
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Insulin Suppresses -HAD after Exercise Training Change in insulin’s effect on -HAD after AEX+WL in postmenopausal women (n = 17, *P<0.05). *
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“Bench to Bedside” How is this Translated to an Exercise Prescription?
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Summary of the ACSM/AHA Updated Physical Activity Guidelines for Healthy Adults Under Age 65 Do moderate-intensity cardiovascular activity for 30 minutes a day, 5 days a week or Do vigorous cardiovascular activity 20 minutes a day, 3 days a week and Do 8 – 10 resistance-training exercises, performing 8 – 12 repetitions for each exercise, twice a week Moderate-intensity physical activity means working hard enough to raise your heart rate and break a sweat, yet still being able to carry on a conversation. It should be noted that to lose weight or maintain weight loss, 60 to 90 minutes of physical activity may be necessary. The 30- minute recommendation is for the average healthy adult to maintain health and reduce the risk for chronic disease. Med Sci Sports Exercise: 39(8); 1423-1434, 2007
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Benefits of Aerobic Exercise Improved cardio-respiratory fitness Weight Control Improved Endurance Stress Relief Improved energy Decreased fatigue Improved immune system Improved quality of sleep Psychological benefits
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Physical Activity Pyramid Leisure Time Activity Cardiovascular Exercise Strength TrainingFlexibility Inactivity in moderation
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Acknowledgements Many Thanks! Investigators: Andrew Goldberg, M.D. Heidi Ortmeyer, Ph.D. Jacob Blumenthal, M.D. Lyndon Joseph, Ph.D. Susan Fried, Ph.D. John McLenithan, Ph.D. Steve Prior, Ph.D. Clinical Staff: Joyce Evans, R.N. Sarah Witten, R.N. Kathie Brandt, R.N. Ivey Dorsey, R.N. Anita Neal, L.P.N. Cheryl Beasley, L.P.N. Luz Ortiz-Corral, R.N. Lynn Stars-Zorn, N.P. Linda Hatler, N.P. Peter Normandt, N.P. Dieticians: Kelly Ort, R.D. Kathy Simpson, R.D. Andriane Kozlovsky, R.D Amy Matson, R.D. Tara Caulder, R.D. Exercise Physiologists: Lynda Robey, M.S. Gretchen Zietowski, M.S., R.N. Greig Frietag, M.S. Nicole Fendrick, M.S.. Melinda Erbe, M.S. Research Assistants: Melissa Gray Keisha Galloway, M.S. Agnes Kohler, M.S. Carole St. Clair Sara Herts Jonelle George Linsday Koepper Urmila Sreenivasan Tara McDonald Lisa McFarland Sumi Khan Nikki Glynn Funding: VA NIH
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