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

A combined continuous and interval aerobic training improves metabolic syndrome risk factors in men

Individuals with metabolic syndrome have significantly higher risk of cardiovascular disease and type 2 diabetes leading to premature death mortality. Metabolic syndrome has a complex etiology; thus, it may require a combined and multi-targeted aerobic exercise regimen to improve risk factors associated with it. Therefore, the aim of this study was to evaluate the effect of combined continuous and interval aerobic training on patients with metabolic syndrome. Thirty adult male with metabolic syndrome (54±8 years) were randomly divided into two groups: test training group (TTG; n=15) and control group (CG; n=15). Subjects in TTG performed combined continuous and interval aerobic training using a motorized treadmill three times per week for 16 weeks. Subjects in CG were advised to continue with their normal activities of life. Twenty-two men completed the study (eleven men in each group). At the end of the study, in TTG, there were significant (for all, P<0.05) reductions in total body weight (−3.2%), waist circumference (−3.43 cm), blood pressure (up to −12.7 mmHg), and plasma insulin, glucose, and triacylglyceride levels. Moreover, there were significant (for all, P<0.05) increases VO₂max (−15.3%) and isometric strength of thigh muscle (28.1%) and high-density lipoprotein in TTG. None of the above indices were changed in CG at the end of 16-week study period. Our study suggests that adoption of a 16-week combined continuous and interval aerobic training regimen in men with metabolic syndrome could significantly reduce cardiovascular risk factors in these patients.

Wide housing space and chronic exercise enhance physical fitness and adipose tissue morphology in rats

The current cages commonly used in animal experiments can prevent rats from engaging in most forms of natural locomotion behaviors. These animals tend to exhibit sedentary habits. Here, we show that a combination of wide housing space and training exercise helps to reduce white adipose mass and to increase brown adipose mass. Thus, this combination is a useful strategy for truly enhancing the physical fitness of captive rats commonly used in exercise-related interventional studies and to maximize their welfare.

Effects of Endurance Training at the Crossover Point in Women with Metabolic Syndrome

INTRODUCTION

On the basis of theoretical evidence, intensity at the crossover point (COP) of substrate utilization could be considered as potential exercise intensity for metabolic syndrome (MetS). This study aimed to examine the effects of a training program at COP on exercise capacity parameters in women with MetS and to compare two metabolic indices (COP and the maximal fat oxidation rate point LIPOXmax®) with ventilatory threshold (VT).

METHODS

Nineteen women with MetS volunteered to perform a 12-wk training program on a cycle ergometer, with intensity corresponding to COP. Pre- and posttraining values of anthropometric and exercise capacity parameters were compared to determine the effects of exercise training. The pre-post training change of COP, LIPOXmax®, and VT were also investigated.

RESULTS

After training, anthropometric parameters were significantly modified, with reduction of body mass (3.0% ± 3.0%, P < 0.001), fat mass (3.3% ± 3.4%, P < 0.001), and body mass index (3.2% ± 3.4%, P < 0.001). Exercise capacity was improved after the training program, with significant increase of maximal power output (25.0% ± 18.4%, P < 0.001) and maximal oxygen uptake (V˙O2max, 9.0% ± 11.2%; P < 0.01). Lastly, when expressed in terms of power output, COP, LIPOXmax®, and VT occurred at a similar exercise intensity, but the occurrence of these three indices is different when expressed in terms of oxygen uptake, HR, or RPE.

CONCLUSIONS

This study highlights the effectiveness of a 12-wk training program at COP to improve physical fitness in women with MetS. The relations between metabolic indices and VT in terms of power output highlight the determination of VT from a shorter maximal exercise as a useful method for determining metabolic indices in MetS.

Physical exercise antagonizes clinical and anatomical features characterizing Lieber-DeCarli diet-induced obesity and related metabolic disorders

BACKGROUND & AIMS

Lieber-DeCarli diet has been used to induce obesity and non-alcoholic steatohepatitis (NASH). As scarce anatomical and clinical-related information on this diet model exists and being exercise an advised strategy to counteract metabolic diseases, we aimed to analyze the preventive (voluntary physical activity - VPA) and therapeutic (endurance training - ET) effect of exercise on clinical/anatomical features of rats fed with Lieber-DeCarli diet.

METHODS

In the beginning of the protocol, Sprague-Dawley rats were divided into standard-diet sedentary (SS, n = 20), standard-diet VPA (SVPA, n = 10), high-fat diet sedentary (HS, n = 20) and high-fat diet VPA (HVPA, n = 10) groups. After 9-weeks, half (n = 10) of SS and HS groups were engaged in an ET program (8 wks/5 d/wk/60 min/day). At this time, a blood sample was collected for biochemical analysis. At the end of protocol (17-weeks) anatomic measures were assessed. Heart, liver, femur and visceral fat were weighted and blood was collected again. Liver section was used for histopathological examination.

RESULTS

At 17-weeks, high-fat diet increased visceral adiposity (HS vs. SS), which was counteracted by both exercises. However, ET was the only intervention able to diminished obesity-related measures and the histological features of NASH. Moreover, blood analysis at 9 weeks showed that high-fat diet increased ALT, AST, cholesterol and HDL while VLDL and TG levels were decreased (HS vs. SS). Notably, although these parameters were counteracted after 9-weeks of VPA, they were transitory and not observed after 17-weeks.

CONCLUSIONS

ET used as a therapeutic tool mitigated the clinical/anatomical-related features induced by Liber-DeCarli diet, thus possibly contributing to control obesity and metabolic disorders.

Endurance training-induced increase in circulating irisin levels is associated with reduction of abdominal visceral fat in middle-aged and older adults

To elucidate the effects of endurance training on circulating irisin levels in young and middle-aged/older adults, and to determine the association between endurance training-induced alteration of irisin and reduction in body fat. Twenty-five healthy young (age 21 ± 1 years; 16 men, 9 women) and 28 healthy middle-aged/older adults (age 67 ± 8 years; 12 men, 16 women) participated in the study. Each age cohort was divided into two groups: the endurance-training group (14 young, 14 middle-aged/older) and the control group. Subjects in the training groups completed an 8-week endurance-training program (cycling at 60-70% peak oxygen uptake [V˙O_2peak] for 45 min, 3 days/week). Before and after the intervention, we evaluated serum irisin level, V˙O_2peak, and body composition. The increase in V˙O_2peak in the young and middle-aged/older training groups after the intervention period was significantly greater than those in the young and middle-aged/older control groups (P < 0.05). Serum irisin level was significantly increased in the middle-aged/older training group after the intervention period (P < 0.01), but not in the young training group. Furthermore, in the middle-aged/older training group, the endurance training-induced reduction in visceral adipose tissue area was negatively correlated with the change in serum irisin level (r = −0.54, P < 0.05). These results suggest a possible role for secreted irisin in the exercise-induced alteration of abdominal visceral fat in middle-aged and older adults.

