High intensity interval training improves liver and adipose tissue insulin sensitivity

Abstract

ObjectiveEndurance exercise training reduces insulin resistance, adipose tissue inflammation and non-alcoholic fatty liver disease (NAFLD), an effect often associated with modest weight loss. Recent studies have indicated that high-intensity interval training (HIIT) lowers blood glucose in individuals with type 2 diabetes independently of weight loss; however, the organs affected and mechanisms mediating the glucose lowering effects are not known. Intense exercise increases phosphorylation and inhibition of acetyl-CoA carboxylase (ACC) by AMP-activated protein kinase (AMPK) in muscle, adipose tissue and liver. AMPK and ACC are key enzymes regulating fatty acid metabolism, liver fat content, adipose tissue inflammation and insulin sensitivity but the importance of this pathway in regulating insulin sensitivity with HIIT is unknown.MethodsIn the current study, the effects of 6 weeks of HIIT were examined using obese mice with serine–alanine knock-in mutations on the AMPK phosphorylation sites of ACC1 and ACC2 (AccDKI) or wild-type (WT) controls.ResultsHIIT lowered blood glucose and increased exercise capacity, food intake, basal activity levels, carbohydrate oxidation and liver and adipose tissue insulin sensitivity in HFD-fed WT and AccDKI mice. These changes occurred independently of weight loss or reductions in adiposity, inflammation and liver lipid content.ConclusionsThese data indicate that HIIT lowers blood glucose levels by improving adipose and liver insulin sensitivity independently of changes in adiposity, adipose tissue inflammation, liver lipid content or AMPK phosphorylation of ACC.

Swimming training induces liver adaptations to oxidative stress and insulin sensitivity in rats submitted to high-fat diet

“…In these studies [31,32] PT began with the start of the diet for development of MS. Few studies [1,18] have evaluated PT as a treatment of already established MS. These studies show that PT induces a reduction in systolic blood pressure, together with increased sensitivity to insulin and in the gene expression of GLUT4 in white adipose tissue and gastrocnemius muscle [1], and reduces retroperitoneal and epididymal fat [18,33]. In our present study, PT should be considered a treatment because it started in the last 6 weeks of the diets, and therefore with an already established MS disorder, as shown through the increased MAP, HR and body mass of the rats.…”

High-intensity exercise training increases the diversity and metabolic capacity of the mouse distal gut microbiota during diet-induced obesity

“…2, D-F). We (38) recently demonstrated that this HIIT exercise protocol increased oxygen consumption (V O 2 ), carbon dioxide consumption (V CO 2 ), respiratory exchange ratio (RER), food intake, and water intake in HFD-fed mice. We also published that this HIIT exercise protocol does not alter body mass, whole body adiposity, adipose mass, liver mass, or heart mass (38).…”

“…After a 3-day acclimation to treadmill running (19), exercise capacity was measured using a graded exercise test during which mice began running at 8 m/min on a 5% grade and treadmill speed was gradually increased by 1 m/min every 2 min until exhaustion, as described previously (38,54). This test was also repeated after 6 wk of exercise training, which involved treadmill running 3 days per week for 1 h each day, as previously described (38). Specifically, the treadmill running involved running for 2 min at 17 m/min at a 5% grade (100% of average pretrained maximal running speed/exercise capacity) and then resting for 2 min.…”

“…Highintensity interval training (HIIT) has been shown to induce very similar metabolic effects to that elicited by endurance exercise training, including improvements in insulin sensitivity (25,36). The mechanisms by which HIIT improves insulin sensitivity are not well understood, since obesity status is usually not altered, and recent studies in HFD-fed mice have demonstrated that HIIT improves both adipose and liver insulin sensitivity without changing body mass or adiposity (38). Remarkably, these changes in liver and adipose tissue insulin sensitivity occurred independently of liver lipid content or adipose tissue inflammation, suggesting that other factors may have been responsible for the insulin-sensitizing effects of HIIT.…”

Iron, Hematological Parameters and Blood Plasma Lipid Profile in Vitamin D Supplemented and Non-Supplemented Young Soccer Players Subjected to High-Intensity Interval Training

“…Several studies have looked into the effect of intermittent training on total cholesterol, HDL-C, LDL-C, TG (30)(31)(32)(33)(34)(35)53) or VLDL, HDL and LDL lipoprotein particles (36). HIIT was shown to activate AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (MAPK), thereby increasing the capacity for glucose and fatty acid oxidation (54,55). The studies that examined the effect of intermittent training on plasma lipids or lipoproteins provided equivocal results, however; they differ largely with respect to training protocols (sprint, ergometer cycling, intensity, interval length from 8 s to 6 min, work : rest ratio), duration (from 8 wk to 18 mo), subjects investigated (usually sedentary individuals with comorbidities such as metabolic syndrome, obesity, essential hypertension), baseline lipid levels and work-to-rest ratio.…”