Skeletal muscle glycolytic and oxidative enzyme capacities are determinants of insulin sensitivity and muscle composition in obese women

Simoneau, J. A.; Colberg, Sheri R.; Thaete, F. Leland; Kelley, David E.

doi:10.1096/fasebj.9.2.7781930

Cited by 335 publications

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“…At rest, skeletal muscle is the primary site of insulin-stimulated glucose disposal 20 and there is increasing evidence that high muscle fat stores may play an important role in insulin resistance. 4,5,21,22 Conversely, when energy expenditure is considered, only about 28% of total energy expenditure can be accounted for by skeletal muscle. 23 Therefore, change in muscle fat oxidation at rest is likely to have a rather minor impact on whole body fat oxidation rate.…”

Section: Discussionmentioning

confidence: 99%

“…Second, CT results also suggest that women with a high muscle triglyceride content present a lower muscle citrate synthase activity (which is an index of muscle oxidative capacity) and insulin resistance. 5 On the other hand, an increase in intracellular muscle fat stores may facilitate the contact between intracellular fat stores and mitochondria and lead to an increase in fat oxidation rate. 6 In the present study, low attenuation muscle (LAM), assessed by CT, represents skeletal muscle enriched with diffuse fat stores, which are too small to be detected as distinct entities in a CT scan but important enough to reduce the attenuation of the muscle.…”

Section: Introductionmentioning

confidence: 99%

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Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

et al. 2001

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BACKGROUND: Muscle triacylglycerols (TG) are known to be a source of energy during submaximal exercise. OBJECTIVE: The aim of this study was to assess whether an index of muscle fat content is related to maximal fat oxidation rate (FATOX max ) in 58 obese men (mean age 45.5 AE 0.8 (s.e.) y, body weight 95.3 AE 1.4 kg, percentage fat 31.1 AE 0.6%). DESIGN: FATOX max was defined as the highest value of fat oxidation rate, measured by indirect calorimetry, while walking on a treadmill (4.3 km=h) at three different slopes: 0% (40 AE 1% of VO 2max ), 3% (47 AE 1% of VO 2max ) and 6% (58 AE 1% of VO 2max ). Fat-free mass (FFM) and fat mass (FM) were measured with the underwater technique and scans were obtained by computed tomography (CT) at the mid thigh level to assess areas of adipose tissue within skeletal muscle, ie deep adipose tissue (DAT), subcutaneous adipose tissue (SAT), skeletal muscle (M) and low attenuation skeletal muscle (LAM, range of attenuation values 0 -34 Hounsfield units). LAM and DAT were used as indices of skeletal muscle fat content. RESULTS: FATOX max , adjusted for age, was correlated with FFM (r ¼ 0.25, P < 0.05), LAM (r ¼ 0.28, P < 0.05), DAT (r ¼ 0.23, P < 0.05), abdominal visceral adipose tissue (r ¼ 0.26, P < 0.05) and plasma free fatty acid (FFA) levels (r ¼ 0.36, P < 0.05) but not with SAT (r ¼ 0.07). In a stepwise linear multiple regression, plasma FFA, age and LAM significantly predicted FATOX max (r 2 ¼ 0.27). Each independent variable explained about 9% of the FATOX max variance. CONCLUSION: LAM makes a significant but weak contribution to the modulation of fat oxidation during submaximal exercise in obese men.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

et al. 2001

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“…Physical inactivity can lead to obesity, insulin resistance and Type 2 diabetes. Insulin resistance is associated with many abnormalities in muscle tissue such as an increase in muscle lipid content, impaired glycogen synthesis, an enzymatic disposition towards anaerobic generation of energy (high PFK/CS ratio), an increase in the proportion of Type 2 muscle fibres and a reduced capillary density [9,10,11,63,64]. These abnormalities could contribute to the lower VO 2max often seen in Type 2 diabetes.…”

Section: Discussionmentioning

confidence: 99%

Meta-analysis of the effect of structured exercise training on cardiorespiratory fitness in Type 2 diabetes mellitus