A boxing-oriented exercise intervention for obese adolescent males: findings from a pilot study

In New Zealand, obese Māori and Pasifika adolescents are at risk of numerous cardio-metabolic conditions with raising physical activity levels being proposed as a useful intervention. The present study used a mixed method design to explore the effects of a non-contact boxing-oriented training programme designed in terms of improvements to cardio-metabolic variables. Traditional recruitment strategies (media, referrals) were employed, with limited success leading to 3 adolescent boys (14-15 y) participating in the pilot intervention. Exercise sessions included 30 minutes of non-contact boxing training, followed by 30 minutes of progressive resistance training. Participants attended three 1h training sessions each week, for a total of 12 weeks. Physiological variables included anthropometric indices, visceral fat thickness, central blood pressures, central arterial stiffness (augmentation index: AIx), and carotid arterial stiffness (β). Results revealed that there was no trend for change in body weight (125.5 ± 12.1 kg vs. 126.5 ± 11.0 kg) or BMI (39.3 ± 4.1 kg·m(-2) vs. 39.0 ± 4.6 kg·m(-2)). However, there was a moderate decrease in visceral fat thickness (4.34 ± 2.51 cm vs 3.65 ± 1.11 cm, d = 0.36). There was no change in central pulse pressure (38.7 ± 7.3 mmHg vs. 38.3 ± 5.0 mmHg), however, there was a small improvement in β (3.01 ± 0.73 vs. 2.87 ± 0.84, d = 0.18). Focus group interview data with participants and their parents were used to explore issues related to motivation to participation. Results revealed participants commented on how the programme has led to new friendships, changes to their physical appearance, and increased physical fitness. Parents commented on increased self-confidence, better performance in school, and a willingness to take part in new activities. In conclusion, it appears participating in the boxing oriented training programme was motivating to participants who engaged and had some physiological benefits in obese adolescent boys of Māori and Pasifika descent. However, despite these positive attributes, poor recruitment rates suggest that future work should focus on identifying the barriers to engagement. Key pointsA boxing-oriented intervention was developed for use with Māori and Pasifika adolescents to improve cardiometabolic risk factors.While results indicate positive benefits of participation in the 60-minute boxing-orientated programme, only three participants were recruited despite intense promotion.Future research should investigate the efficacy of strategies designed to raise intentions to exercise.

Reversal of metabolic adaptations induced by physical training after two weeks of physical detraining

The present study aimed to evaluate the effect of two weeks of physical detraining (PD) on energy balance components, white adipose tissue (WAT) metabolism, body weight (BW) and adiposity. Male C57BL/6J mice were assigned into groups sedentary (S, n = 20) and trained (T, n = 18). Physical training (PT) consisted of two 1.5 h daily sessions of swimming, 5 times/week for 4 weeks. After the PT, some of the S (S4, n = 10) and T (T4, n = 8) animals were sacrificed, and the others were kept sedentary (S6, n = 10) or detrained for two weeks (D, n = 10). After PT, the T group showed lower BW compared with S group, but PD reversed this response. The BW gains were 4%, 3% and 6.3% in S, S6 and D groups, respectively, however the T group decreased by 1.7%. T4 and D groups showed lower visceral fat depots and larger heart and left ventricle weights compared with S4 and S6 groups. Food intake, oxygen consumption at rest and fasting-induced weight loss were higher in T4 group compared with S4, and this was reversed by PD. Serum concentration of insulin, the activity of enzyme FAS and mean blood pressure did not differ among groups, but the concentration of leptin and resting heart rate were lower in T4 and D groups compared with S4 and S6 groups. T4 group increased lipolytic activity stimulated by isoproterenol and citrate synthase activity, which were reversed by PD. In conclusion, PD reversed the components of energy balance by reducing food intake and resting metabolism, and impaired WAT lipolytic activity, but not lipogenic activity. These changes resulted in remodeling of BW, but not adiposity.

Physical activity and risk of fatty liver in people with different levels of alcohol consumption: a prospective cohort study

OBJECTIVE

To investigate whether physical activity affects the future incidence of fatty liver in people with never-moderate and heavy alcohol consumption.

DESIGN

Prospective cohort study.

SETTING

Health check-up programme at Meiji Yasuda Shinjuku Medical Center in Shinjuku Ward, Tokyo, Japan.

POPULATION

A total of 10,146 people aged 18 years or older without fatty liver enrolled through baseline surveys conducted from 2005 to 2007. They were grouped into never-moderate alcohol drinkers (n=7803) and heavy alcohol drinkers (n=2343) and followed until 2013.

MAIN OUTCOME MEASURE

Incident fatty liver diagnosed by ultrasound.

RESULTS

During a mean follow-up of 4.4 years (34,648 person-years), 1255 never-moderate alcohol drinkers developed fatty liver; 520 heavy alcohol drinkers developed fatty liver during a mean follow-up of 4.1 years (9596 person-years). For never-moderate alcohol drinkers, engaging in >3×/week of low-intensity (HR=0.82, 95% CI 0.71 to 0.96) and moderate-intensity (HR=0.56, 95% CI 0.39 to 0.81) physical activity significantly reduced incident fatty liver compared with those who engaged in physical activity <1×/week. For vigorous-intensity physical activity, frequencies of 2×/week (HR=0.57, 95% CI 0.38 to 0.86) and >3×/week (HR=0.55, 95% CI 0.38 to 0.79) were significantly associated with lower risk of incident fatty liver. In propensity-adjusted models, these significant associations still remained. By contrast, in heavy alcohol drinkers, there were no significant associations between the type or frequency of physical activity and incident fatty liver.

CONCLUSIONS

Physical activity had an independent protective effect on incident fatty liver only in the never-moderate alcohol drinkers, and the preventive effect increased with higher frequencies and intensities of physical activity.

A preliminary study: effects of football training on glucose control, body composition, and performance in men with type 2 diabetes

The effects of regular football training on glycemic control, body composition, and peak oxygen uptake (VO₂ peak) were investigated in men with type 2 diabetes mellitus (T2DM). Twenty-one middle-aged men (49.8 ± 1.7 years ± SEM) with T2DM were divided into a football training group (FG; n = 12) and an inactive control group (CG; n = 9) during a 24-week intervention period (IP). During a 1-h football training session, the distance covered was 4.7 ± 0.2 km, mean heart rate (HR) was 83 ± 2% of HRmax, and blood lactate levels increased (P < 0.001) from 2.1 ± 0.3 to 8.2 ± 1.3 mmol/L. In FG, VO₂ peak was 11% higher (P < 0.01), and total fat mass and android fat mass were 1.7 kg and 12.8% lower (P < 0.001), respectively, after IP. After IP, the reduction in plasma glucose was greater (P = 0.02) in FG than the increase in CG, and in FG, GLUT-4 tended to be higher (P = 0.072) after IP. For glycosylated hemoglobin (HbA1), an overall time effect (P < 0.01) was detected after 24 weeks. After IP, the number of capillaries around type I fibers was 7% higher (P < 0.05) in FG and 5% lower (P < 0.05) in CG. Thus, in men with T2DM, regular football training improves VO₂ peak, reduces fat mass, and may positively influence glycemic control.

