Our purpose was to investigate the effects of low-volume, high-intensity interval training (HIT) on cardiometabolic risk and exercise capacity in women with type 2 diabetes mellitus (T2DM). Sedentary overweight/obese T2DM women (age=44.5±1.8 years; BMI=30.5±0.6 kg/m(2)) were randomly assigned to a tri-weekly running-based HIT program (n=13) or non-exercise control follow-up (CON; n=10). Glycemic control, lipid and blood pressure levels, endurance performance, and anthropometry were measured before and after the follow-up (16 weeks) in both groups. Medication intake was also assessed throughout the follow-up. Improvements (P<0.05) on fasting glucose (14.3±1.4%), HbA1c (12.8±1.1%), systolic blood pressure (3.7±0.5 mmHg), HDL-cholesterol (21.1±2.8%), triglycerides (17.7±2.8%), endurance performance (9.8±1.0%), body weight (2.2±0.3%), BMI (2.1±0.3%), waist circumference (4.0±0.5%) and subcutaneous fat (18.6±1.4%) were found after HIT intervention. Patients of HIT group also showed reductions in daily dosage of antihyperglycemic and antihypertensive medication during follow-up. No changes were found in any variable of CON group. The HIT-induced improvements occurred with a weekly time commitment 56-25% lower than the minimal recommended in current guidelines. These findings suggest that low-volume HIT may be a time-efficient intervention to treat T2DM women.

The glucose transporter GLUT4 is critical for skeletal muscle glucose uptake in response to insulin and muscle contraction/exercise. Exercise increases GLUT4 translocation to the sarcolemma and t-tubule and, over the longer term, total GLUT4 protein content. Here, we review key aspects of GLUT4 biology in relation to exercise, with a focus on exercise-induced GLUT4 translocation, postexercise metabolism and muscle insulin sensitivity, and exercise effects on GLUT4 expression.

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BackgroundGlycogen is a branched polysaccharide of glucose residues, consisting of α-1-4 glycosidic linkages with α-1-6 branches that together form multi-layered particles ranging in size from 30 nm to 300 nm. Glycogen spatial conformation and intracellular organization are highly regulated processes. Glycogen particles interact with their metabolizing enzymes and are associated with a variety of proteins that intervene in its biology, controlling its structure, particle size and sub-cellular distribution. The function of glycogen in adipose tissue is not well understood but appears to have a pivotal role as a regulatory mechanism informing the cells on substrate availability for triacylglycerol synthesis. To provide new molecular insights into the role of adipocyte glycogen we analyzed the glycogen-associated proteome from differentiated 3T3-L1-adipocytes.ResultsGlycogen particles from 3T3-L1-adipocytes were purified using a series of centrifugation steps followed by specific elution of glycogen bound proteins using α-1,4 glucose oligosaccharides, or maltodextrins, and tandem mass spectrometry. We identified regulatory proteins, 14-3-3 proteins, RACK1 and protein phosphatase 1 glycogen targeting subunit 3D. Evidence was also obtained for a regulated subcellular distribution of the glycogen particle: metabolic and mitochondrial proteins were abundant. Unlike the recently analyzed hepatic glycogen proteome, no endoplasmic proteins were detected, along with the recently described starch-binding domain protein 1. Other regulatory proteins which have previously been described as glycogen-associated proteins were not detected, including laforin, the AMPK beta-subunit and protein targeting to glycogen (PTG).ConclusionsThese data provide new molecular insights into the regulation of glycogen-bound proteins that are associated with the maintenance, organization and localization of the adipocyte glycogen particle.

Objective The purpose of this study was to evaluate the effect of exercise training on ectopic fat within skeletal muscle (intermuscular adipose tissue [IMAT]) in adult populations with chronic diseases. Methods A literature search was conducted in relevant databases to identify randomized controlled trials (RCTs) from inception. Selected studies examined the effect of aerobic training (AET), resistance training (RT), or combined training (COM) on IMAT as assessed by noninvasive magnetic resonance (MRI) or computed tomography (CT). Eligibility was determined using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Data extraction was performed using the population (P), intervention (I), comparison (C), outcome (O), timing (T), and settings (S) approach. Methodological quality was analyzed by the Cochrane risk of bias assessment. Standardized effect sizes (ES) with 95% Cis were calculated. Heterogeneity among studies was quantified using I2 statistics. Subgroup and meta-regression analyses were included. Risk of publication bias was examined by the Egger regression test. Results Nineteen RCTs included 962 adults (628 women; age range = 34.8–93.4 y) with different chronic conditions that participated in 10 AET, 12 RT, and 5 COM interventions. The quality of studies was deemed moderate. Overall, the effect of exercise on IMAT was small (ES = 0.24; 95% CI = 0.10–0.37; heterogeneity I2 = 0.0%) compared with no exercise or control interventions. Moderate intensity AET and COM had larger ES compared with RT regardless of intensity. This effect was associated with exercise-induced body weight and fat mass losses. Subgroup analysis revealed larger ES in studies assessing IMAT by MRI compared with CT, in adults and middle-aged individuals compared with older adults, and in participants who were HIV+ compared with other diagnoses. Conclusion AET and COM of moderate intensity reduce IMAT in individuals from 18 to 65 years of age who are affected by chronic diseases. This effect is associated with exercise-induced body weight and fat mass losses. In older individuals who are frail and patients at an advanced disease stage, exercise may result in a paradoxical IMAT accumulation. Impact In people affected by chronic conditions, IMAT accumulation induces muscle mass and strength losses, decline in physical performance, inflammation, and metabolic alterations. The present study shows that moderate intensity AET or COM prevent or reduce IMAT in these conditions. Thus, the deleterious effect of IMAT on skeletal muscle homeostasis may be reverted by a properly prescribed exercise regime. Findings of the present systematic review are critical for physical therapists and health care professionals as they emphasize the therapeutic role of exercise and provide recommendations for exercise prescription that ultimately may have a positive impact on the course of disease, recovery of functionality, and independence. Lay summary Aerobic exercise (eg, walking/jogging, cycling) alone or combined with resistance exercise (strength training with free-weights, kettle bells, or gym equipment) is effective in reducing fat streaks that infiltrate muscles and impair muscle function and growth, particularly in adults affected by chronic diseases.