Effect of exercise training intensity on abdominal visceral fat and body composition

Nine days of intensive exercise training improves mitochondrial function but not insulin action in adult offspring of mothers with type 2 diabetes

CONTEXT

A close association between insulin resistance and reduced skeletal muscle oxidative capacity has been reported in adult offspring of people with type 2 diabetes (T2D), prompting a hypothesis that insulin resistance may result from mitochondrial dysfunction or vice versa.

OBJECTIVE

We determined whether 9 d of intensive exercise training ameliorates the mitochondrial dysfunction and insulin resistance in offspring of T2D.

METHODS

We compared the response to 9 d of intensive exercise training in eight (seven females, one male) healthy adult offspring of mothers with T2D with eight (six females, two males) nondiabetic controls. Skeletal muscle mitochondrial ATP production was assessed using a luciferase-based assay, and insulin sensitivity was measured using hyperinsulinemic-euglycemic clamps.

RESULTS

Short-term intensive training increased skeletal muscle mitochondrial ATP production and citrate synthase activity similarly in both groups (P < 0.01). In contrast, whereas short-term intensive training reduced the fasting glucose (~5%, P = 0.035) and insulin levels (~40%, P = 0.011) as well as increased the glucose infusion rate during the hyperinsulinemic-euglycemic clamp (~50%, P = 0.028) among controls, no changes in these parameters were observed among offspring except for an increase in fasting glucose (~7%, P = 0.004).

CONCLUSION

A short-term intensive exercise training program was equally effective at increasing skeletal muscle oxidative capacity in nondiabetic people and in the offspring of mothers with diabetes. In contrast, the exercise improved insulin sensitivity only in nondiabetic people but not in the offspring of T2D mothers, revealing dissociation between improvements in skeletal muscle mitochondrial function and insulin sensitivity. The exercise effect on mitochondrial function and insulin sensitivity seems to be mediated by different regulatory pathways.

Efficacy of increasing physical activity to reduce children's visceral fat: a pilot randomized controlled trial

OBJECTIVE

To examine whether differentially targeting physical activity within the context of pilot family-based pediatric weight control treatment results in differential change in abdominal fat, particularly visceral fat.

METHOD

Twenty-nine overweight children (>85(th) body mass index [BMI] percentile) and at least one participating parent were randomly assigned to one of two family-based behavioral weight management conditions that either targeted 1) primarily dietary change (STANDARD; n = 15) or 2) dietary plus physical activity change (ADDED; n = 14). Differences at post-treatment in overall child weight status (e.g., BMI), whole-body composition (measured by dual x-ray absorptiometry), and abdominal fat (measured by waist circumference and magnetic resonance imaging) were assessed using intent-to-treat analyses, as were post-treatment parent BMI and waist circumference. Child and parent physical activity and dietary behavior changes were also evaluated. Results. At post-treatment, overall child weight status, whole-body composition, and child dietary measures did not differ by condition. Children in the ADDED condition tended to have higher physical activity and lower visceral abdominal fat at post-treatment relative to children in the STANDARD condition.

CONCLUSIONS

Increasing physical activity may be important to optimize reductions in abdominal fat, especially visceral fat, among overweight children provided with family-based behavioral weight management treatment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00359957.

Liver and pancreatic fat content and metabolism in healthy monozygotic twins with discordant physical activity

BACKGROUND & AIMS

Ectopic fat in muscle and liver is linked to obesity and type 2 diabetes. Recently, pancreatic lipid accumulation has also been associated with β-cell dysfunction and reduced insulin production, leading to the development of type 2 diabetes. Physical exercise training has been shown to attenuate β-cell dysfunction in patients, but little is known about its effects on pancreatic and hepatic fat accumulation. In this study, we validated in-vivo proton magnetic resonance spectroscopy ((1)H MRS) in pancreatic fat measurement with biochemical measurements in a pig model. Thereafter, the effects of increased physical activity on the amounts of pancreatic and liver fat were studied in eight monozygotic twin pairs who have discordant physical activity and fitness.

METHODS

Pancreatic fat content was studied in 15 pigs using (1)H MRS and/or biochemical analyses. In addition, liver and pancreatic fat were assessed using (1)H MRS in eight monozygotic male twin pairs with 18% mean difference in VO(2max) between the twin brothers.