Body weight and body composition of depot medroxyprogesterone acetate users

OBJECTIVES

Weight gain is a concern with the contraceptive depot-medroxyprogesterone acetate (DMPA); however, this issue remains controversial. The objective of this study was to compare body weight (BW) and body composition (BC) in DMPA and copper intrauterine device (IUD) users at baseline and after one year of use.

STUDY DESIGN

We enrolled new DMPA users and age and weight matched new IUD users into this prospective study. Weight and height were measured, BC (fat and lean mass) was evaluated using dual-energy X-ray absorptiometry, and physical activity was assessed at baseline and at 12 months. Student's paired t test and the Wilcoxon paired test for matched samples were used.

RESULTS

Ninety-seven women were enrolled for the study; 26 matched pairs continued using the initial method for at least one year, and completed the baseline and 12 month assessments. An increase of 1.9 kg occurred in BW (p=.02) in DMPA users at 12 months of use, resulting from an increase in fat mass of 1.6 kg (p=.03). Weight remained stable in IUD users; however, there was an increase in lean mass at 12 months of use (p=.001). The number of women practicing physical activity increased in this group. There was a significant difference between the groups regarding the variation in the percentage of central fat (p=.04).

CONCLUSION

Weight gain in the DMPA group after the first year of use resulted from an increase in fat mass. Weight remained stable in the IUD group; however, an increase in lean mass and a reduction in localized abdominal fat mass occurred, possibly because more users were practicing physical activity.

IMPLICATIONS STATEMENT

There was a greater increase in body weight in DMPA users compared to TCu380A IUD users in the first year of use of the contraceptive method. Furthermore, the weight increase in users of DMPA occurred principally as the result of an increase in fat mass. Physical activity probably could increase the lean mass in the users of TCu380A IUD.

Does IRISIN Have a BRITE Future as a Therapeutic Agent in Humans?

The epidemic of obesity has contributed to the rapid rise in comorbid conditions such as cardiovascular disease, type 2 diabetes, sleep apnea, and hypertension among others. Therefore, there is a critical need to develop therapeutic strategies to reduce the prevalence of the disease. Skeletal muscle cells secrete signaling cytokines/peptides (referred to as myokines) that act in autocrine, paracrine, and endocrine fashion. Myokines have been hypothesized to contribute to the immediate and chronic benefits of exercise and may thus serve as attractive therapeutic agents for the treatment of obesity. The recent discovery of the irisin, a proposed myokine, has gained much attention over the last two years as a potential therapeutic agent. Preliminary studies demonstrated that irisin has the potential to induce "browning" of white adipocytes in mice. If these findings in mice could be translated to humans, irisin could be a potential therapeutic agent for the treatment of obesity. Limitations with the available antibodies, however, have raised concerns regarding the detectability of irisin in circulation. Moreover, the gene encoding irisin, FNDC5, is expressed robustly not only in muscle but also in various white adipose tissues (WAT) in humans, raising the possibility for increased thermogenesis through autocrine mechanisms. Here we will discuss the browning of WAT, the discovery of irisin, and its potential role in improving metabolic health in humans.

High-intensity exercise training for the prevention of type 2 diabetes mellitus

Aerobic exercise training and diet are recommended for the primary prevention of type 2 diabetes mellitus and cardiovascular disease. The American Diabetes Association (ADA) recommends that adults with prediabetes engage in ≥ 150 minutes per week of moderate activity and target a 7% weight loss. However, traditional moderate-intensity (MI) exercise training programs are often difficult to sustain for prediabetic adults; a commonly cited barrier to physical activity in this population is the "lack of time" to exercise. When matched for total energy expenditure, high-intensity (HI) exercise training has a lower overall time commitment compared with traditional low-intensity (LI) or MI exercise training. Several recent studies comparing HI exercise training with LI and MI exercise training reported that HI exercise training improves skeletal muscle metabolic control and cardiovascular function in a comparable and/or superior way relative to LI and MI exercise training. Although patients can accrue all exercise benefits by performing LI or MI activities such as walking, HI activities represent a time-efficient alternative to meeting physical activity guidelines. High-intensity exercise training is a potent tool for improving cardiometabolic risk for prediabetic patients with limited time and may be prescribed when appropriate.

Effects of exercise intensity on postprandial improvement in glucose disposal and insulin sensitivity in prediabetic adults

BACKGROUND

A single bout of exercise improves postprandial glycemia and insulin sensitivity in prediabetic patients; however, the impact of exercise intensity is not well understood. The present study compared the effects of acute isocaloric moderate (MIE) and high-intensity (HIE) exercise on glucose disposal and insulin sensitivity in prediabetic adults.

METHODS

Subjects (n=18; age 49±14 y; fasting glucose 105±11 mg/dL; 2 h glucose 170±32 mg/dL) completed a peak O2 consumption/lactate threshold (LT) protocol plus three randomly assigned conditions: 1) control, 1 hour of seated rest, 2) MIE (at LT), and 3) HIE (75% of difference between LT and peak O2 consumption). One hour after exercise, subjects received an oral glucose tolerance test (OGTT). Plasma glucose, insulin, and C-peptide concentrations were sampled at 5- to 10-minute intervals at baseline, during exercise, after exercise, and for 3 hours after glucose ingestion. Total, early-phase, and late-phase area under the glucose and insulin response curves were compared between conditions. Indices of insulin sensitivity (SI) were derived from OGTT data using the oral minimal model.

RESULTS

Compared with control, SI improved by 51% (P=.02) and 85% (P<.001) on the MIE and HIE days, respectively. No differences in SI were observed between the exercise conditions (P=.62). Improvements in SI corresponded to significant reductions in the glucose, insulin, and C-peptide area under the curve values during the late phase of the OGTT after HIE (P<.05), with only a trend for reductions after MIE.

CONCLUSION

These results suggest that in prediabetic adults, acute exercise has an immediate and intensity-dependent effect on improving postprandial glycemia and insulin sensitivity.

Continuous exercise but not high intensity interval training improves fat distribution in overweight adults

OBJECTIVE

The purpose of this study was to assess the effect of high intensity interval training (HIIT) versus continuous aerobic exercise training (CONT) or placebo (PLA) on body composition by randomized controlled design.

METHODS

Work capacity and body composition (dual-energy X-ray absorptiometry) were measured before and after 12 weeks of intervention in 38 previously inactive overweight adults.

RESULTS

There was a significant group × time interaction for change in work capacity (P < 0.001), which increased significantly in CONT (23.8 ± 3.0%) and HIIT (22.3 ± 3.5%) but not PLA (3.1 ± 5.0%). There was a near-significant main effect for percentage trunk fat, with trunk fat reducing in CONT by 3.1 ± 1.6% and in PLA by 1.1 ± 0.4%, but not in HIIT (increase of 0.7 ± 1.0%) (P = 0.07). There was a significant reduction in android fat percentage in CONT (2.7 ± 1.3%) and PLA (1.4 ± 0.8%) but not HIIT (increase of 0.8 ± 0.7%) (P = 0.04).

