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Short-term removal of exercise impairs glycemic control in older adults: A randomized trial.
Reynolds, LJ, Williams, TM, Harden, JE, Twiddy, HM, Kearney, ML
Physiological reports. 2023;11(2):e15591
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Advancements in glucose monitoring make assessing free-living postprandial blood glucose levels convenient and feasible. Continuous glucose monitoring systems assess blood glucose levels 24h a day and have been demonstrated to enhance diabetes management. Both acutely and chronically, physical activity and/or exercise is a powerful modulator of glycaemic control. The aim of this study was to examine if the alterations in glycaemic control in older adults who exercise were different compared to young adults who exercise, in response to short-term removal of exercise. This study was a randomised, cross-over, exploratory study design which included 20 participants (9 young, active participants and 11 older, active participants). Participants had glycaemic control assessed for 3 days while performing their normal habitual exercise and for 3 days while refraining from habitual exercise. Results show that three days of exercise removal impairs glycaemic control in older adults as well as young adults. In fact, older adults (even though they have worse glycaemic control than younger adults) do not experience a greater impairment in glycaemic control compared to young adults. Authors conclude that their findings support the overall need for regular, daily exercise in adults, particularly older adults, who have a worse glycaemic profile.
Abstract
Postprandial glycemia (PPG) predicts cardiovascular disease, and short-term physical inactivity increases PPG in young, active adults. Whether this occurs in older, active adults who may be more prone to bouts of inactivity is unknown. This study determined if postprandial interstitial glucose (PPIG) was impaired in active older adults following the removal of exercise for 3 days (NOEX) compared to active young adults. In this randomized, crossover study, 11 older (69.1 ± 1.9 years) and 9 young (32.8 ± 1.8 years) habitually active (≥90 min/week of exercise) adults completed 3-days of NOEX and 3-days of normal habitual exercise (EX), separated by ≥1 week. Diet was standardized across phases. Glycemic control (3-day average) was assessed via continuous glucose monitoring during both phases. Significant main effects of age and phase were detected (p < 0.05), but no interaction was found for steps/day (p > 0.05) (old EX: 6283 ± 607, old NOEX 2380 ± 382 and young EX: 8798 ± 623, young NOEX 4075 ± 516 steps/day). Significant main effects of age (p = 0.002) and time (p < 0.001) existed for 1-h PPIG, but no effect of phase or interactions was found (p > 0.05). Significant main effects (p < 0.05) of age (old: 114 ± 1 mg/dl, young: 106 ± 1 mg/dl), phase (NOEX: 112 ± 1 mg/dl, EX: 108 ± 1 mg/dl), and time (0 min: 100 ± 2, 30 min: 118 ± 2, 60 min: 116 ± 2, 90 min: 111 ± 2, 120 min: 108 ± 2 mg/dl) in 2-h PPIG were detected, but no interaction was found (p > 0.05). However, only significant main effects of phase (NOEX: 14 ± 1 and EX:12 ± 1, p > 0.05) were found for 24-h blood glucose standard deviation. Older adults appear to have impaired glycemic control compared to young adults and exercise removal impairs glycemic control in both populations. Yet, the impairment in glycemic control with exercise removal is not different between old and young adults.
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The Influence of Whey Protein on Muscle Strength, Glycemic Control and Functional Tasks in Older Adults with Type 2 Diabetes Mellitus in a Resistance Exercise Program: Randomized and Triple Blind Clinical Trial.
Soares, ALS, Machado-Lima, A, Brech, GC, Greve, JMD, Dos Santos, JR, Inojossa, TR, Rogero, MM, Salles, JEN, Santarem-Sobrinho, JM, Davis, CL, et al
International journal of environmental research and public health. 2023;20(10)
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Type 2 Diabetes Mellitus (T2DM) is a common metabolic disease and the prevalence of T2DM is increasing among older adults. Resistance training is known to be an effective therapeutic strategy as it can positively influence the mechanisms of T2DM pathophysiology. Previous research suggests that whey protein supplementation can positively influence the different mechanisms of T2DM pathophysiology and improve muscle mass and glycaemic control. This triple-blinded, randomised controlled parallel-arm trial included twenty-eight male older adults to assess the effect of whey protein supplementation combined with resistance training for twelve weeks on glycaemic control, functional tasks, muscle strength, and body composition. The control group was supplemented with maltodextrin. All participants followed resistance training and were given nutritional guidance. Twelve weeks of resistance training improved muscle strength significantly. However, 20g whey protein supplementation did not improve performance in functional tasks, glycaemic control, or body composition in the test group of older adults with T2DM. Whey protein supplementation showed no significant synergetic effects when combined with resistance training in the test group. Due to the heterogeneity of the present study, further robust studies are warranted to investigate the effects of whey protein supplementation and resistance training. However, healthcare professionals can use the results of this study to understand the effect of resistance training alone and the safety profile of whey protein supplementation in older adults with T2DM.