RESULTS

Twins with higher physical fitness had 23% less liver fat (1.3±1.3% vs. 2.1±2.6%, p=0.022) but no such difference was observed in the pancreatic fat (8.2±9.3% vs. 9.8±8.5%, respectively, p=0.3). Hepatic fat content was inversely associated with VO(2max). A positive association was found between pancreatic and liver fat contents (β=5.18, p=0.012). Pancreatic fat content was also associated with insulin sensitivity indexes and plasma adiponectin and glutamyltransferase concentrations.

CONCLUSIONS

Pancreatic fat content is associated with insulin resistance and hepatic fat content. An active lifestyle seems to beneficially influence hepatic fat metabolism.

The impact of training modalities on the clinical benefits of exercise intervention in patients with cardiovascular disease risk or type 2 diabetes mellitus

Exercise training intervention represents an effective means to reduce adipose tissue mass, improve glycaemic control and increase whole-body oxygen uptake capacity (VO(2peak)) in obesity, metabolic syndrome, type 2 diabetes mellitus (T2DM) and heart disease patients. In this manuscript, we review the impact of different exercise training modalities on clinical benefits of prolonged exercise intervention in these patient (sub)populations. By changing training modalities, significantly greater clinical benefits can be obtained. Greater training frequency and longer programme duration is associated with greater reduction in adipose tissue mass in obesity patients. A greater training frequency (up to 2 days/week) and a longer programme duration (up to 38 weeks) seems to be associated with greater improvements in VO(2peak) in heart disease patients. Longer programme duration and addition of resistance-type exercise further improve glycaemic control in T2DM patients. The first line of evidence seems to indicate that high-intensity interval exercise training has a greater impact on VO(2peak) in heart disease patients and insulin sensitivity in subjects with metabolic syndrome, but not on adipose tissue mass in obese subjects. However, it remains unclear whether addition of resistance-type exercise and continuous higher-intensity endurance-type exercise training are accompanied by greater improvements in VO(2peak) in heart disease patients. Furthermore, the impact of training session duration/volume on adipose tissue mass loss and glycaemic control in obesity and T2DM patients, respectively, is currently unknown. The impact of training frequency on glycaemic control remains to be investigated in T2DM patients.

Intensive exercise: a remedy for childhood obesity?

BACKGROUND

Acute exercise can affect the energy intake regulation, which is of major interest in terms of obesity intervention and weight loss.

OBJECTIVE

To test the hypothesis that intensive exercise can affect the subsequent energy intake and balance in obese adolescents.

DESIGN

The study was conducted in 2009 and enrolled 12 obese pubertal adolescents ages 14.4±1.5 years old. Two exercise and one sedentary sessions were completed. The first exercise (EX(1)) and sedentary session (SED) were randomly conducted 1 week apart. The second exercise session (EX₂) was conducted following 6 weeks of diet modification and physical activity (3×90 min/week) to produce weight loss. Energy intake was recorded, subjective appetite sensation was evaluated using Visual Analogue Scales and energy expenditure was measured using ActiHerats during EX(1), EX₂ and SED.

RESULTS

Total energy intake over the awakened period was significantly reduced by 31% and 18% during the EX(1) and EX(2) sessions compared with the SED session, respectively (p<0.01). Energy balance over the awakened period was negative during EX₁, neutral during EX₂ and positive during SED. There was no significant difference in terms of subjective appetite rates between sessions during the awakened hours.

CONCLUSIONS

Intensive exercise favors a negative energy balance by dually affecting energy expenditure and energy intake without changes in appetite sensations, suggesting that adolescents are not at risk of food frustration.