CONCLUSION

These data suggest that HIIT may be advocated as a time-efficient strategy for eliciting comparable fitness benefits to traditional continuous exercise in inactive, overweight adults. However, in this population HIIT does not confer the same benefit to body fat levels as continuous exercise training.

The effect of a lifestyle intervention on metabolic health in young women

With the increasing obesity rates in Western countries, an effective lifestyle intervention for fat reduction and metabolic benefits is needed. High-intensity intermittent exercise (HIIE), Mediterranean eating habits (Mediet), and fish oil (ω-3) consumption positively impact metabolic health and adiposity, although the combined effect has yet to be determined. A 12-week lifestyle intervention on adiposity, insulin resistance, and interleukin-6 (IL-6) levels of young overweight women was administered. Thirty women with a body mass index of 26.6±0.5 kg/m(2), blood pressure of 114/66±1.9/1.5 mmHg, and age of 22±0.8 years were randomly assigned to either an intervention group receiving Mediet advice, daily ω-3 supplementation, and HIIE 3 days/week for 12 weeks or a control group. The group receiving Mediet advice, daily ω-3 supplementation, and HIIE experienced a significant reduction in total body fat mass (P<0.001), abdominal adiposity (P<0.05), waist circumference (P<0.001), systolic blood pressure (P<0.05), fasting plasma insulin (P<0.05), IL-6 (P<0.001), and triglycerides (P<0.05). The greatest decreases in fasting plasma insulin (P<0.05) and IL-6 (P<0.001) occurred by week 6 of the intervention. Significant improvements in eating habits (P<0.05) and aerobic fitness (P<0.001) were also found following the intervention. A multifaceted 12-week lifestyle program comprising a Mediet, ω-3 supplementation, and HIIE induced significant improvements in fat loss, aerobic fitness, and insulin and IL-6 levels, positively influencing metabolic health.

Effects of exercise program on physiological functions in postmenopausal women with metabolic syndrome

The purpose of this study was to examine effects of mixed interval aerobic and strength training (MAST) program on physiological functions in older women with metabolic syndrome. 12 subjects were randomly assigned to the exercise group (16-week MAST program) or the control group. Outcomes included oxygen uptake (VO_2max), cerebral blood flow velocity (BFV) and cognitive functions. The exercise group demonstrated increased VO_2max and certain improvements in cognitive functions. No changes were observed in BFV for both groups. These results can be used as a preliminary data for planning larger studies.

Effect of exercise on abdominal fat loss in men and women with and without type 2 diabetes

OBJECTIVE

To examine the effect of exercise on abdominal adipose tissue in adults with and without type 2 diabetes mellitus (T2DM).

DESIGN

Post hoc analysis of two randomised controlled trials.

SETTING

Outpatient secondary prevention programme in Baltimore, Maryland, USA.

PARTICIPANTS

97 men and women with prehypertension, stage 1 or medically controlled hypertension. 49% of the sample was also diagnosed with T2DM.

INTERVENTION

All participants completed a 26-week (6.5 months) supervised aerobic and resistance exercise programme following American College of Sports Medicine guidelines.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcomes in this post hoc analysis were total abdominal adipose tissue (TAT), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) measured by MRI. Secondary outcomes were to determine whether the magnitude of abdominal fat change differed by diabetes status in men and women and to identify the predictors of change in abdominal fat distribution with exercise.

RESULTS

Overall, participants (mean age 61±6 years; 45% women) significantly improved peak oxygen uptake by 15% (p<0.01) and reduced weight by 2% (p<0.01). No change in SAT was observed after training. The reduction in VAT following exercise was attenuated in participants with T2DM (-3%) compared with participants who were non-T2DM (-18%, p<0.001 for the difference in change). The magnitude of VAT loss was associated with a decrease in body weight (r=0.50, p<0.001). After adjustment for weight change using regression analysis, diabetes status remained an independent predictor of the change in VAT.

CONCLUSIONS

Although participants with and without T2DM attained an exercise training effect as evidenced by increased fitness, VAT was unchanged in T2DM compared to those without T2DM, suggesting that these individuals may be resistant to this important benefit of exercise. The strategies for reducing cardiovascular disease risk in T2DM may be most effective when they include a weight loss component.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov Registry NCT00212303.

High- and moderate-intensity aerobic exercise and excess post-exercise oxygen consumption in men with metabolic syndrome

Physical activity is central in prevention and treatment of metabolic syndrome. High-intensity aerobic exercise can induce larger energy expenditure per unit of time compared with moderate-intensity exercise. Furthermore, it may induce larger energy expenditure at post-exercise recovery. The aim of this study is to compare the excess post-exercise oxygen consumption (EPOC) in three different aerobic exercise sessions in men with metabolic syndrome. Seven men (age: 56.7 ± 10.8) with metabolic syndrome participated in this crossover study. The sessions consisted of one aerobic interval (1-AIT), four aerobic intervals (4-AIT), and 47-min continuous moderate exercise (CME) on separate days, with at least 48 h between each test day. Resting metabolic rate (RMR) was measured pre-exercise and used as baseline value. EPOC was measured until baseline metabolic rate was re-established. An increase in O2 uptake lasting for 70.4 ± 24.8 min (4-AIT), 35.9 ± 17.3 min (1-AIT), and 45.6 ± 17.3 min (CME) was observed. EPOC were 2.9 ± 1.7 L O2 (4-AIT), 1.3 ±  .1 L O2 (1-AIT), and 1.4 ± 1.1 L O2 (CME). There were significant differences (P < 0.001) between 4-AIT, CME, and 1-AIT. Total EPOC was highest after 4-AIT. These data suggest that exercise intensity has a significant positive effect on EPOC in men with metabolic syndrome.

The role of exercise and physical activity in weight loss and maintenance

This review explores the role of physical activity (PA) and exercise training (ET) in the prevention of weight gain, initial weight loss, weight maintenance, and the obesity paradox. In particular, we will focus the discussion on the expected initial weight loss from different ET programs, and explore intensity/volume relationships. Based on the present literature, unless the overall volume of aerobic ET is very high, clinically significant weight loss is unlikely to occur. Also, ET also has an important role in weight regain after initial weight loss. Overall, aerobic ET programs consistent with public health recommendations may promote up to modest weight loss (~2 kg), however the weight loss on an individual level is highly heterogeneous. Clinicians should educate their patients on reasonable expectations of weight loss based on their physical activity program and emphasize that numerous health benefits occur from PA programs in the absence of weight loss.

