Randomized trial of exercise effect on intrahepatic triglyceride content and lipid kinetics in nonalcoholic fatty liver disease.

UNLABELLED: Nonalcoholic fatty liver disease (NAFLD) and alterations in hepatic lipoprotein kinetics are common metabolic complications associated with obesity. Lifestyle modification involving diet-induced weight loss and regular exercise decreases intrahepatic triglyceride (IHTG) content and very low density lipoprotein (VLDL) triglyceride (TG) secretion rate. The aim of this study was to evaluate the weight loss-independent effect of following the physical activity guidelines recommended by the Department of Health and Human Services on IHTG content and VLDL kinetics in obese persons with NAFLD. Eighteen obese people (body mass index [BMI]: 38.1 ± 4.6 kg/m(2)) with NAFLD were randomized to 16 weeks of exercise training (45%-55% VO(2peak) , 30-60 minutes × 5 days/week; n = 12) or observation (control; n = 6). Magnetic resonance spectroscopy and stable isotope tracer infusions in conjunction with compartmental modeling were used to evaluate IHTG content and hepatic VLDL-TG and apolipoprotein B-100 (apoB-100) secretion rates. Exercise training resulted in a 10.3% ± 4.6% decrease in IHTG content (P < 0.05), but did not change total body weight (103.1 ± 4.2 kg before and 102.9 ± 4.2 kg after training) or percent body fat (38.9% ± 2.1% before and 39.2% ± 2.1% after training). Exercise training did not change the hepatic VLDL-TG secretion rate (17.7 ± 3.9 µmol/min before and 16.8 ± 5.4 µmol/min after training) or VLDL-apoB-100 secretion rate (1.5 ± 0.5 nmol/min before and 1.6 ± 0.6 nmol/min after training). CONCLUSION: Following the Department of Health and Human Services recommended physical activity guidelines has small but beneficial effects on IHTG content, but does not improve hepatic lipoprotein kinetics in obese persons with NAFLD.

A 6-month supervised employer-based minimal exercise program for police officers improves fitness.

The purpose of the study was to determine the effects of a 6-month supervised, job-specific moderate exercise program in police officers on body composition, cardiovascular and muscular fitness. Body weight (BW), body mass index (BMI), and cardiovascular and muscular fitness were assessed at baseline, after a 6-month supervised fitness program and at 12-month follow-up (18 months). One hundred sixty-five (n = 131 men and n = 34 women) young (mean ± SEM, 26.4 ± 1.9 years), overweight (BMI = 26.2 ± 1.2 kg·m) police officers participated. Aerobic exercise progressed from 3 d·wk, 20 minutes per session at 60% of the heart rate reserve (HRR) to 5 d·wk, 30 minutes per session at 75% of HRR at 3 months, and this level was maintained until 6 months. Muscular strength training progressed using 8 different calisthenics exercises from 3 d·wk, 2 sets of 5 repetitions using the participant's own BW to 5 d·wk, 3 sets of 15 repetitions of the participant's own BW at 3 months, and this level was maintained until 6 months. Cardiovascular and muscular fitness was measured using a 0.25-mile obstacle course incorporating various job-specific exercises and expressed as the physical abilities test (PAT) time. There was a significant reduction in BMI (-0.6 ± 0.2 kg·m, p < 0.001) and BW (-2.8 ± 2.3 kg) and reduction in PAT time (-11.9 ± 2.1%, p < 0.01) from baseline to 6 months. However, BMI (1.4 ± 1.1 kg·m, p < 0.001), BW (5.1 ± 3.0 kg, p < 0.01), and PAT time significantly increased (12.8 ± 2.2%, p < 0.01) from 6 to 18 months. There were no sex by time differences. The practical applications of this study indicate that a supervised, job-specific exercise program for police officers improves fitness and body composition after 6 months in both men and women, but continued supervision of exercise program may be necessary for maintenance of health benefits.

One-set resistance training elevates energy expenditure for 72 h similar to three sets.