Oxygen uptake and ratings of perceived exertion at the lactate threshold and maximal fat oxidation rate in untrained adults

The purpose of the study was to examine the relationship between VO(2) and RPE at the lactate threshold (LT) and maximal fat oxidation rate (FAT(MAX)) in untrained adults and determine the stability of the relationship across sex, age, and fitness status. A total of 148 untrained adults (mean age [year] = 30.5 ± 13.9, height [m] = 1.72 ± 0.08 m, body mass [kg] = 82.6 ± 20.5, body fat [%] = 28.7 ± 12.0) completed a continuous incremental VO(2) peak/LT protocol. Fat oxidation rates were determined using indirect calorimetry. The highest recorded fat oxidation rate was chosen as FAT(MAX). The breakpoint in the VO(2)-blood lactate relationship was chosen as LT. RPE was based on the Borg 6-20 scale. Bland-Altman plot analysis demonstrated that VO(2) FAT(MAX) systematically preceded VO(2) LT (mean bias = 1.3 ml kg(-1) min(-1)) with wide limits of agreement (+9.6 to -6.9 ml kg(-1) min(-1)). Multivariate ANOVA revealed a significant difference between VO(2) FAT(MAX) (12.7 ± 7.5 ml kg(-1) min(-1)) and VO(2) LT (14.1 ± 5.9 ml kg(-1) min(-1)) in the total sample (p = 0.04). There were no differences between the intensities when the sample was divided into sex, age, and fitness comparison groups (p values >0.05). RPE FAT(MAX) (9.4 ± 2.5) preceded RPE LT (10.4 ± 2.0) in the total sample (p = 0.008), but was not different across comparison groups (p > 0.05). The present data indicate that the highest rate of fat oxidation slightly precedes the LT in untrained adults. For exercise prescription, a Borg-RPE of 9-12 identifies both FAT(MAX) and LT.

Exercise-induced improvements in cardiorespiratory fitness and heart rate response to exercise are impaired in overweight/obese postmenopausal women

OBJECTIVE

The purpose of this study was to compare the heart rate response to exercise and the exercise-induced improvements in muscle strength, cardiorespiratory fitness and heart rate response between normal-weight and overweight/obese postmenopausal women.

METHODS

Sedentary women (n = 155) were divided into normal-weight (n = 79; BMI <25 kg/m(2); 58.3 ± 8.6 years) and overweight/obese (n = 76; BMI >25 kg/m(2); 58.3 ± 8.6 years) groups, and have their 1-repetition maximum strength (adjusted for body mass), cardiorespiratory fitness and heart rate response to a graded exercise test compared before and after 12 months of a three times-per-week exercise-training program.

RESULTS

Overweight/obese women displayed decreased upper and lower extremity muscle strengths, decreased cardiorespiratory fitness, and lower peak and reserve heart rates compared to normal-weight women. After follow-up, both groups improved their upper (32.9% and 41.5% in normal-weight and overweight/obese women, respectively) and lower extremity(49.5% and 47.8% in normal-weight and overweight/obese women, respectively) muscle strength. However, only normal-weight women improved their cardiorespiratory fitness (6.6%) and recovery heart rate (5 bpm). Resting, reserve and peak heart rates did not change in either group.

CONCLUSIONS

Overweight/obese women displayed impaired heart rate response to exercise. Both groups improved muscle strength, but only normal-weight women improved cardiorespiratory fitness and heart rate response to exercise. These results suggest that exercise-induced improvements in cardiorespiratory fitness and heart rate response to exercise may be impaired in overweight/obese postmenopausal women.

Epidemiology of abdominal obesity among adolescents from a Brazilian State Capital

The objective of this study was to investigate the effects of socioeconomic, demographic and lifestyle factors on abdominal obesity in adolescents from a Brazilian state capital. In this cross-sectional study, 656 high school students (423 girls and 233 boys) from public schools, ranging in age from 14 to 19 yr, were evaluated. Abdominal obesity was identified based on waist circumference. Socioeconomic data (socioeconomic status, household head's education, and school grade), demographic data (gender and age), and information regarding lifestyle (physical activity, eating habits, aerobic fitness, and nutritional status) were collected. Logistic regression was used for multivariate analysis. The prevalence of abdominal obesity was 6.6% (95% confidence interval [CI]: 4.6-8.4). Being in the second (odds ratio [OR] = 0.41; 95% CI: 0.19-0.88) or third year (OR = 0.18; 95% CI: 0.06-0.59) of high school was a protective factor against abdominal obesity. In addition, students presenting low aerobic fitness (OR = 4.10; 95% CI: 1.62-10.4) and those with excess weight (OR = 208.6; 95% CI: 47.7-911.7) had a higher probability of abdominal obesity. In conclusion, demographic factors such as school grade, lifestyle habits, low aerobic fitness and excess weight are associated with central obesity.