Appetite, energy intake, and PYY3–36 responses to energy-matched continuous exercise and submaximal high-intensity exercise

High-intensity intermittent exercise induces physiological adaptations similar to energy-matched continuous exercise, but the comparative appetite and energy balance responses are unknown. Twelve healthy males (mean ± SD: age, 22 ± 3 years; body mass index, 23.7 ± 3.0 kg·m−2; maximum oxygen uptake, 52.4 ± 7.1 mL·kg−1·min−1) completed three 8 h trials (control, steady-state exercise (SSE), high-intensity intermittent exercise (HIIE)) separated by 1 week. Trials commenced upon completion of a standardized breakfast. Exercise was performed from hour 2 to hour 3. In SSE, 60 min of cycling at 59.5% ± 1.6% of maximum oxygen uptake was performed. In HIIE, ten 4-min cycling intervals were completed at 85.8% ± 4.0% of maximum oxygen uptake, with a 2-min rest between each interval. A standardized lunch and an ad libitum afternoon meal were provided at hours 3.75 and 7, respectively. Appetite ratings and peptide YY3–36 concentrations were measured throughout each trial. Appetite was acutely suppressed during exercise, but more so during HIIE (p < 0.05). Peptide YY3–36 concentrations increased significantly upon cessation of exercise in SSE (p = 0.002), but were highest in the hours after exercise in HIIE (p = 0.05). Exercise energy expenditure was not different between HIIE and SSE (p = 0.649), but perceived exertion was higher in HIIE (p < 0.0005). Ad libitum energy intake did not differ between trials (p = 0.833). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in the SSE and HIIE trials than in the control trial (control, 4759 ± 1268 kJ; SSE, 2362 ± 1224 kJ; HIIE, 2523 ± 1402 kJ; p < 0.0005). An acute bout of energy-matched continuous exercise and HIIE were equally effective at inducing an energy deficit without stimulating compensatory increases in appetite.

Efficiency of a free-living physical activity promotion program following diet modification for fat loss in Japanese obese men

The aim of the current study was to examine the efficiency of a free-living physical activity promotion (PAP) program following a diet modification program for fat loss. Fifty obese men, aged 51.4±7.0 y, received a 6-mo regimen consisting of 2 phases. Weekly 90-min free-living PAP sessions were provided for 3 mo immediately after a 3-mo diet modification phase. Fat mass (FM) was measured at baseline and at months 3 and 6 using dual energy X-ray absorptiometry. The time spent in moderate-vigorous physical activity (MVPA) was monitored by a validated single-axis accelerometer. The total energy intake of all participants was assessed at baseline and during weeks 9 and 10 of both the diet modification and PAP programs. The change (Δ) in FM was -1.4±1.9 kg (p<0.05) during the PAP program after the diet modification program (-4.3±2.9 kg, p<0.01). Although there was no significant relationship between ΔFM and ΔMVPA during the PAP phase (p=0.11), MVPA was significantly increased during the PAP phase (+76.0±146.5 min/wk, p<0.01). However, a significant correlation was observed between energy intake/weight and MVPA during the PAP program (r=0.39). Our results suggest that the magnitude of expected FM loss induced by an increase in PA may be suppressed as a result of increased energy intake, even during a PAP program after a diet modification program.

The effect of exercise on the cardiovascular risk factors constituting the metabolic syndrome: a meta-analysis of controlled trials

Background

Numerous meta-analyses have investigated the effect of exercise in different populations and for single cardiovascular risk factors, but none have specifically focused on the metabolic syndrome (MetS) patients and the concomitant effect of exercise on all associated cardiovascular risk factors.

Objective

The aim of this article was to perform a systematic review with a meta-analysis of randomized and clinical controlled trials (RCTs, CTs) investigating the effect of exercise on cardiovascular risk factors in patients with the MetS.

Methods

RCTs and CTs ≥4 weeks investigating the effect of exercise in healthy adults with the MetS and published in a peer-reviewed journal up to November 2011 were included. Primary outcome measures were changes in waist circumference (WC), systolic and diastolic blood pressure, high-density lipoprotein cholesterol (HDL-C), triglycerides and fasting plasma glucose. Peak oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\dot{{V}}\text{O}}_{{ 2 {\text{peak}}}} $$\end{document}) was a secondary outcome. Random and fixed-effect models were used for analyses and data are reported as means and 95% confidence intervals (CIs).

Results

Seven trials were included, involving nine study groups and 206 participants (128 in exercise group and 78 in control group). Significant mean reductions in WC −3.4 (95% CI −4.9, −1.8) cm, blood pressure −7.1 (95% CI −9.03, −5.2)/−5.2 (95% CI −6.2, −4.1) mmHg and a significant mean increase in HDL-C +0.06 (95% CI +0.03, +0.09) mmol/L were observed after dynamic endurance training. Mean plasma glucose levels −0.31 (95% CI −0.64, 0.01; p = 0.06) mmol/L and triglycerides −0.05 (95% CI −0.20, 0.09; p = 0.47) mmol/L remained statistically unaltered. In addition, a significant mean improvement in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\dot{{V}}\text{O}}_{{ 2 {\text{peak}}}} $$\end{document} of +5.9 (95% CI +3.03, +8.7) mL/kg/min or 19.3% was found.

Conclusions

Our results suggest that dynamic endurance training has a favourable effect on most of the cardiovascular risk factors associated with the MetS. However, in the search for training programmes that optimally improve total cardiovascular risk, further research is warranted, including studies on the effects of resistance training and combined resistance and endurance training.

Interaction of physical trainings and coffee intakes in fuel utilization during exercise in rats

This study investigates the impact of exercises, coffee intakes, and physical trainings on fuel utilization in rats. Ninety-six rats were fed a control diet with either water (C) or coffee (CF; 0.12 g freeze-dried instant coffee/100 g body weight/d). Additionally, the animals go through physical training (TC and TCF) or no training (NTC and NTCF) for 4 weeks. For physical training, animals have to exercise on treadmills for 30 minutes (5 d per week, 15° incline, 0.5-0.8 km/h). At the end of week 4, the animals in each group were subdivided into three exercise groups: before exercise (BE), during exercise (DE), and after exercise (AE). The DE rats exercised on treadmills for 1 hour immediately before being sacrificed. Hemoglobin, hematocrit, glucose, glycogen, protein, triglyceride (TG), and free fatty acid (FFA) levels in the plasma, liver, and skeletal muscle of the rats were compared accordingly. Organ weights were also measured. Coffee-training interaction had a significant impact on heart weight, visceral fat, hemoglobin, hematocrit, liver glycogen in DE and AE, and liver triglyceride in DE and AE. Exercise (meaning exercised on a treadmill for 1 hour immediately before being sacrificed) training interaction was significant in liver glycogen, muscle glycogen in control diet and control diet with coffee, FFA and muscle TG levels at control diet with coffee group. Exercise-coffee interactions significantly influenced the FFA with no training groups. Exercise-coffee-training interaction significantly effects on FFA, Liver TG and Muscle TG. Coffee intakes can increase lipolysis during exercising but coffee consumptions delay the recovery of liver glycogen levels in trained rats after exercising. Coffee intakes can increase lipolysis during exercising but coffee consumptions delay the recovery of liver glycogen levels in trained rats after exercising. Coffee can be an effective ergogenic aid during exercise for physically trained rats.