Abstract
OBJECTIVES To evaluate the effect of whey protein (WP) supplementation associated with resistance training (RT) on glycemic control, functional tasks, muscle strength, and body composition in older adults living with type 2 diabetes mellitus (T2DM). Secondly, to evaluate the safety of the protocol for renal function. METHODS The population comprised twenty-six older men living with T2DM (68.5 ± 11.5 years old). The participants were randomly assigned to the Protein Group (PG) and the Control Group (CG). The handgrip test and evolution of exercise loads, according to the Omni Resistance Exercise Scale, evaluated muscle strength. Functional tasks were assessed by force platform in three different protocols: Sit-to-Stand, Step/Quick Turn, and Step Up/Over. Body composition was evaluated by bioimpedance and glycemic control and renal function were assessed by biochemical analyses. Both groups performed RT for 12 weeks, twice a week, prioritizing large muscle groups. Protein supplementation was 20 g of whey protein isolate and the CG was supplemented with an isocaloric drink, containing 20 g of maltodextrin. RESULTS There was a significant difference in muscle strength, according to the evolution of the exercise loads, but it was not confirmed in the handgrip test. However, there was no significant difference between the groups, regarding performance in functional tasks, glycemic control, or body composition. Renal function showed no alteration. CONCLUSION The intake of 20 g of WP in older male adults living with T2DM did not increase the effect of RT on muscle strength, functional tasks, and glycemic control. The intervention was proven safe regarding renal function.
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Effects of exercise intensity on gut microbiome composition and function in people with type 2 diabetes.
Torquati, L, Gajanand, T, Cox, ER, Willis, CRG, Zaugg, J, Keating, SE, Coombes, JS
European journal of sport science. 2023;23(4):530-541
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While it is well known that gut microbiome composition is both inherited and mostly modulated by diet, emerging evidence suggests regular exercise is associated with higher microbial diversity and health promoting taxa. The aim of this study was to examine whether different intensities of exercise exert differential effects on gut microbiome composition and function in low-active people with type 2 diabetes (T2D). This study was a sub-study of the Exercise for Type 2Diabetes (E4D) Study. Fourteen participants volunteered for this sub-study and were randomised into one of the two exercise groups. Results showed that: - in low active people with T2D, moderate intensity, longer duration exercise resulted in increased Bifidobacterium and Escherichia genera, A. municiphila, and butyrate-producing taxa from orders Lachnospirales and Clostridium Cluster IV. - higher intensity exercise also increased butyrate producers, but from different orders (Eryspelothrichales and Oscillospirales), and less investigated species (M.smithii, Negativibacilli spp). - there were no changes in gut microbiome metabolites (short-chain fatty acids). Authors concluded that over an 8-week training intervention, exercise intensity had differing effects on the abundance of specific gut microbiome taxa and function in low active people with T2D.