Nonprescribed physical activity energy expenditure is maintained with structured exercise and implicates a compensatory increase in energy intake

BACKGROUND

Exercise interventions elicit only modest weight loss, which might reflect a compensatory reduction in nonprescribed physical activity energy expenditure (PAEE).

OBJECTIVE

The objective was to investigate whether there is a reduction in nonprescribed PAEE as a result of participation in a 6-mo structured exercise intervention in middle-aged men.

DESIGN

Sedentary male participants [age: 54 ± 5 y; body mass index (in kg/m²): 28 ± 3] were randomly assigned to a 6-mo progressive exercise (EX) or control (CON) group. Energy expenditure during structured exercise (prescribed PAEE) and nonprescribed PAEE were determined with the use of synchronized accelerometry and heart rate before the intervention, during the intervention (2, 9, and 18 wk), and within a 2-wk period of detraining after the intervention.

RESULTS

Structured prescribed exercise increased total PAEE and had no detrimental effect on nonprescribed PAEE. Indeed, there was a trend for greater nonprescribed PAEE in the EX group (P = 0.09). Weight loss in the EX group (-1.8 ± 2.2 kg compared with +0.2 ± 2.2 kg in the CON group, P < 0.02) reflected only ≈40% of the 300-373 kcal/kg body mass potential energy deficit from prescribed exercise. Serum leptin concentration decreased by 24% in the EX group (compared with 3% in the CON group, P < 0.03), and we estimate that this was accompanied by a compensatory increase in energy intake of ≈100 kcal/d.

CONCLUSIONS

The adoption of regular structured exercise in previously sedentary, middle-aged, and overweight men does not result in a negative compensatory reduction in nonprescribed physical activity. The less-than-predicted weight loss is likely to reflect a compensatory increase in energy intake in response to a perceived state of relative energy insufficiency.

Resistance training for obese, type 2 diabetic adults: a review of the evidence

In both developed and developing countries, increased prevalence of obesity has been strongly associated with increased incidence of type 2 diabetes mellitus (T2DM) in the adult population. Previous research has emphasized the importance of physical activity in the prevention and management of obesity and T2DM, and generic exercise guidelines originally developed for the wider population have been adapted for these specific populations. However, the guidelines traditionally focus on aerobic training without due consideration to other exercise modalities. Recent reviews on resistance training in the T2DM population have not compared this modality with others including aerobic training, or considered the implications of resistance training for individuals suffering from both obesity and T2DM. In short, the optimal mix of exercise modalities in the prescription of exercise has not been identified for it benefits to the metabolic, body composition and muscular health markers common in obesity and T2DM. Similarly, the underlying physical, social and psychological barriers to adopting and maintaining exercise, with the potential to undermine the efficacy of exercise interventions, have not been addressed in earlier reviews. Because it is well established that aerobic exercise has profound effects on obesity and T2DM risk, the purpose of this review was to address the importance of resistance training to obese adults with T2DM.

Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men

The aim of this study was to investigate the effects of very high intensity sprint interval training (SIT) on metabolic and vascular risk factors in overweight/obese sedentary men. Ten men (age, 32.1 ± 8.7 years; body mass index, 31.0 ± 3.7 kg m(-2)) participated. After baseline metabolic, anthropometric, and fitness measurements, participants completed a 2-week SIT intervention, comprising 6 sessions of 4 to 6 repeats of 30-second Wingate anaerobic sprints on an electromagnetically braked cycle ergometer, with 4.5-minute recovery between each repetition. Metabolic, anthropometric, and fitness assessments were repeated post-intervention. Both maximal oxygen uptake (2.98 ± 0.15 vs 3.23 ± 0.14 L min(-1), P = .013) and mean Wingate power (579 ± 24 vs 600 ± 19 W, P = .040) significantly increased after 2 weeks of SIT. Insulin sensitivity index (5.35 ± 0.72 vs 4.34 ± 0.72, P = .027) and resting fat oxidation rate in the fasted state (0.13 ± 0.01 vs 0.11 ± 0.01 g min(-1), P = .019) were significantly higher and systolic blood pressure (121 ± 3 vs 127 ± 3 mm Hg, P = .020) and resting carbohydrate oxidation in the fasted state (0.03 ± 0.01 vs 0.08 ± 0.02 g min(-1), P = .037) were significantly lower 24 hours post-intervention compared with baseline, but these changes were no longer significant 72 hours post-intervention. Significant decreases in waist (98.9 ± 3.1 vs 101.3 ± 2.7 cm, P = .004) and hip (109.8 ± 2.2 vs 110.9 ± 2.2 cm, P = .017) circumferences compared with baseline were also observed after the intervention. Thus, 2 weeks of SIT substantially improved a number of metabolic and vascular risk factors in overweight/obese sedentary men, highlighting the potential for this to provide an alternative exercise model for the improvement of vascular and metabolic health in this population.