To compare the effects of an acute one versus three-set full body resistance training (RT) bout in eight overweight (mean ± SD, BMI = 25.6 ± 1.5 kg m(-2)) young (21.0 ± 1.5 years) adults on resting energy expenditure (REE) measured on four consecutive mornings following each protocol. Participants performed a single one-set or three-set whole body (10 exercises, 10 repetition maximum) RT bout following the American College of Sports Medicine (ACSM) guidelines for RT. REE and respiratory exchange ratio (RER) by indirect calorimetry were measured at baseline and at 24, 48, and 72 h after the RT bout. Participants performed each protocol in randomized, counterbalanced order separated by 7 days. There was no difference between protocols for REE or RER. However, REE was significantly (p < 0.05) elevated (~5% or ~400 kJ day(-1)) in both the protocols at 24, 48, and 72 h post RT bout compared with baseline. There was a no change in RER in both the protocols at 72 h compared to baseline. A one-set RT bout following the ACSM guidelines for RT and requiring only ~15 min to complete was as effective as a three-set RT bout (~35 min to complete) in elevating REE for up to 72 h post RT in overweight college males, a group at high risk of developing obesity. The one-set RT protocol may provide an attractive alternative to either aerobic exercise or multiple-set RT programs for weight management in young adults, due to the minimal time commitment and the elevation in REE post RT bout.

The 1-mile walk test is a valid predictor of VO(2max) and is a reliable alternative fitness test to the 1.5-mile run in U.S. Air Force males.

The purpose of this study was to assess the validity of the 1-mile walk (Rockport Walk Test) as a predictor of VO(2max) and determine whether the 1-mile walk is a reliable alternative to the 1.5-mile run in moderately fit to highly fit U.S. Air Force males. Twenty-four (33.0 +/- 1.5 years) males completed a maximal treadmill VO(2max) (50.3 +/- 1.4 mL/ kg/min), 1-mile walk, and 1.5-mile run. For the 1-mile walk, there were no significant differences between measured and predicted VO(2max) (p = 0.177, r = 0.817). There were no significant differences (p = 0.573) between points scored in the Air Force Fitness Test for the 1-mile walk and 1.5-mile run tests. In conclusion, the 1-mile walk test is a valid predictor of VO(2max) and can be used as an alternative fitness test to the 1.5-mile run in assessing cardiovascular fitness in Air Force males.

Interaction between the UCP2 -866 G>A polymorphism, diabetes, and beta-blocker use among patients with acute coronary syndromes.

OBJECTIVE: UCP2 -866G>A (rs659366) has been implicated in cardiometabolic disease and represents a novel candidate gene for beta-blocker response, particularly among patients with diabetes. We assessed the function of -866G>A and its role as a modifier of beta-blocker treatment outcomes by diabetes status in an acute coronary syndrome (ACS) cohort. METHODS: ACS patients with genetic samples and 12 months of follow-up for cardiac rehospitalizations or death (n=468) were assessed. The influence of -866G>A on beta-blocker treatment outcomes was evaluated in those with diabetes and without. To assess functional correlates of -866G>A, we compared uncoupling protein 2 (UCP2) expression in the skeletal muscle of obese participants by genotype and compared the activity of UCP2 luciferase promoters with -866G and -866A alleles. RESULTS: An interaction between -866G>A and beta-blocker treatment was found in individuals with diabetes (P=0.002) but not those without (P=0.79). Among G/G individuals with diabetes, discharge beta-blocker use was associated with an 80% reduction in cardiac rehospitalization (adjusted hazard ratio: 0.20; 95% confidence interval: 0.04-1.02). In contrast, among A-carrier patients with diabetes, there was an 11-fold increase in cardiac rehospitalizations with discharge beta-blocker therapy (adjusted hazard ratio: 11.75; 95% confidence interval: 1.28-108.2). Promoter activity assays showed that -866G had greater cyclic AMP response element binding protein-responsiveness compared with -866A, and compared with -866A carriers G/G individuals exhibited increased UCP2 expression in the skeletal muscle. CONCLUSION: We identified a significant interaction between -866G>A and beta-blocker response among ACS patients with diabetes. Furthermore, -866G conferred greater gene transcriptional activity than -866A in cell lines and in obese patients. These findings may help us gain insight into the mechanisms underlying the beneficial and detrimental effects of beta-blockers in those with diabetes.

Dietary fat and carbohydrates differentially alter insulin sensitivity during caloric restriction.