Abstract
Exercise is positively associated with higher microbial diversity, but there is limited information on exercise intensity's effect on gut microbiome composition and function in clinical populations. This study examines whether different intensities of exercise exert differential effects on gut microbiome composition and function in low active people with type 2 diabetes. This is a sub-study of the Exercise for Type 2 Diabetes Study, a single centre, prospective, randomised controlled trial. Participants (n = 12) completed 8-weeks of combined aerobic and resistance moderate intensity continuous training (C-MICT) or combined aerobic and resistance high-intensity interval training (C-HIIT). Faecal samples were collected before and after intervention to measure gut microbiome composition and metabolic pathways (metagenome shotgun sequencing) and short-chain fatty acids. Post-exercise α-diversity was different between groups as was the relative abundance of specific taxa was (p < .05). Post-exercise relative abundance of Bifidobacterium, A. municiphila, and butyrate-producers Lachnospira eligens, Enterococcus spp., and Clostridium Cluster IV were higher at lower exercise intensity. Other butyrate-producers (from Eryspelothrichales and Oscillospirales), and methane producer Methanobrevibacter smithii were higher at higher exercise intensity. Pyruvate metabolism (ko00620),COG "Cell wall membrane envelope biogenesis" and "Unknown function" pathways were significantly different between groups and higher in C-MICT post-exercise. Differential abundance analysis on KO showed higher expression of Two-component system in C-HIIT. Transcription factors and "unknown metabolism" related pathways decreased in both groups. There were no significant between group changes in faecal short chain fatty acids. Exercise intensity had a distinct effect on gut microbiome abundance and metabolic function, without impacting short-chain fatty acid output.HighlightsEvidence of exercise effect on gut microbiome outcomes is limited to healthy and athletic populationsIn low active people with type 2 diabetes, different exercise intensities increased specific health promoting and butyrate producers species, and showed differentially abundant gut microbiome metabolic pathways.Further investigation is warranted, and if this supports the present findings, then specific exercise intensities may be promoted to target specific species and optimise gut health.
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Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial.
Brennan, AM, Standley, RA, Anthony, SJ, Grench, KE, Helbling, NL, DeLany, JP, Cornnell, HH, Yi, F, Stefanovic-Racic, M, Toledo, FGS, et al
The journals of gerontology. Series A, Biological sciences and medical sciences. 2022;77(5):1088-1097
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Aging is marked by increased risk for type 2 diabetes, reduced muscle mass and strength (ie, sarcopenia), decreased physical function and cardiorespiratory fitness, ectopic fat deposition, and insulin resistance all of which increase the risk for physical disability, morbidity, and mortality. These adverse health consequences associated with advanced age are exacerbated with obesity and physical inactivity. The aim of this study was to investigate the effects of weight loss with or without exercise on skeletal muscle insulin sensitivity, exclusively in obese older adults. This study is a 2-site, 6-month randomized controlled trial with a parallel group design. Eighty-six older (60–80 years of age), physically inactive men and women with obesity were randomised into one of the 3 treatments (1:1:1 allocation ratio): control (health education), calorie restriction-induced weight loss, and weight loss with exercise. Results suggest that weight loss via calorie restriction alone is insufficient to significantly improve skeletal muscle insulin sensitivity and requires the addition of exercise to incur benefit, which was also true for clinical measures of insulin resistance including haemoglobin A1C [a blood test that measures the average blood sugar levels over a period of 3 months] and fasting insulin. Authors conclude that regular exercise should be considered as a useful and manageable adjunct to traditional weight loss therapies for older adults with obesity to mitigate risk for chronic disease and maintain functional independence and quality of life.
Abstract
BACKGROUND Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults. METHODS Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test. RESULTS WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01). CONCLUSIONS Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.
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Time-restricted eating and exercise training improve HbA1c and body composition in women with overweight/obesity: A randomized controlled trial.
Haganes, KL, Silva, CP, Eyjólfsdóttir, SK, Steen, S, Grindberg, M, Lydersen, S, Hawley, JA, Moholdt, T
Cell metabolism. 2022;34(10):1457-1471.e4
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A healthy diet and regular physical activity are primary lifestyle strategies for the prevention and treatment of obesity and its associated conditions. However, poor adherence rates to these strategies limit their effectiveness. Time-restricted eating (TRE) is a popular dietary strategy that emphasises the timing of meals in alignment with diurnal circadian rhythms, permitting ad libitum energy intake during a restricted eating window (8–10 h between the first and last energy intake of the day). The aim of this study was to investigate the isolated and combined effects of TRE and high-intensity interval training (HIIT) on glycaemic control and cardiometabolic health outcomes in women with overweight/obesity. This study is a 7-week randomised controlled trial with four parallel groups: TRE (energy intake limited to a %10-h eating window every day), HIIT (three supervised treadmill exercise sessions per week), a combination (TREHIIT), and a control group (CON, no intervention). Participants (n=131) were randomly assigned to one of the four groups. . Results show that 7 weeks of TRE, HIIT, or a combination failed to improve glycaemic control in reproductive-aged women with overweight/obesity. However, the combination of TRE and HIIT significantly reduced glycated haemoglobin levels compared with CON and induced greater losses in body weight, fat mass, and visceral fat area compared with either intervention alone. Isolated TRE resulted in lower nocturnal glucose concentrations compared with CON. Authors conclude that combining TRE with HIIT can rapidly induce several health benefits and decrease metabolic disease risk in women with overweight/obesity. In fact, the high rates of compliance and adherence shown in their findings, highlight the potential of these diet-exercise (TRE and HIIT) protocols to be implemented in clinical practice for treatment and primary prevention of overweight/ obesity.
