Boulé, N. G. et al. Effects of exercise training on glucose homeostasis: the HERITAGE Family Study. Diabetes Care 28, 108-114
ABSTRACT 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.
- SourceAvailable from: Gerardo Garcia-Rivas
[Show abstract] [Hide abstract]
- "Exercise has beneficial effects in glucose homeostasis improving insulin sensitivity in healthy and diabetic persons   . Exercise improves SR Ca 2+ handling by SERCA in skeletal muscle . "
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 pancreasCell calcium 09/2014; DOI:10.1016/j.ceca.2014.09.005 · 3.51 Impact Factor
[Show abstract] [Hide abstract]
- "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. "
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
[Show abstract] [Hide abstract]
- "For example, two ‘inactive’ people identified according to low participation in physical activity above 3 METs in bouts of 10 min could have highly divergent physical activity energy expenditure (i.e., PAL); and thus might not be expected to respond in the same way to a given intervention. Whether this plays a part in explaining some of the individual variability in physiological and health-related outcomes that has been documented in response to training studies is an open question . "
ABSTRACT: Recently, there has been some discussion of whether it is possible to score highly in one dimension of physical activity behaviour (e.g., moderate intensity exercise) whilst also scoring poorly in another (e.g., sedentary time). Interestingly, direct empirical observations to support these proposals are lacking. New technologies now enable the capture of physical activity thermogenesis on a minute-by-minute basis and over a sustained period. We used one of the best available technologies to explore whether individuals can score differently in various physiologically-important physical activity dimensions. We determined minute-by-minute physical activity energy expenditure over 7 days in 100 men aged 28±9 years. We used combined accelerometry and heart rate with branched equation modelling to estimate energy expenditure and extracted data for key physical activity outcomes and descriptors. Although some physical activity outcomes were tightly correlated, the attainment of one threshold for a given physical activity dimension did not automatically predict how well an individual scored in another dimension (with bivariate correlations ranging from 0.05 to 0.96). In one illustrative example of this heterogeneity, although 41 men showed a relatively low Physical Activity Level (total energy expenditure/resting energy expenditure ≤1.75), only 17% (n = 7) of these men showed consistently low physical activity across other dimensions (moderate intensity activity, vigorous intensity activity, and sedentary time). Thus, physical activity is highly heterogeneous and there is no single outcome measure that captures all the relevant information about a given individual. We propose that future studies need to capture (rather than ignore) the different physiologically-important dimensions of physical activity via generation of integrated, multidimensional physical activity 'profiles'.PLoS ONE 02/2013; 8(2):e56427. DOI:10.1371/journal.pone.0056427 · 3.23 Impact Factor