BACKGROUND & AIMS: We determined the effects of acute and chronic calorie restriction with either a low-fat, high-carbohydrate (HC) diet or a low-carbohydrate (LC) diet on hepatic and skeletal muscle insulin sensitivity. METHODS: Twenty-two obese subjects (body mass index, 36.5 +/- 0.8 kg/m2) were randomized to an HC (>180 g/day) or LC (<50 g/day) energy-deficit diet. A euglycemic-hyperinsulinemic clamp, muscle biopsy specimens, and magnetic resonance spectroscopy were used to determine insulin action, cellular insulin signaling, and intrahepatic triglyceride (IHTG) content before, after 48 hours, and after approximately 11 weeks (7% weight loss) of diet therapy. RESULTS: At 48 hours, IHTG content decreased more in the LC than the HC diet group (29.6% +/- 4.8% vs 8.9% +/- 1.4%; P < .05) but was similar in both groups after 7% weight loss (LC diet, 38.0% +/- 4.5%; HC diet, 44.5% +/- 13.5%). Basal glucose production rate decreased more in the LC than the HC diet group at 48 hours (23.4% +/- 2.2% vs 7.2% +/- 1.4%; P < .05) and after 7% weight loss (20.0% +/- 2.4% vs 7.9% +/- 1.2%; P < .05). Insulin-mediated glucose uptake did not change at 48 hours but increased similarly in both groups after 7% weight loss (48.4% +/- 14.3%; P < .05). In both groups, insulin-stimulated phosphorylation of c-Jun-N-terminal kinase decreased by 29% +/- 13% and phosphorylation of Akt and insulin receptor substrate 1 increased by 35% +/- 9% and 36% +/- 9%, respectively, after 7% weight loss (all P < .05). CONCLUSIONS: Moderate calorie restriction causes temporal changes in liver and skeletal muscle metabolism; 48 hours of calorie restriction affects the liver (IHTG content, hepatic insulin sensitivity, and glucose production), whereas moderate weight loss affects muscle (insulin-mediated glucose uptake and insulin signaling).

Dietary predictors of visceral adiposity in overweight young adults.

The purpose of the present study was to determine the dietary predictors of visceral adipose tissue (VAT) area in overweight young adults. A total of 109 young adults (fifty males and fifty-nine females) ate ad libitum in a university cafeteria for 14 d. All food and beverages consumed in the cafeteria were measured using observer-recorded weighed plate waste. Food consumption outside the cafeteria (i.e. snacks) was assessed by multiple-pass 24 h recall procedures. VAT was determined using computed tomography. Stepwise regression demonstrated that the best predictor of visceral adiposity in women was total dietary fat (P

Impact of different levels of weight loss on blood pressure in overweight and obese women.

This study sought to determine the impact of different levels of weight loss on blood pressure in overweight/obese women. One hundred fifty-nine overweight/obese women (age 48.7 +/- 9.7, weight 101.3 +/- 18.7 kg, BMI 37.3 +/- 6.6 kg/m(2)) completed a six-month clinical weight loss program that included weekly nutrition, behavior, and exercise instruction. Participants consumed a very-low-energy diet (VLED) for 12 weeks. VLED was followed by four weeks of gradual reintroduction to solid foods. At week 16, participants received a diet to maintain weight or slightly reduce weight (<0.5 lb/week) which they followed for the duration of the study. All lab and blood pressure assessments were performed at baseline and six months. Three groups were formed according to the proportion of weight loss after six months; Group 1 had < 10% (n = 19), Group 2 had 10%-20% (n = 64), and Group 3 had >20% (n = 76) weight loss. Differences in systolic blood pressure (mm Hg) were found in dose response fashion for weight loss at six months with 125 +/- 17 (<10%), 119 +/- 13 (10%-20%), and 117 +/- 15 (>20%; p = 0.005). Differences in diastolic blood pressure (mm Hg) were also found in dose response fashion with 81 +/- 9 (<10%), 77 +/- 9 (10%-20%), and 75 +/- 9 (20%; p = 0.003). These data indicate that increasing weight loss beyond 10% of initial body weight may provide added improvements in blood pressure compared to less than 10% weight loss in overweight or obese women.

Sixty Minutes of Physical Activity per Day Included Within Preschool Academic Lessons Improves Early Literacy.