Associations between accelerometer-derived physical activity and regional adiposity in young men and women

OBJECTIVE

Empirical evidence supports an inverse relationship between physical activity (PA) and adiposity, but studies using detailed measures of both are scarce. The relationship between regional adiposity and accelerometer-derived PA in men and women are described.

DESIGN AND METHODS

Cross-sectional analysis included 253 participants from a weight loss study limited to ages 20-45 years and BMI 25-39.9 kg m(-2) . PA data were collected with accelerometers and expressed as total accelerometer counts and average amount of time per day accumulated in different intensity levels [sedentary, light-, and moderate-to-vigorous intensity PA (MVPA)]. Accumulation of time spent above 100 counts was expressed as total active time. Computed tomography (CT) was used to measure abdominal and adipose tissue (AT). Multivariate linear regression analyses were used to assess the relationship between regional adiposity (dependent variable) and the various PA levels (independent variable), and were executed separately for men and women, adjusting for wear time, age, race, education, and BMI.

RESULTS

Among males, light activity was inversely associated with total AT (β = -0.19; P = 0.02) as well as visceral AT (VAT) (β = -0.30; P = 0.03). Among females sedentary time was positively associated with VAT (β = 0.11; P = 0.04) and total active time was inversely associated with VAT (β = -0.12; P = 0.04).

CONCLUSIONS

Findings from this study suggest that PA intensity level may influence regional adiposity differently in men and women. Additional research is needed in larger samples to clarify the difference in these associations by sex, create recommendations for the frequency, duration and intensity of PA needed to target fat deposits, and determine if these recommendations should differ by sex.

Low- and high-volume of intensive endurance training significantly improves maximal oxygen uptake after 10-weeks of training in healthy men

Regular exercise training improves maximal oxygen uptake (VO_2max), but the optimal intensity and volume necessary to obtain maximal benefit remains to be defined. A growing body of evidence suggests that exercise training with low-volume but high-intensity may be a time-efficient means to achieve health benefits. In the present study, we measured changes in VO_2max and traditional cardiovascular risk factors after a 10 wk. training protocol that involved three weekly high-intensity interval sessions. One group followed a protocol which consisted of 4×4 min at 90% of maximal heart rate (HR_max) interspersed with 3 min active recovery at 70% HR_max (4-AIT), the other group performed a single bout protocol that consisted of 1×4 min at 90% HR_max (1-AIT). Twenty-six inactive but otherwise healthy overweight men (BMI: 25–30, age: 35–45 y) were randomized to either 1-AIT (n = 11) or 4-AIT (n = 13). After training, VO_2max increased by 10% (∼5.0 mL⋅kg⁻¹⋅min⁻¹) and 13% (∼6.5 mL⋅kg⁻¹⋅min⁻¹) after 1-AIT and 4-AIT, respectively (group difference, p = 0.08). Oxygen cost during running at a sub-maximal workload was reduced by 14% and 13% after 1-AIT and 4-AIT, respectively. Systolic blood pressure decreased by 7.1 and 2.6 mmHg after 1-AIT and 4-AIT respectively, while diastolic pressure decreased by 7.7 and 6.1 mmHg (group difference, p = 0.84). Both groups had a similar ∼5% decrease in fasting glucose. Body fat, total cholesterol, LDL-cholesterol, and ox-LDL cholesterol only were significantly reduced after 4-AIT. Our data suggest that a single bout of AIT performed three times per week may be a time-efficient strategy to improve VO_2max and reduce blood pressure and fasting glucose in previously inactive but otherwise healthy middle-aged individuals. The 1-AIT type of exercise training may be readily implemented as part of activities of daily living and could easily be translated into programs designed to improve public health.

Trial Registration

ClinicalTrials.govNCT00839579

Association of weight-adjusted body fat and fat distribution with bone mineral density in middle-aged chinese adults: a cross-sectional study

Background

Although it is well established that a higher body weight is protective against osteoporosis, the effects of body fat and fat distribution on bone mineral density (BMD) after adjustment for body weight remains uncertain.

Objective

To examine the relationship between body fat and fat distribution and BMD beyond its weight-bearing effect in middle-aged Chinese adults.

Method

The study had a community-based cross-sectional design and involved 1,767 women and 698 men aged 50–75 years. The BMD of the lumbar spine, total hip, and whole body, and the fat mass (FM) and percentage fat mass (%FM) of the total body and segments of the body were measured by dual-energy X-ray absorptiometry. General information on the participants was collected using structured questionnaire interviews.

Result

After adjusting for potential confounders, an analysis of covariance showed the weight-adjusted (WA-) total FM (or %FM) to be negatively associated with BMD in all of the studied sites (P<0.05) in both women and men. The unfavorable effects of WA-total FM were generally more substantial in men than in women, and the whole body was the most sensitive site related to FM, followed by the total hip and the lumbar spine, in both genders. The mean BMD of the lumbar spine, total hip, and whole body was 3.93%, 3.01%, and 3.65% (in women) and 5.02%, 5.57%, 6.03% (in men) lower in the highest quartile (vs. lowest quartile) according to the WA-total FM (all p<0.05). Similar results were noted among the groups for WA-total FM%. In women, abdominal fat had the most unfavorable association with BMD, whereas in men it was limb fat.

Conclusion

FM (or %FM) is inversely associated with BMD beyond its weight-bearing effect. Abdominal fat in women and limb fat in men seems to have the greatest effect on BMD.

Short bouts of anaerobic exercise increase non-esterified fatty acids release in obesity

PURPOSE

It is demonstrated that aerobic exercise plays an important role in weight loss programs for obesity by increasing 24 h metabolic rate. While aerobic exercise can result in health and fitness benefits in obese subjects, also independently of weight loss, not completely clear are the effects of bouts of hard exercise on metabolic outcomes. The aim of this study was to test the hypothesis that short-term aerobic activity with anaerobic bouts might result in a greater improvement in the management of obesity than aerobic activity alone.

METHODS

We studied 16 obese subjects (eight men) during a progressive cycloergometric test up to exhaustion, before and after 4 weeks of two different training schedules (6 days/week). Insulin and glycaemia, non-esterified fatty acids (NEFA) and lactic acid were sampled. Group A (eight subjects, four men) performed an aerobic cycle workout; Group B (eight subjects, four men) performed a 25 min aerobic workout followed by 5 min of anaerobic workout. All the subjects maintained their individual eating habits.

RESULTS

The post-training test showed a decrease in AUCs NEFA in Group A (p < 0.05) and an increase in Group B (p < 0.05), together with an increase in lactic acid in Group A and a decrease in Group B (p < 0.01). β-cell function (HOMA2-B) revealed a reduction only in Group A (p < 0.05). Group B achieved a greatest reduction in body fat mass than Group A (p < 0.05).