Regulation of skeletal muscle transcriptome in elderly men after 6 weeks of endurance training at lactate threshold intensity

A compromised muscle function due to aging, sarcopenia and reduced level of physical activity can lead to metabolic complications and chronic diseases. Endurance exercise counters these diseases by inducing beneficial adaptations whose molecular mechanisms remain unclear. We have investigated the transcriptomic changes following mild-intensity endurance training in skeletal muscle of elderly men. Seven healthy subjects followed an exercise program of cycle ergometer training at lactate threshold (LT) level for 60 min/day, five times/week during six weeks. Physiological and transcriptomic changes were analyzed before and after training. LT training decreased percentage body fat and fasting levels of plasma glucose, while increasing high-density lipoprotein cholesterol and lecithin-cholesterol acyltransferase levels. Transcriptomic analysis revealed fast-to-slow fiber type transition, increased amount of mtDNA encoded transcripts and modulation of 12 transcripts notably related to extracellular matrix (ECM), oxidative phosphorylation (OXPHOS), as well as partially characterized and novel transcripts. The training simultaneously induced the expression of genes related to slow fiber type transition, OXPHOS and ECM, which might contribute to the improvement of glucose and lipid metabolisms and whole body aerobic capacity.

The effects of vigorous physical activity on intra-abdominal fat levels: a preliminary study of middle-aged Japanese men

AIM

To examine the effects of vigorous physical activity (PA) on intra-abdominal fat (IF) levels in obese men.

METHODS

Thirty-seven obese men (mean age: 47.6+/-8.6 years) engaged in a 12-week aerobic exercise program on a regular basis (3 days/week). We divided them into low volume of vigorous PA group (n=19) or high volume of vigorous PA group (n=18), based on the median time spent (34.3min/week) in vigorous PA (over 6.1 metabolic equivalents assessed by a single-axis accelerometer) throughout the program.

RESULTS

Regular exercise reduced IF levels (measured by computed tomography) from 188.1+/-53.9cm(2) to 170.3+/-46.6cm(2) for the low volume of vigorous PA group and from 167.9+/-44.3cm(2) to 137.9+/-40.6cm(2) for the high volume of vigorous PA group. Two-way (time x group) ANOVA revealed no significant interactions for the IF level. However, correlation analysis for all participants showed that time spent in vigorous PA throughout the program significantly correlated to IF reductions after adjusting for initial levels of IF, vigorous PA and weight changes (r=-0.42, P=0.02).

CONCLUSION

This study suggests that vigorous PA may affect IF reductions in obese men.

Non-assisted treadmill training does not improve motor recovery and body composition in spinal cord-transected mice

STUDY DESIGN

Experiments in a mouse model of complete paraplegia.

OBJECTIVES

To evaluate the effect of non-assisted treadmill training on motor recovery and body composition in completely spinal cord-transected mice.

SETTINGS

Laval University Medical Center, Neuroscience Unit, Quebec City, Quebec, Canada.

METHODS

Following a complete low-thoracic (Th9/10) spinal transection (Tx), mice were divided into two groups that were either untrained or trained with no assistance. Training consisted of placing the mice during 15 min with no further intervention (that is no tail pinching or body weight support) on a motorized treadmill (8-10 cm s(-1)) five times per week for 5 weeks. Locomotor performances were assessed weekly in both groups using two complementary locomotor rating scales. After 5 weeks, all mice were killed and adipose tissue, soleus, and extensor digitorum longus muscles were dissected for analyses.