BACKGROUND: The effects of increases in physical activity (PA) on early literacy skills in preschool children are not known. METHODS: Fifty-four African-American preschool children from a low socioeconomic urban Head Start participated over 8 months. A 2-group, quasi-experimental design was used with one preschool site participating in the PA intervention and a second site participating as the control site. The PA program was designed to promote 300 minutes/week of moderate to vigorous PA academic lessons. Academic achievement related to early literacy and phonological awareness in the areas of rhyming and alliteration were assessed at baseline, 4 and 8 months. RESULTS: Over 8 months, rhyming significantly (p < .01) improved in the PA group (173 ± 12%) compared with the controls (28 ± 8%) resulting in between group differences at 8 months (p < .01). Alliteration significantly (p < .01) improved in the PA group (52 ± 16%) compared with controls (13 ± 5%), resulting in between group differences at 8 months (p < .01). As minutes of exposure to moderate to vigorous PA increased, the change in picture naming (R(2) = .35, p < .05), alliteration (R(2) = .38, p < .05), and rhyming (R(2) = .42, p < .05), increased. CONCLUSION: A teacher-directed PA program is effective at increasing PA and improving early literacy.

Reporting quality of randomized trials in the diet and exercise literature for weight loss.

BACKGROUND: To adequately assess individual studies and synthesize quantitative research on weight loss studies, transparent reporting of data is required. The authors examined the reporting quality of randomized trials in the weight loss literature, focusing exclusively on subject characteristics as they relate to enrollment, allocation, and follow-up. METHODS: An extensive literature review, which included a computerized search of the MEDLINE database, manual searches of bibliographic references, and cross-referencing of 92 review articles was conducted. A checklist, based on CONSORT recommendations, was used to collect information on whether or not authors reported age, gender, co-morbid disease, medication use, race/ethnicity, and postmenopausal status. Also tracked was whether or not initial and final sample size was reported and stratified by gender. RESULTS: Of 604 possible articles, 231 articles met eligibility criteria. Important subject characteristics were not reported as the following breakdown indicates: age (11%), gender (4%), race/ethnicity (86%), co-morbid disease states (34%), and medication use (92%). Additionally, 21% of articles failed to report initial sample size by gender while 69% neglected to report final sample size by gender. CONCLUSION: Inadequate reporting can create difficulties with interpretation and can lead to biased results receiving false credibility. The quality of reporting for weight loss studies needs considerable improvement.

Effects of 16 mo of verified, supervised aerobic exercise on macronutrient intake in overweight men and women: the Midwest Exercise Trial.

BACKGROUND: It is commonly believed that moderate aerobic exercise leads to changes in diet composition, specifically, an increase in carbohydrate intake at the expense of fat intake. OBJECTIVE: The goal was to determine the effects of a supervised, long-term program of exercise on the macronutrient intake of previously sedentary, overweight and moderately obese men and women. DESIGN: Participants (n = 74) were recruited from the university and surrounding communities and were randomly assigned to the exercise or control group. Exercise of moderate intensity was performed for 45 min/d, 5 d/wk, under supervision. Diet intake was ad libitum and was measured for energy and macronutrient composition at baseline and at 5 other occasions across the 16-mo study by use of weighing and measuring techniques. Each measurement consisted of a 2-wk period of direct measurement in the university cafeteria. Food consumption outside the cafeteria during the 2-wk periods (ie, snacks) was measured by multiple-pass 24-h dietary recall procedures. RESULTS: There were no significant differences for men or women between the exercise and control groups from baseline to 16 mo in fat, carbohydrate, or protein intake expressed as grams or as percentages of total energy intake. CONCLUSION: Sixteen months of exercise of moderate intensity does not measurably alter the macronutrient intake of young adults.

The role of exercise for weight loss and maintenance.

Exercise provides a means of increasing energy expenditure and may help adjust energy balance for weight loss and maintenance. At least 30 minutes a day of moderate intensity aerobic exercise per day is recommended for weight loss and maintenance but greater amounts appear to increase the magnitude of weight loss and maintenance. Resistance training has recently been shown to have positive effects on body composition but does not typically show significant decreases in weight. Regardless of weight loss, both aerobic exercise and resistance training have been shown to diminish risk factors for cardiovascular disease and diabetes. Since exercise is only effective if sustained, behavioural strategies such as self-monitoring, goal setting, social support, etc. are used to help individuals start and maintain exercise programs and show improved results compared to exercise programs without behavioural strategies. The available evidence indicates that exercise is an important component of weight loss and perhaps the best predictor of weight maintenance.

Evaluation of a university-based community outreach weight management program.

