Effects of exercise training on glucose homeostasis: The HERITAGE Family Study

Laval University, Quebec City, Quebec, Canada
Diabetes Care (Impact Factor: 8.42). 02/2005; 28(1):108-14. DOI: 10.2337/diacare.28.1.108
Source: PubMed


To determine the effect of a 20-week endurance training program in healthy, previously sedentary participants on measures derived from an intravenous glucose tolerance test (i.v.GTT).
An i.v.GTT was performed before and after a standardized training program in 316 women and 280 men (173 blacks and 423 whites). Participants exercised on cycle ergometers 3 days per week for 60 sessions. The exercise intensity was progressively increased from 55% VO2max for 30 min per session to 75% VO2max for 50 min per session.
Mean insulin sensitivity increased by 10% (P < 0.001) following the intervention, but the variability in the changes was high. Men had larger improvements than women (P = 0.02). Improvements in fasting insulin were transitory, disappearing 72 h after the last bout of exercise. There were also significant mean increases in the glucose disappearance index (3%, P = 0.02) and in glucose effectiveness (11%, P < 0.001), measures of glucose tolerance and of the capacity of glucose to mediate its own disposal, respectively. The acute insulin response to glucose, a measure of insulin secretion, increased by 7% in the quartile with the lowest baseline glucose tolerance and decreased by 14% in the quartile with the highest baseline glucose tolerance (P < 0.001). The glucose area below fasting levels during the i.v.GTT was reduced by 7% (P = 0.02).
Although the effects of structured regular exercise were highly variable, there were improvements in virtually all i.v.GTT-derived variables. In the absence of substantial weight loss, regular exercise is required for sustained improvements in glucose homeostasis.

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    • "The results of the HERITAGE study showed decreased fasting insulin and increased insulin sensitivity in African American men after 20 weeks of training [11]. However, the study did not contain a control group and these positive findings have not been replicated. "
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    ABSTRACT: Lack of regular physical activity at prescribed intensity levels is a modifiable risk factor for insulin resistance and the development of diabetes. African American men are at increased risk for developing diabetes and most African American men are not meeting the current recommended levels of physical activity. The primary objective of the Aerobic Plus Resistance Training and Insulin Resistance in African American Men (ARTIIS) study is to determine the effectiveness of an exercise training intervention aimed at reducing diabetes risk factors in African American men at risk for developing diabetes. Insufficiently active 35-70 year old African American men with a family history of diabetes were eligible for the study. The 5-month randomized controlled trial assigns 116 men to an exercise training or healthy living control arm. The exercise training arm combines aerobic and resistance training according to the current national physical activity recommendations and is conducted in community (YMCA) facilities. The healthy living arm receives information promoting healthy lifestyle changes. Insulin response to an oral glucose load is the primary outcome measure, and changes in physiological parameters, cardiorespiratory fitness, strength, body composition, and psychological well-being comprise the secondary outcomes. The ARTIIS study is one of the first adequately powered, rigorously designed studies to investigate the effects of an aerobic plus resistance exercise training program and to assess adherence to exercise training in community facilities, in African American men. Copyright © 2015. Published by Elsevier Inc.
    Contemporary clinical trials 05/2015; 43. DOI:10.1016/j.cct.2015.05.004 · 1.94 Impact Factor
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    • "Exercise has beneficial effects in glucose homeostasis improving insulin sensitivity in healthy and diabetic persons [44] [45] [46]. Exercise improves SR Ca 2+ handling by SERCA in skeletal muscle [47]. "
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    ABSTRACT: Cytosolic calcium concentration ([Ca2+]c) is fundamental for regulation of many cellular processes such metabolism, proliferation, muscle contraction, cell signaling and insulin secretion. In resting conditions, the sarco/endoplasmic reticulum (ER/SR) Ca2+ ATPase’s (SERCA) transport Ca2+ from the cytosol to the ER or SR lumen, maintaining the resting [Ca2+]c about 25-100 nM. A reduced activity/expression of SERCA2 protein has been described in heart failure and diabetic cardiomyopathy, resulting in an altered Ca2+ handling and cardiac contractility. In the diabetic pancreas, has been reported reduction in SERCA2b and SERCA3 expression in β-cells, resulting in diminished insulin secretion. Evidence obtained from different diabetes models have suggested a role for advanced glycation end products formation, oxidative stress and increased O-GlcNAcylation in the lowered SERCA2 expression observed in diabetic cardiomyopathy. However, the role of SERCA2 down-regulation in the pathophysiology of diabetes mellitus and diabetic cardiomyopathy is not yet well described. In this review, we make a comprehensive analysis of the current knowledge of the role of the SERCA pumps in the pathophysiology of insulin-dependent diabetes mellitus type 1 (TIDM) and type 2 (T2DM) in the heart and β-cells in the pancreas
    Cell calcium 09/2014; DOI:10.1016/j.ceca.2014.09.005 · 3.51 Impact Factor
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    • "The modest treatment effects are reflected by large between-subject variations in glucose tolerance with Δ2hPG ranging from -1.2 mM (i.e., positive responder, S7) to +3.2 mM (i.e., negative responder, S2) with three subjects (S1, S10 and S11) having non-significant changes (<± 0.4 mM, non-responder). Despite the small sample size and gender-specific cohort examined in this study, the disparity in treatment responses to HIIT as related to Δ2hPG is consistent with large-scale exercise interventions, where ≈ 30% of individuals are reported to have no measurable improvements in insulin sensitivity26, whereas ≈ 10% of subjects can have adverse outcomes in terms of risk factors for chronic diseases, including fasting insulin, triglycerides and/or HDL-cholesterol14. A MLR model comprising a panel of eight plasma metabolites was developed to predict changes in oral glucose tolerance (Δ2hPG), including key compounds associated with branched-chain/aromatic amino acids, urea cycle, thiol redox status and carnitine metabolism. "
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    ABSTRACT: High-intensity interval training (HIIT) offers a practical approach for enhancing cardiorespiratory fitness, however its role in improving glucose regulation among sedentary yet normoglycemic women remains unclear. Herein, multi-segment injection capillary electrophoresis-mass spectrometry is used as a high-throughput platform in metabolomics to assess dynamic responses of overweight/obese women (BMI > 25, n = 11) to standardized oral glucose tolerance tests (OGTTs) performed before and after a 6-week HIIT intervention. Various statistical methods were used to classify plasma metabolic signatures associated with post-prandial glucose and/or training status when using a repeated measures/cross-over study design. Branched-chain/aromatic amino acids and other intermediates of urea cycle and carnitine metabolism decreased over time in plasma after oral glucose loading. Adaptive exercise-induced changes to plasma thiol redox and orthinine status were measured for trained subjects while at rest in a fasting state. A multi-linear regression model was developed to predict changes in glucose tolerance based on a panel of plasma metabolites measured for naïve subjects in their untrained state. Since treatment outcomes to physical activity are variable between-subjects, prognostic markers offer a novel approach to screen for potential negative responders while designing lifestyle modifications that maximize the salutary benefits of exercise for diabetes prevention on an individual level.
    Scientific Reports 08/2014; 4:6166. DOI:10.1038/srep06166 · 5.58 Impact Factor
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