RESULTS

No significant difference in locomotor performances or in muscle fibre type conversion was found between trained and untrained mice. In contrast, body weight, adipose tissue, whole muscle, and individual fibre cross-sectional area (CSA) values were significantly lower in trained compared with untrained animals.

CONCLUSIONS

Non-assisted treadmill training in these conditions did not improve motor performances and contributed to further accentuate body composition changes post-Tx, suggesting that assistance provided manually, robotically, or pharmacologically may be key to spinal learning and recovery of locomotor function and body composition.

Vasopressin V1a receptor polymorphism and interval walking training effects in middle-aged and older people

We assessed whether single nucleotide polymorphism rs1042615 of the vasopressin V1a receptor altered the indices of lifestyle-related diseases in middle-aged and older people (mean+/-SD: 64+/-7 years), and, if so, whether it also altered the effects of interval walking training (IWT). CC, CT, and TT carriers of rs1042615 (42, 118, and 64 men, respectively; 113, 263, and 154 women, respectively) performed IWT. We included 5 sets of 3-minute fast walking at > or =70% peak aerobic capacity for walking and 3-minute slow walking at 40% peak aerobic capacity per day for > or =4 days per week for 5 months. Before IWT, the body mass index and diastolic blood pressure (DBP) for men were 25.1+/-0.3 kg/m(2) (mean+/-SE) and 84+/-1 mm Hg in TT, higher than the 23.6+/-0.4 kg/m(2) and 78+/-1 mm Hg in CC, respectively (P<0.01), differences that disappeared after IWT despite similar training achievement between groups (P>0.6). After IWT, body mass index and DBP decreased in TT (-0.9+/-0.1 kg/m(2) and -5+/-1 mm Hg, respectively), more than in CC (-0.5+/-0.1 kg/m(2) and 1+/-1 mm Hg, respectively; P<0.05), with a greater decrease in low-density lipoprotein cholesterol in TT than CC carriers (P<0.01). The decreases in DBP and low-density lipoprotein cholesterol were still greater in TT carriers even after adjustment for their pretraining values. On the other hand, for women, these parameters before IWT and their changes after IWT were similar among CC, CT, and TT carriers. Thus, polymorphism rs1042615 of the V1a receptor altered body mass index and DBP in middle-aged and older men and the training-induced responses of DBP and low-density lipoprotein cholesterol, whereas women did not show any of these responses.

Effects of exercise training intensity on nocturnal growth hormone secretion in obese adults with the metabolic syndrome

CONTEXT

Abdominal adiposity is associated with reduced spontaneous GH secretion, and an increased incidence of the metabolic syndrome, type 2 diabetes, and cardiovascular disease. Exercise training increases GH secretion, induces abdominal visceral fat loss, and has been shown to improve the cardiometabolic risk factor profile. However, little is known about the effects of endurance training intensity on spontaneous GH release in obese individuals.

OBJECTIVE

Our objective was to examine the effects of 16 wk endurance training on spontaneous 12-h overnight GH secretion in adults with the metabolic syndrome.

DESIGN AND SETTING

This randomized, controlled exercise intervention was conducted at the University of Virginia.

PARTICIPANTS

A total of 34 adults with the metabolic syndrome (mean +/- sem: age: 49.1 +/- 1.8 yr) participated.

INTERVENTION

Participants were randomized to one of three groups for 16 wk: no exercise training (control), low-intensity exercise training, or high-intensity training.

MAIN OUTCOME MEASURE

Change in nocturnal integrated GH area under the curve (AUC) was calculated.

RESULTS

Both exercise training conditions augmented within-group nocturnal GH AUC pretrain to post-training (low-intensity exercise training approximately (upward arrow) 49%, P < 0.05; and high-intensity training approximately (upward arrow) 65%, P < 0.01), and these changes were also greater than the changes in the control group (P < 0.01). The change in nocturnal GH AUC was inversely associated with the change in fat mass across the entire sample (r = -0.34; P = 0.051; n=34) but was not significantly associated with the change in abdominal visceral fat (r = 0.02; P = 0.920; n = 34).

CONCLUSIONS

Sixteen wk of supervised exercise training in adults with the metabolic syndrome increases spontaneous nocturnal GH secretion independent of exercise training intensity.