This study tested the effectiveness of a 6-month university-based community outreach weight management program for overweight/obese adults that utilized standard guidelines from the National Heart, Lung, and Blood Institute (NHLBI). This article also provides practical observations for clinicians desirous to employ a similar program. Fifty-one overweight/obese (34.8 ± 6.6 kg/m(2)) middle-aged (46.6 ± 12.4 y) adults (42 females; 9 males) participated. Participants met weekly for 3 months to be weighed, to report weekly diet and physical activity (PA) data, and to receive instruction for weight management. Participants followed a self-selected dietary plan that included decreasing energy intake by ∼500-1000 kcal/d and consuming a combined 5 fruits and/or vegetables (FV) daily. Participants progressed to a minimum of 150 min of PA per week, wore a pedometer, and recorded daily step counts. Additionally, there was a 3-month follow-up during which participants met monthly but continued tracking FV, PA, and pedometer counts. Body weight decreased significantly (∼0.4-2.1 lbs per week; P < 0.01) during the first 3 months. Weight loss was maintained during the 3-month follow-up. Self-reported energy intake tended to increase during the first 3 months (P < 0.01). PA increased significantly (P < 0.05) beyond recommended minimums and pedometer counts increased significantly (P < 0.01). FV intake averaged below 5 per day and did not change across the study (P = 0.75). Standard treatment guidelines produce modest but consistent weight loss and improvements in PA. The NHLBI recommended approach to weight management is effective for a majority of participants and can be incorporated into a clinical program with relative ease.

Pathogenesis and pathophysiology of the cardiometabolic syndrome.

The cardiometabolic syndrome represents a cluster of metabolic abnormalities that are risk factors for cardiovascular disease. The mechanism(s) responsible for developing the cardiometabolic syndrome is not known, but it is likely that multi-organ insulin resistance, which is a common feature of the cardiometabolic syndrome, is involved. Insulin resistance is an important risk factor for type 2 diabetes and can cause vasoconstriction and renal sodium reabsorption, leading to increased blood pressure. Alterations in adipose tissue fatty acid and adipokine metabolism are involved in the pathogenesis of insulin resistance. Excessive rates of fatty acid release into the bloodstream can impair the ability of insulin to stimulate muscle glucose uptake and suppress hepatic glucose production. Noninfectious systemic inflammation associated with adipocyte and adipose tissue macrophage cytokine production can also cause insulin resistance. In addition, increased free fatty acid delivery to the liver can stimulate hepatic very low-density lipoprotein triglyceride production, leading to dyslipidemia.

Weight loss reduces liver fat and improves hepatic and skeletal muscle insulin sensitivity in obese adolescents.

Obesity in adolescents is associated with metabolic risk factors for type 2 diabetes, particularly insulin resistance and excessive accumulation of intrahepatic triglyceride (IHTG). The purpose of this study was to evaluate the effect of moderate weight loss on IHTG content and insulin sensitivity in obese adolescents who had normal oral glucose tolerance. Insulin sensitivity, assessed by using the hyperinsulinemic-euglycemic clamp technique in conjunction with stable isotopically labeled tracer infusion, and IHTG content, assessed by using magnetic resonance spectroscopy, were evaluated in eight obese adolescents (BMI >or=95th percentile for age and sex; age 15.3 +/- 0.6 years) before and after moderate diet-induced weight loss (8.2 +/- 2.0% of initial body weight). Weight loss caused a 61.6 +/- 8.5% decrease in IHTG content (P = 0.01), and improved both hepatic (56 +/- 18% increase in hepatic insulin sensitivity index, P = 0.01) and skeletal muscle (97 +/- 45% increase in insulin-mediated glucose disposal, P = 0.01) insulin sensitivity. Moderate diet-induced weight loss decreases IHTG content and improves insulin sensitivity in the liver and skeletal muscle in obese adolescents who have normal glucose tolerance. These results support the benefits of weight loss therapy in obese adolescents who do not have evidence of obesity-related metabolic complications during a standard medical evaluation.

Minimal resistance training improves daily energy expenditure and fat oxidation.