Abstract
Diet modification and exercise training are primary lifestyle strategies for obesity management, but poor adherence rates limit their effectiveness. Time-restricted eating (TRE) and high-intensity interval training (HIIT) improve cardiometabolic health in at-risk individuals, but whether these two interventions combined induce superior improvements in glycemic control than each individual intervention is not known. In this four-armed randomized controlled trial (ClinicalTrials.gov NCT04019860), we determined the isolated and combined effects of 7 weeks of TRE (≤10-h daily eating window, with ad libitum energy intake) and HIIT (three exercise sessions per week), compared with a non-intervention control group, on glycemic control and secondary cardiometabolic outcomes in 131 women (36.2 ± 6.2 years) with overweight/obesity. There were no statistically significant effects after isolated TRE, HIIT, or a combination (TREHIIT) on glucose area under the curve during an oral glucose tolerance test (the primary outcome) compared with the control group (TRE, -26.3 mmol/L; 95% confidence interval [CI], -82.3 to 29.7, p = 0.36; HIIT, -53.8 mmol/L; 95% CI, -109.2 to 1.6, p = 0.057; TREHIIT, -41.3 mmol/L; 95% CI, -96.4 to 13.8, p = 0.14). However, TREHIIT improved HbA1c and induced superior reductions in total and visceral fat mass compared with TRE and HIIT alone. High participant adherence rates suggest that TRE, HIIT, and a combination thereof may be realistic diet-exercise strategies for improving markers of metabolic health in women at risk of cardiometabolic disease.
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Effects of curcumin and/or coenzyme Q10 supplementation on metabolic control in subjects with metabolic syndrome: a randomized clinical trial.
Sangouni, AA, Taghdir, M, Mirahmadi, J, Sepandi, M, Parastouei, K
Nutrition journal. 2022;21(1):62
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Metabolic syndrome (MetS) is a cluster of metabolic disorders such as hyperlipidaemia, hypertension, hyperglycaemia, insulin resistance, and abdominal obesity. MetS is associated with cardiovascular disease (CVD), type 2 diabetes mellitus and non-alcoholic fatty liver disease. The aim of this study was to investigate the effects of curcumin and/or coenzyme Q10 supplementation on metabolic syndrome components in subjects with MetS. This study is a 2×2 factorial, randomised, double-blinded, placebo-controlled study which was conducted for 12 weeks. Eighty-eight subjects were randomly assigned into four groups. All subjects completed the trial. Results show that curcumin supplementation improves lipid profile, but it does not have any effect on body composition, hypertension and fasting plasma glucose. However, supplementation with coenzyme Q10 as well as curcumin plus coenzyme Q10 did not show any significant effects on lipid profile, body composition, hypertension and fasting plasma glucose. Authors conclude that curcumin supplementation (especially by its effects on dyslipidaemia) is more effective than coenzyme Q10 as well as the combination of curcumin and coenzyme Q10 in the management of MetS. However, curcumin, coenzyme Q10 and their combination have no effect on body composition, hypertension and glycaemic control.
Abstract
BACKGROUND Metabolic syndrome (MetS) as a cluster of conditions including hyperlipidemia, hypertension, hyperglycemia, insulin resistance, and abdominal obesity is linked to cardiovascular diseases and type 2 diabetes. Evidence suggested that intake of curcumin and coenzyme Q10 may have therapeutic effects in the management of MetS. AIMS We investigated the effects of curcumin and/or coenzyme Q10 supplementation on metabolic syndrome components including systolic blood pressure (SBP), diastolic blood pressure (DBP), waist circumference (WC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-c) and fasting plasma glucose (FPG) as primary outcomes, and total cholesterol (TC), low density lipoprotein-cholesterol (LDL-c) and body mass index (BMI) as secondary outcomes in subjects with MetS. METHODS In this 2 × 2 factorial, randomized, double-blinded, placebo-controlled study, 88 subjects with MetS were randomly assigned into four groups including curcumin plus placebo (CP), or coenzyme Q10 plus placebo (QP), or curcumin plus coenzyme Q10 (CQ), or double placebo (DP) for 12 weeks. RESULTS The CP group compared with the three other groups showed a significant reduction in HDL-c (P = 0.001), TG (P < 0.001), TC (P < 0.001), and LDL-c (P < 0.001). No significant differences were seen between the four groups in terms of SBP, DBP, FPG, WC, BMI and weight. CONCLUSION Curcumin improved dyslipidemia, but had no effect on body composition, hypertension and glycemic control. Furthermore, coenzyme Q10 as well as the combination of curcumin and coenzyme Q10 showed no therapeutic effects in subjects with MetS. The trial was registered on 09/21/2018 at the Iranian clinical trials website (IRCT20180201038585N2), URL: https://www.irct.ir/trial/32518 .