CONCLUSIONS

Aerobic plus anaerobic training seem to produce a greater response in lipid metabolism and not significant modifications in glucose indexes; then, in training prescription for obesity, we might suggest at starting weight loss program aerobic with short bouts of anaerobic training to reduce fat mass and subsequently a prolonged aerobic training alone to ameliorate the metabolic profile.

Body fat responses to a 1-year combined exercise training program in male coronary artery disease patients

OBJECTIVE

To analyze the body fat (BF) content and distribution modifications in coronary artery disease (CAD) patients in response to a 1-year combined aerobic and resistance exercise training (CET) program.

DESIGN AND METHODS

We followed two groups of CAD male patients for 12 months. One group consisted of 17 subjects (57 ± 12 years) who engaged in a CET program (CET group) and the other was a age-matched control group of 10 subjects (58 ± 11 years). BF content and distribution were measured through dual energy X-ray absorptiometry (DXA) at baseline and follow-up.

RESULTS

We found no differences on body mass and BMI between baseline and end of follow-up in both groups but, in CET group, we found significant reductions in all analyzed BF depots, including total BF (21.60 ± 6.00 vs. 20.32 ± 5.89 kg, P < 0.01), % total BF (27.8 ± 5.5 vs. 26.4 ± 5.4%, P < 0.05), trunk fat (12.54 ± 3.99 vs. 11.77 ± 4.01 kg, P < 0.05), % trunk fat (31.1 ± 6.9 and 29.2 ± 7.1%, P < 0.05), appendicular fat (8.22 ± 2.08 vs. 7.72 ± 2.037 kg, P < 0.01), % appendicular fat (25.7 ± 4.9 and 24.5 ± 4.9%, P < 0.05), and abdominal fat (2.95 ± 1.06 vs. 2.75 ± 1.10 kg, P < 0.05). Control group showed significant increase in appendicular fat (7.63 ± 1.92 vs. 8.10 ± 2.12 kg, P < 0.05).

CONCLUSIONS

These results confirm the positive effect of CET on body composition of CAD patients, despite no changes in body mass or BMI. In this study, we observed no alterations on BF distribution meaning similar rate of fat loss in all analyzed BF depots. These results also alert for the limitations of BMI for tracking body composition changes.

Effects of intensity of aerobics on body composition and blood lipid profile in obese/overweight females

BACKGROUND

Obesity is a threat to the health of modern urban citizens, especially women. Aerobic is an effect of exercise which rapidly is developing among urban women. This study was designed to examine the effects of light and moderate aerobic intensity on body composition and serum lipid profile in obese/overweight women living in Isfahan.

METHODS

Forty-five middle-aged obese/overweight volunteer women (25-40 years, and body mass index (BMI) ≥25 to 30 kg/m(2)) were randomly assigned into three groups: 1. Light aerobics [45-50% heart rate reserve maximum (HRRmax)], 2. Moderate aerobics (70-75% HRRmax), 3. No exercise training (control). Training program lasted for 10 weeks and included three sessions of 60 minutes aerobics per week. The intensity of aerobics was controlled by monitoring heart rate. Body composition was measured using skin fold thickness method. Serum lipid was measured.

RESULTS

Both light and moderate aerobics significantly improved weight (P < 0.000), fat percent (P < 0.045), BMI (P < 0.000), fat weight (P < 0/031), lean body weight (P < 0.02), waist-to-hip ratio (WHR) (P < 0.000), High-density lipoprotein (HDL) (P < 0.000).

CONCLUSIONS

Our findings showed that both light and moderate aerobics improved body composition and serum lipid profile in obese/overweight women. Our findings support the application of aerobics for obese/overweight women. Initially, they can start with light programs and proceed to more intense programs.

Moderate to vigorous physical activity and weight outcomes: does every minute count?

PURPOSE

The purpose of this study was to test if moderate to vigorous physical activity (MVPA) in less than the recommended ≥10-minute bouts related to weight outcomes.

DESIGN

Secondary data analysis.

SETTING

Random sample from the U.S. civilian noninstitutionalized population included in the National Health and Nutrition Examination Survey (NHANES).

PARTICIPANTS

A total of 4511 adults aged 18 to 64 years from the 2003-2006 NHANES.

METHOD

Clinically measured body mass index (BMI) and overweight/obese status were regressed on accelerometer measures of minutes per day in higher-intensity long bouts (≥10 minutes, ≥2020 accelerometer counts per minute [cpm]), higher-intensity short bouts (<10 minutes, ≥2020 cpm), lower-intensity long bouts (≥10 minutes, 760-2019 cpm), and lower-intensity short bouts (<10 minutes, 760-2019 cpm). Socioeconomic and demographic characteristics were controlled.

RESULTS

Both higher-intensity short bouts and long bouts of PA related to lower BMI and risk of overweight/obesity. Neither lower-intensity short bouts nor long bouts related to BMI or risk of overweight/obesity.

CONCLUSION

The current ≥10-minute MVPA bouts guideline was based on health benefits other than weight outcomes. Our findings showed that for weight gain prevention, accumulated higher-intensity PA bouts of <10 minutes are highly beneficial, supporting the public health promotion message that "every minute counts."

The effect of exercise on visceral adipose tissue in overweight adults: a systematic review and meta-analysis

Excessive visceral adipose tissue appears to trigger a cascade of metabolic disturbances that seem to coexist with ectopic fat storage in muscle, liver, heart and the ß-cell. Therefore, the reduction of visceral adipose tissue potentially plays a pivotal role in the treatment of the metabolic syndrome. The purpose of this systematic review and meta-analysis is to describe the overall effect of exercise on visceral adipose tissue and to provide an overview of the effect of different exercise regimes, without caloric restriction, on visceral adipose tissue in obese persons. A systematic literature search was performed according to the PRISMA statement for reporting systematic reviews and meta-analyses. The initial search resulted in 87 articles after removing duplicates. After screening on title, abstract and full-text 15 articles (totalling 852 subjects) fulfilled the a priori inclusion criteria. The quality of each eligible study was assessed in duplicate with “The Critical Review Form for Quantitative Studies”. Using random-effects weights, the standardized mean difference (Hedge's g) of the change in visceral adipose tissue was −0.497 with a 95% confidence interval of −0.655 to −0.340. The Z-value was −6.183 and the p-value (two tailed) was <0.001. A subgroup analysis was performed based on gender, type of training and intensity. Aerobic training of moderate or high intensity has the highest potential to reduce visceral adipose tissue in overweight males and females. These results suggest that an aerobic exercise program, without hypocaloric diet, can show beneficial effects to reduce visceral adipose tissue with more than 30 cm² (on CT analysis) in women and more than 40 cm² in men, even after 12 weeks.

Feasibility and preliminary efficacy of high intensity interval training in type 2 diabetes

AIMS

To compare the feasibility of high intensity interval exercise (HI-IE) versus moderate intensity continuous exercise (MI-CE) in patients with type 2 diabetes (T2D), and to investigate the preliminary efficacy of HI-IE and MI-CE for improving glycated hemoglobin A1c (HbA1c) and body composition.