UNLABELLED: Long-term resistance training (RT) may result in a chronic increase in 24-h energy expenditure (EE) and fat oxidation to a level sufficient to assist in maintaining energy balance and preventing weight gain. However, the impact of a minimal RT program on these parameters in an overweight college-aged population, a group at high risk for developing obesity, is unknown. PURPOSE: We aimed to evaluate the effect of 6 months of supervised minimal RT in previously sedentary, overweight (mean +/- SEM, BMI = 27.7 +/- 0.5 kg x m(-2)) young adults (21.0 +/- 0.5 yr) on 24-h EE, resting metabolic rate (RMR), sleep metabolic rate (SMR), and substrate oxidation using whole-room indirect calorimetry 72 h after the last RT session. METHODS: Participants were randomized to RT (one set, 3 d x wk(-1), three to six repetition maximums, nine exercises; N = 22) or control (C, N = 17) groups and completed all assessments at baseline and at 6 months. RESULTS: There was a significant (P < 0.05) increase in 24-h EE in the RT (527 +/- 220 kJ x d(-1)) and C (270 +/- 168 kJ x d(-1)) groups; however, the difference between groups was not significant (P = 0.30). Twenty-four hours of fat oxidation (g x d(-1)) was not altered after RT; however, reductions in RT assessed during both rest (P < 0.05) and sleep (P < 0.05) suggested increased fat oxidation in RT compared with C during these periods. SMR (8.4 +/- 8.6%) and RMR (7.4 +/- 8.7%) increased significantly in RT (P < 0.001) but not in C, resulting in significant (P < 0.001) between-group differences for SMR with a trend for significant (P = 0.07) between-group differences for RMR. CONCLUSION: A minimal RT program that required little time to complete (11min per session) resulted in a chronic increase in energy expenditure. This adaptation in energy expenditure may have a favorable impact on energy balance and fat oxidation sufficient to assist with the prevention of obesity in sedentary, overweight young adults, a group at high risk for developing obesity.

Changes in resting metabolic rate and substrate oxidation after 16 months of exercise training in overweight adults.

PURPOSE: To determine whether 16 months of moderate-intensity exercise training changes resting metabolic rate (RMR) and substrate oxidation in overweight young adults. METHODS: Participants were randomly assigned to nonexercise control (CON, 18 women, 15 men) or exercise (EX, 25 women, 16 men) groups. EX performed supervised and verified exercise 3-5 d/wk, 20-45 min/session, at 60-75% of heart-rate reserve. Body mass and composition, maximal oxygen consumption (VO2max), RMR, and resting substrate oxidation were assessed at baseline and after 9 and 16 months of training. RESULTS: EX men had significant decreases from baseline to 9 months in body mass (94.6+/-12.4 to 89.2+/-9.5 kg) and percent fat (28.3+/-4.6 to 24.5+/-3.9). CON women had significant increases in body mass (80.2+/-8.1 to 83.2+/-9.2 kg) from baseline to 16 months. VO2max increased significantly from baseline to 9 months in the EX men (3.67+/-0.62 to 4.34+/-0.58 L/min) and EX women (2.53+/-0.32 to 3.03+/-0.42 L/min). RMR increased from baseline to 9 months in EX women (1,583+/-221 to 1,692+/-230 kcal/d) and EX men (1,995+/-184 to 2,025+/-209 kcal/d). There were no significant differences within genders for either EX or CON in fat or carbohydrate oxidation. Fat oxidation was significantly higher for women than for men at 9 months in both CON and EX groups. CONCLUSIONS: Regular moderate-intensity exercise in healthy, previously sedentary overweight and obese adults increases RMR but does not alter resting substrate oxidation. Women tend to have higher RMR and greater fat oxidation, when expressed per kilogram fat-free mass, than men.

Nonalcoholic fatty liver disease is associated with hepatic and skeletal muscle insulin resistance in overweight adolescents.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) and insulin resistance are common in overweight adolescents. OBJECTIVE: The purpose of this study was to determine the relation between NAFLD and insulin sensitivity in liver and skeletal muscle by studying overweight adolescents with a normal or high intrahepatic triglyceride (IHTG) content, who were matched for age, sex, body mass index (BMI; in kg/m(2)), and Tanner stage. DESIGN: Stable-isotope-labeled tracer infusion and the hyperinsulinemic-euglycemic clamp procedure were used to assess skeletal muscle and hepatic insulin sensitivity, and magnetic resonance spectroscopy was used to assess the IHTG content in 10 overweight (BMI = 35.9 +/- 1.3) adolescents with NAFLD (IHTG = 28.4 +/- 3.4%) and 10 overweight (BMI = 36.6 +/- 1.5) adolescents with a normal IHTG content (3.3 +/- 0.5%). RESULTS: The baseline plasma glucose concentration and the rate of appearance of glucose in plasma were the same in subjects with a normal (87.1 +/- 1.2 mg/dL, 16.2 +/- 1.1 micromol . kg fat-free mass(-1) . min(-1)) or high (89.2 +/- 2.5 mg/dL, 16.3 +/- 1.2 micromol . kg fat-free mass(-1) . min(-1)) IHTG content. However, compared with subjects who had a normal IHTG content, subjects with NAFLD had a lower hepatic insulin sensitivity index, based on baseline glucose kinetics and insulin concentrations (4.0 +/- 0.5 compared with 2.4 +/- 0.4; P < 0.05) and an impaired increase in glucose uptake during insulin infusion (169 +/- 28.1% compared with 67 +/- 9.6% above baseline; P < 0.01). In addition, the plasma triglyceride concentration was greater and the plasma HDL-cholesterol concentration was lower in subjects with NAFLD than in those with a normal IHTG content. CONCLUSION: An elevated IHTG content in overweight adolescents is associated with dyslipidemia and with insulin-resistant glucose metabolism in both liver and skeletal muscle.