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Adherence to Mediterranean Diet and NAFLD in Patients with Metabolic Syndrome: The FLIPAN Study.
Montemayor, S, Mascaró, CM, Ugarriza, L, Casares, M, Llompart, I, Abete, I, Zulet, MÁ, Martínez, JA, Tur, JA, Bouzas, C
Nutrients. 2022;14(15)
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Non-alcoholic fatty liver disease (NAFLD) is characterised by fat deposition that is not linked to excessive alcohol intake. This condition is often linked to other health issues such as obesity, metabolic syndrome, type 2 diabetes and cardiovascular disease, and they share common diagnostic biomarkers. An unhealthy diet and lifestyle are also linked to the progression of NAFLD. Mediterranean diet is a predominantly plant-based diet that may have an association with lower risk and reduced severity of NAFLD. This multicentre, prospective, randomised controlled trial included one hundred and thirty-six NAFLD patients to analyse the effect of Mediterranean diet adherence on NAFLD in patients with metabolic syndrome. The NAFLD patients followed a personalised Mediterranean diet and physical activity interventions for six months. Individuals with greater adherence to the Mediterranean diet and physical activity interventions showed improvements in body mass index, body weight, waist circumference, blood pressure and intrahepatic fat content after six months of intervention. Healthcare professionals can use the results of this study to understand the benefits of adherence to the Mediterranean diet and physical activity interventions in reducing NAFLD severity and metabolic irregularities. However, due to the small sample size of this study, further robust studies are required to evaluate the benefits of different dietary strategies, the therapeutic value of different food items and the intervention duration required to achieve improvements in NAFLD and metabolic syndrome.
Abstract
Unhealthy diet is an important factor in the progression of non-alcoholic fatty liver disease (NAFLD). Previous studies showed the benefits of a Mediterranean diet (MedDiet) on Metabolic syndrome (MetS), type 2 diabetes mellitus (T2DM), and cardiovascular diseases, which usually have a pathophysiological relationship with NAFLD. To assess the effect of adherence to a MedDiet on NAFLD in MetS patients after lifestyle intervention, this multicentre (Mallorca and Navarra, Spain) prospective randomized trial, with personalized nutritional intervention based on a customized MedDiet, coupled with physical activity promotion was performed to prevent, and reverse NAFLD among patients with MetS. The current analysis included 138 patients aged 40 to 60 years old, Body Mass Index (BMI) 27-40 kg/m2, diagnosed with NAFLD using MRI, and MetS according to the International Diabetes Federation (IDF). A validated food frequency questionnaire was used to assess dietary intake. Adherence to Mediterranean diet by means of a 17-item validated questionnaire, anthropometrics, physical activity, blood pressure, blood biochemical parameters, and intrahepatic fat contents (IFC) were measured. The independent variable used was changes in MedDiet adherence, categorized in tertiles after 6 months follow-up. Subjects with high adherence to the MedDiet showed higher decreases in BMI, body weight, WC, SBP, DBP, and IFC. An association between improvement in adherence to the MedDiet and amelioration of IFC after 6-month follow-up was observed. High adherence to the MedDiet is associated with better status of MetS features, and better values of IFC.
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Lipids activate skeletal muscle mitochondrial fission and quality control networks to induce insulin resistance in humans.