et al. 2003

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Aims/hypothesis. Low cardiorespiratory fitness is a powerful and independent predictor of mortality in people with diabetes. Several studies have examined the effects of exercise on cardiorespiratory fitness in Type 2 diabetic individuals. However, these studies had relatively small sample sizes and highly variable results. Therefore the aim of this study was to systematically review and quantify the effects of exercise on cardiorespiratory fitness in Type 2 diabetic individuals. Methods. MEDLINE, EMBASE, and four other databases were searched up to March 2002 for randomized, controlled trials evaluating effects of structured aerobic exercise interventions of 8 weeks or more on cardiorespiratory fitness in adults with Type 2 diabetes. Cardiorespiratory fitness was defined as maximal oxygen uptake (VO 2max ) during a maximal exercise test.Results. Seven studies, presenting data for nine randomized trials comparing exercise and control groups (overall n=266), met the inclusion criteria. Mean exercise characteristics were as follows: 3.4 sessions per week, 49 min per session for 20 weeks. Exercise intensity ranged from 50% to 75% of VO 2max . There was an 11.8% increase in VO 2max in the exercise group and a 1.0% decrease in the control group (post intervention standardized mean difference =0.53, p<0.003). Studies with higher exercise intensities tended to produce larger improvements in VO 2max . Exercise intensity predicted post-intervention weighted mean difference in HbA 1c (r=−0.91, p=0.002 Meta-analysis of the effect of structured exercise training on cardiorespiratory fitness in Type 2 diabetes mellitus N. G. Boulé 1 , G. P. Kenny 1 , E. Haddad 2 , G. A. Wells 3, 4 , R. J. Sigal 1, 3 1 School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada 2 Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada 3 Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada 4 Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada pacities of athletes. In recent decades, VO 2max has had a growing importance in clinical settings and has become the gold standard measure of cardiovascular fitness and exercise capacity [1]. There is evidence from large cohort studies that low cardiorespiratory fitness is a powerful and independent predictor of long-term cardiac mortality in people with diabetes [2,3,4], even after controlling for traditional risk factors such as age, hypercholesterolaemia, smoking, and hypertension and excluding individuals with evidence of coronary ischaemia during testing. Furthermore, in non-diabetic subjects undergoing repeated maximalThe maximal amount of oxygen consumed during exercise (VO 2max ) has been used for decades by exercise physiologists to determine the maximum exercise ca-

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“…Colberg et al, 15 showed that women with visceral obesity have reduced FFA utilization in muscle in the postabsorptive state. Furthermore, Colberg et al 15 and Simoneau et al 16 found that obese women have a decreased oxidative capacity and increased glycolytic and anaerobic capacities of skeletal muscle. This may suggest that not FFA availability in blood, but rather the oxidative enzymes in skeletal muscle may be the limiting factor for the increase in lipid oxidation and thermogenesis.…”

Section: Introductionmentioning

confidence: 99%

The effect of an increased free fatty acid concentration on thermogenesis and substrate oxidation in obese and lean men

2001

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OBJECTIVE:To examine whether a certain increase in plasma free fatty acid (FFA) concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men. DESIGN: The study protocol consisted of a 30 min baseline period after which subjects received an i.v. bolus of 1000 IE heparin. Then consecutive infusions of 4.9, 9.8 and 19.6 mlakg fat-free mass (FFM) Á min of a lipid heparin mixture were started, each infusion for 30 min. SUBJECTS: Eleven obese and 13 lean men with a mean body mass index (BMI) of 34.2 AE 1.0 ( AE s.e.m.) and 23.9 AE 0.5 kgam 2 and age 46.0 AE 1.0 and 42.6 AE 1.5 y, respectively. MEASUREMENTS: Energy expenditure, respiratory exchange ratio (RER) and carbohydrate and lipid oxidation were continuously measured by indirect calorimetry. At the end of each infusion period, a blood sample was taken for FFA, glycerol, insulin, b-hydroxybutyrate, noradrenaline and adrenaline determination. RESULTS: At baseline, plasma FFA levels were comparable in both groups. Lipid heparin infusion increased plasma FFA concentration by 301 AE 47 mmolal and 332 AE 27 mmolal in obese and lean men. Energy expenditure increased similarly in obese and lean men (0.34 AE 0.08 vs 0.40 AE 0.08 kJamin, NS) during lipid heparin infusion, whereas RER decreased similarly in both groups. Lipid oxidation rates were comparable at baseline and increased similarly in obese and lean men (19 AE 5 vs 13 AE 4 mgamin, NS). Baseline plasma insulin levels were higher in the obese, but did not change during lipid heparin infusion. Plasma b-hydroxybutyrate concentrations were similar at baseline, but increased signi®cantly less in the obese during lipid heparin infusion. Baseline noradrenaline and adrenaline concentrations did not differ signi®cantly between groups. During lipid heparin infusion, plasma noradrenaline levels decreased signi®cantly, but plasma adrenaline levels remained unchanged in both groups. CONCLUSION: A certain increase in plasma FFA concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men. The accumulation of fat in obese subjects may therefore be more likely to be due to a defect in adipose tissue lipolysis than a defect in lipid oxidation.

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Skeletal muscle glycolytic and oxidative enzyme capacities are determinants of insulin sensitivity and muscle composition in obese women

Cited by 335 publications

References 0 publications

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

Meta-analysis of the effect of structured exercise training on cardiorespiratory fitness in Type 2 diabetes mellitus

The effect of an increased free fatty acid concentration on thermogenesis and substrate oxidation in obese and lean men

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