The influence of calcium consumption on weight and fat following 9 months of exercise in men and women.

BACKGROUND: There is some evidence that calcium consumption improves weight loss during energy restriction but the effects of calcium consumption in conjunction with chronic exercise are unknown. OBJECTIVE: The purpose of the study was to determine the degree to which calcium consumption influences weight and fat weight change as a result of 9 months of verified supervised exercise in the absence of energy restriction. METHODS: Participants were 50 previously sedentary, overweight and moderately obese men (n=20) and women (n=30). Exercise of moderate intensity was performed for 45 min/d, 5 d/wk, under supervision. Diet intake was ad libitum and was measured for energy, macronutrient and micronutrient composition at baseline, 4 and 9 months by use of observer recorded weighed plate waste and multiple-pass 24-h dietary recall procedures. RESULTS: Average calcium consumption was 987 +/- 389 mg/day for men and 786 +/- 276 mg/day for women. Weight change over the 9 months was -4.6 +/- 4.6 kg for men and 0.2 +/- 3.3 kg for women. Calcium consumption was associated with weight change (r =-0.47, p<0.05) in men. The calcium to protein ratio was associated with weight change (r=0.56) and fat weight change (r=-0.53) in men. There was no observed association between calcium and weight or fat weight change in women. CONCLUSION: Weight and fat weight loss as a result of nine months of moderate intensity exercise may be improved by increased calcium consumption in men but was not observed in women.

Six months of supervised high-intensity low-volume resistance training improves strength independent of changes in muscle mass in young overweight men.

To determine the effects of a 6-month supervised low-volume resistance training (RT) program (1 set, 85-90%, one repetition maximum, 1RM, 3 d x wk(-1)) on muscular strength (1RM) and skeletal muscle mass (SMM) in previously sedentary, overweight men on an ad libitum diet. Nineteen men were randomly assigned to a control (CON, n = 8) or RT (n = 11) group. The exercise protocol consisted of 5 upper- and 4 lower-body exercises using weight machines. CON maintained their sedentary lifestyle. One RM for upper body (chest press [CP] + lat pull-down [LPD]) and lower body (leg press [LP]) and SMM were assessed at baseline, and at 3 and 6 months. Adherence was 96 +/- 2% with an average time to complete each exercise session of 15 +/- 2 minutes. Volume completed per exercise session significantly increased from baseline (2,812 +/- 670 kg) to 6 months (6,411 +/- 2,128 kg). There was a group by time interaction in 1RM for CP, LPD, and LP. Upper-body strength increased significantly (p < 0.001) (31.3 +/- 9.3%) from baseline to 3 months and from 3 to 6 months (17.9 +/- 8.7%). Lower-body strength also increased significantly from baseline to 3 months (17.8 +/- 16.6%) and from 3 to 6 months (32.0 +/- 33.7%). No changes in upper- or lower-body strength occurred in the CON group. There was no group by time interaction for SMM (CON, 34.5 +/- 2.9 kg vs. RT, 34.2 +/- 2.9 kg; p > 0.05) or for energy intake (p > 0.05). In conclusion, a single set resistance training program at 85% of 1RM, 3 d x wk(-1) resulted in continued increases in muscular strength and a very high adherence rate over a 6-month period in sedentary, overweight men independent of significant changes in SMM. This training protocol may increase adherence and produce long-term increases in muscular fitness as part of an adult fitness program.