Axelrod, CL, Fealy, CE, Erickson, ML, Davuluri, G, Fujioka, H, Dantas, WS, Huang, E, Pergola, K, Mey, JT, King, WT, et al
Metabolism: clinical and experimental. 2021;121:154803
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Insulin resistance is a key pathophysiological mechanism in the development and progression of type 2 diabetes. Abnormalities in lipid metabolism and ectopic lipid accumulation are known to directly contribute to the onset of insulin resistance. Authors hypothesised that lipid infusion would increase dynamin related protein 1 [a type of protein]-mediated mitochondrial fission in skeletal muscle independent of function and content, consequently reducing peripheral insulin sensitivity. The study included sedentary but otherwise healthy adults who were prospectively randomized to receive either lipid or saline infusion to isolate the direct contribution of fatty acids to skeletal muscle mitochondrial dynamics. Results show that mitochondrial fission and quality control networks are activated in response to lipid infusion which occurs independent of changes in mitochondrial content or capacity and contributes to the onset of insulin resistance in healthy humans. Authors conclude that treatments that limit lipid-induced activation of mitochondrial fission and/or quality control processes may have therapeutic value in the treatment of insulin resistance.
Abstract
BACKGROUND AND AIMS A diminution in skeletal muscle mitochondrial function due to ectopic lipid accumulation and excess nutrient intake is thought to contribute to insulin resistance and the development of type 2 diabetes. However, the functional integrity of mitochondria in insulin-resistant skeletal muscle remains highly controversial. METHODS 19 healthy adults (age:28.4 ± 1.7 years; BMI:22.7 ± 0.3 kg/m2) received an overnight intravenous infusion of lipid (20% Intralipid) or saline followed by a hyperinsulinemic-euglycemic clamp to assess insulin sensitivity using a randomized crossover design. Skeletal muscle biopsies were obtained after the overnight lipid infusion to evaluate activation of mitochondrial dynamics proteins, ex-vivo mitochondrial membrane potential, ex-vivo oxidative phosphorylation and electron transfer capacity, and mitochondrial ultrastructure. RESULTS Overnight lipid infusion increased dynamin related protein 1 (DRP1) phosphorylation at serine 616 and PTEN-induced kinase 1 (PINK1) expression (P = 0.003 and P = 0.008, respectively) in skeletal muscle while reducing mitochondrial membrane potential (P = 0.042). The lipid infusion also increased mitochondrial-associated lipid droplet formation (P = 0.011), the number of dilated cristae, and the presence of autophagic vesicles without altering mitochondrial number or respiratory capacity. Additionally, lipid infusion suppressed peripheral glucose disposal (P = 0.004) and hepatic insulin sensitivity (P = 0.014). CONCLUSIONS These findings indicate that activation of mitochondrial fission and quality control occur early in the onset of insulin resistance in human skeletal muscle. Targeting mitochondrial dynamics and quality control represents a promising new pharmacological approach for treating insulin resistance and type 2 diabetes. CLINICAL TRIAL REGISTRATION NCT02697201, ClinicalTrials.gov.
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A Single Bout of Premeal Resistance Exercise Improves Postprandial Glucose Metabolism in Obese Men with Prediabetes.
Bittel, AJ, Bittel, DC, Mittendorfer, B, Patterson, BW, Okunade, AL, Abumrad, NA, Reeds, DN, Cade, WT
Medicine and science in sports and exercise. 2021;53(4):694-703
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Prediabetes is a metabolic condition defined by elevated fasting (impaired fasting glucose) and/or postprandial (impaired glucose tolerance) plasma glucose. The aim of this study was to determine the effects of a single bout of resistance exercise on postprandial glucose metabolism following a mixed meal in obese, sedentary men with prediabetes. This study is a randomised, cross-over study design which enrolled ten participants. Participants were aged 39-62 years, obese, and demonstrated insulin resistance with compensatory increases in beta cell function. Results show that a single bout of resistance exercise performed 4.5 hours before a mixed meal (as opposed to an oral glucose tolerance test) reduced total postprandial glucose appearance, increased insulin sensitivity, and reduced the glycaemic response to a mixed meal. However, it did not have effect on glucose oxidation in obese men with prediabetes. Improvements in insulin sensitivity were complemented by reduced postprandial insulin concentration. Authors conclude that further investigation is needed to elucidate how resistance exercise affects exogenous (meal) vs endogenous postprandial glucose metabolism, and if additional bouts of exercise (i.e. training) produce superior outcomes for this population.
