Effect of Combined Aerobic and Resistance Training and Detraining on Insulin Sensitivity (Si) in a Sedentary, Overweight, Non Diabetic Population from STRRIDE-AT/RT (Studies of a Targeted Risk Reduction Intervention Through Defined Exercise)

Presentation Number: MON-842
Date of Presentation: June 17th, 2013

Hiba Abou Assi*1, Cris A Slentz1, Lucy W Piner1, Leslie Willis1, Lori Bateman1, Charles Tanner2, Connie Bales1, Joseph A Houmard3, Erik Kraus1 and William E Kraus1
1Duke University Medical Center, 2East Carolina University, 3East Carolina University, Greenville, NC

Abstract

Both aerobic (AT) and resistance training (RT) are recommended exercise prescriptions, mainly based on evaluating each modality separately.  The purpose of this study, was to compare the effects of AT, RT and the combination (AT/RT) on Si measured using intravenous glucose tolerance test (IVGTT) both pre-post training (PT) (within 24 hours after the last bout of exercise), and after 14 days of detraining (DT). We hypothesized that responses PT might be due at least in part to responses to the last bout of exercise, but that those sustained  after 14 days of DT would be due to persistent effects due to the training stimulus. Methodology: After a 4-month run-in period, participants were randomized into one of 3 8-month exercise training programs: (1)RT (n=29); (2)AT (n=39); (3) Combination of AT/RT (n=25). Si was calculated using Bergman’s minimal model in a population of overweight sedentary middle aged men and women. Results: There were no significant differences in the baseline Si, age, BMI, gender or race distribution among the 3 groups. Mean Si change for the groups was +3.12, -0.23, and -0.49 mU/L*min for AT/RT, AT and RT respectively.  PT the change in Si in the AT/RT group was significantly greater than AT alone (p=0.006) and RT alone (p=0.001).  More than half (58%) of the Si change for AT/RT (1.84 mU/L*min) persisted after 14 days of DT.  To explore possible mechanisms responsible for the observed effects, multivariable modeling was performed using linear models with backward stepwise variable selection.  We included variables describing change in cardiorespiratory fitness (VO2), regional adiposity (liver fat, thigh muscle adipose tissue, subcutaneous adipose tissue, visceral adipose tissue (VAT), alanine amino transferase,  waist circumference) and general body composition (lean body mass, fat mass, BMI). None of these variables could explain the PT effect of AT/RT on Si. Change in VAT approached statistical significance (p=0.07).  For the DT effect, the final regression model included VAT, fat mass and lean body mass (R2=0.32, p=0.007). Conclusions: We made 2 major and unexpected observations. 1) The combined AT/RT program had a synergistic effect (more than additive effects of the components alone) on Si with a significant improvement acutely PT, probably due to skeletal muscle adaptations. 2) More than half of the effect persisted after 14 days of DT in this group, probably secondary to body composition adaptations durable for at least 14 days

 

Nothing to Disclose: HA, CAS, LWP, LW, LB, CT, CB, JAH, EK, WEK