Abstract
INTRODUCTION Prediabetes is a major risk factor for type 2 diabetes and cardiovascular diseases. Although resistance exercise (RE) is recommended for individuals with prediabetes, the effects of RE on postprandial glucose metabolism in this population are poorly understood. Therefore, the purpose of this study was to elucidate how RE affects postprandial glucose kinetics, insulin sensitivity, beta cell function, and glucose oxidation during the subsequent meal in sedentary men with obesity and prediabetes. METHODS We studied 10 sedentary men with obesity (body mass index, 33 ± 3 kg·m-2) and prediabetes by using a randomized, cross-over study design. After an overnight fast, participants completed either a single bout of whole-body RE (seven exercises, 3 sets of 10-12 repetitions at 80% one-repetition maximum each) or an equivalent period of rest. Participants subsequently completed a mixed meal test in conjunction with an intravenous [6,6-2H2]glucose infusion to determine basal and postprandial glucose rate of appearance (Ra) and disappearance (Rd) from plasma, insulin sensitivity, and the insulinogenic index (a measure of beta cell function). Skeletal muscle biopsies were obtained 90 min postmeal to evaluate pyruvate-supported and maximal mitochondrial respiration. Whole-body carbohydrate oxidation was assessed using indirect calorimetry. RESULTS RE significantly reduced the postprandial rise in glucose Ra and plasma glucose concentration. Postprandial insulin sensitivity was significantly greater after RE, whereas postprandial plasma insulin concentration was significantly reduced. RE had no effect on the insulinogenic index, postprandial pyruvate respiration, or carbohydrate oxidation. CONCLUSION/INTERPRETATION A single bout of RE has beneficial effects on postprandial glucose metabolism in men with obesity and prediabetes by increasing postprandial insulin sensitivity, reducing the postprandial rise in glucose Ra, and reducing postprandial plasma insulin concentration.
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Effects of high-intensity interval and moderate-intensity continuous aerobic exercise on diabetic obese patients with nonalcoholic fatty liver disease: A comparative randomized controlled trial.
Abdelbasset, WK, Tantawy, SA, Kamel, DM, Alqahtani, BA, Elnegamy, TE, Soliman, GS, Ibrahim, AA
Medicine. 2020;99(10):e19471
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Non-alcoholic fatty liver disease (NAFLD) is a condition linked to obesity and is characterised by high amounts of fat in the liver. This can lead to a high rate of mortality, but it can be improved by diet and exercise. It is unclear as to the best form of exercise for the improvement of NAFLD. This randomised control trial aimed to assess the effects of high-intensity interval exercise (HII) versus moderate-intensity exercise on liver fat content in 47 diabetic obese patients with NAFLD over 8 weeks. The results showed that regardless of exercise treatment, both improved measures of NAFLD and there were no differences between the two groups. Interestingly blood sugar control was also improved with both exercise treatments. It was concluded that both exercise regimes improved contributors to NAFLD, with no differences between the two treatments. This study would be useful to health professionals when recommending exercise to diabetic obese patients especially those with NAFLD, giving them the option of HII or MIC to improve their condition.
Abstract
BACKGROUND Some studies assessed the effect of aerobic exercise on diabetic obese patients with hepatic disease, while very limited studies compared high-intensity interval (HII) versus moderate-intensity continuous (MIC) on diabetic obese patients with non-alcoholic fatty liver disease (NAFLD). OBJECTIVES This study was designed to assess the effects of HII versus MIC on intrahepatic triglycerides (IHTG) and visceral lipids in diabetic obese patients with NAFLD. DESIGN Randomized controlled trial. METHODS Forty-seven diabetic obese individuals with NAFLD were enrolled in this study. The individuals were randomly divided into 16 in HII group, 15 in MIC group, and 16 in the controls. HII group received HII exercise, MIC group received 8-week MIC exercise while the control group did not receive any exercise intervention. IHTG and visceral lipids were assessed pre- and post-intervention. RESULTS Baseline and clinical characteristics showed nonsignificant difference among the 3 groups (P > .05). Both HII and MIC groups showed a significant reduction in hepatic fat and visceral lipids (P < .05), while the controls showed nonsignificant difference (P > .05) after completing the study intervention. Postintervention analysis showed nonsignificant changes between the HII and MIC groups (P > .05). CONCLUSIONS Exercise training wither HII or MIC aerobic exercise reduces IHGT and visceral lipids in diabetic obese patients with NAFLD. No differences were observed between the effects of both exercise programs on diabetic obese patients with NAFLD.