METHODS

Individuals with T2D were recruited and randomly assigned to HI-IE and MI-CE. Exercise training was performed 5 days per week for 12 weeks. Recruitment, retention, adherence, feeling states and self-efficacy were analyzed for feasibility. Changes in HbA1c and percent body fat from baseline were investigated at 12 weeks to determine the preliminary efficacy.

RESULTS

Of 126 participants showing interest to join the study, 15 individuals were randomized and completed the program. No participants dropped out from the study after enrollment. Adherence rates were high and did not differ between HI-IE and MI-CE (p>0.05; >97.2% of the eligible exercise sessions for both groups). Feeling states and self-efficacy did not differ between the groups. Percent trunk fat decreased in both HI-IE and MI-CE (p=0.007 and 0.085, respectively). Total percent body fat, percent leg fat, and subcutaneous fat width were significantly reduced in both groups (p<0.05), whereas HbA1c did not change from baseline (p>0.05). The degree of improvement was similar between the interventions (p>0.05).

CONCLUSION

In individuals with T2D, implementing a 12-week structured HI-IE training can be as feasible as MI-CE training. Both interventions are equally effective in lowering total body fat but have little impact on HbA1c in relatively well controlled participants with T2D.

The effects of free-living interval-walking training on glycemic control, body composition, and physical fitness in type 2 diabetic patients: a randomized, controlled trial

OBJECTIVE

To evaluate the feasibility of free-living walking training in type 2 diabetic patients and to investigate the effects of interval-walking training versus continuous-walking training upon physical fitness, body composition, and glycemic control.

RESEARCH DESIGN AND METHODS

Subjects with type 2 diabetes were randomized to a control (n = 8), continuous-walking (n = 12), or interval-walking group (n = 12). Training groups were prescribed five sessions per week (60 min/session) and were controlled with an accelerometer and a heart-rate monitor. Continuous walkers performed all training at moderate intensity, whereas interval walkers alternated 3-min repetitions at low and high intensity. Before and after the 4-month intervention, the following variables were measured: VO(2)max, body composition, and glycemic control (fasting glucose, HbA(1c), oral glucose tolerance test, and continuous glucose monitoring [CGM]).

RESULTS

Training adherence was high (89 ± 4%), and training energy expenditure and mean intensity were comparable. VO(2)max increased 16.1 ± 3.7% in the interval-walking group (P < 0.05), whereas no changes were observed in the continuous-walking or control group. Body mass and adiposity (fat mass and visceral fat) decreased in the interval-walking group only (P < 0.05). Glycemic control (elevated mean CGM glucose levels and increased fasting insulin) worsened in the control group (P < 0.05), whereas mean (P = 0.05) and maximum (P < 0.05) CGM glucose levels decreased in the interval-walking group. The continuous walkers showed no changes in glycemic control.

CONCLUSIONS

Free-living walking training is feasible in type 2 diabetic patients. Continuous walking offsets the deterioration in glycemia seen in the control group, and interval walking is superior to energy expenditure-matched continuous walking for improving physical fitness, body composition, and glycemic control.

Physical activity, cardiorespiratory fitness, and exercise training in primary and secondary coronary prevention

Substantial data have established that higher levels of physical activity (PA), participating in exercise training (ET), and higher overall cardiorespiratory fitness (CRF) provide considerable protection in the primary and secondary prevention of coronary heart disease (CHD). This review surveys data from epidemiological and prospective ET studies supporting the favorable impact of PA, ET, and CRF in primary CHD prevention. Clearly, cardiac rehabilitation and ET (CRET) programs have been underutilized for patients with CHD, particularly considering the effect of CRET on CHD risk factors, including CRF, obesity indices, fat distribution, plasma lipids, inflammation, and psychological distress, as well as overall morbidity and mortality. These data strongly support the routine referral of patients with CHD to CRET programs and that patients should be vigorously encouraged to attend CRET following major CHD events.

Effects of high-intensity exercise training on body composition, abdominal fat loss, and cardiorespiratory fitness in middle-aged Korean females

The primary purpose of this study was to investigate the effects of high-intensity exercise training under relatively equal energy expenditure on whole body fat and abdominal fat loss, and cardiorespiratory fitness. Twenty-two untrained middle-aged Korean females were randomized into one of the following groups: control, low-intensity training group (LI), and high-intensity training group (HI). Subjects completed 14 weeks of training at 50% maximal oxygen consumption (LI) or 70% maximal oxygen consumption (HI) with the volume of exercise equated relative to kilograms of body weight. Weekly exercise volumes were 13.5 METs⋅h/week for the first 4 weeks, 18 METs⋅h/week for next 5 weeks, and 22.5 METs⋅h/week for the final 5 weeks. Data were analyzed using 2-way repeated measures ANOVA with post hoc test, using Bonferroni's correction. HI showed significant reductions in fat mass (p < 0.05), total abdominal fat (p < 0.01), and subcutaneous abdominal fat (p < 0.01). LI reduced total abdominal fat (p < 0.05), but there were no other significant changes found in the control or LI groups. Maximal oxygen consumption was enhanced in both HI and LI with no significant group difference. High-density lipoprotein cholesterol increased significantly in HI (p < 0.05). IL-6, C-reactive protein, TNF-α, and other blood lipids were unaltered following training. Results indicate that high-intensity exercise training is more beneficial in whole body and abdominal fat loss; however, cardiorespiratory enhancement shows a dose-response relationship with weekly exercise volume. It is suggested that 14 weeks of aerobic exercise training at either high- or low-intensity is not sufficient enough to induce changes in levels of inflammatory proteins.

Obesidade abdominal e fatores associados em adolescentes: comparação de duas regiões brasileiras diferentes economicamente

OBJETIVO: Verificar as diferenças e similaridades na prevalência e fatores associados à obesidade abdominal em adolescentes de duas áreas brasileiras distintas economicamente. SUJEITOS E MÉTODOS: Estudo transversal com 1.065 escolares de 14 a 17 anos, sendo 601 do Meio Oeste Catarinense, SC, e 464 do Norte de Minas, MG. Identificou-se a obesidade abdominal por meio da circunferência da cintura. As variáveis independentes foram as sociodemográficas, adiposidade corporal e comportamento relacionado à atividade física. RESULTADOS: A prevalência de obesidade abdominal foi maior no Meio Oeste catarinense (6,3%; IC95%: 4,4-8,3) em comparação ao Norte de Minas (2,1%; IC95%: 0,8-3,5). Os meninos e o excesso de adiposidade corporal foram fatores associados à obesidade abdominal em ambas as regiões. CONCLUSÃO: Embora existam diferenças na prevalência de obesidade abdominal em adolescentes de duas áreas distintas economicamente, os fatores associados à obesidade foram semelhantes.

Effects of aerobic exercise intensity on abdominal and thigh adipose tissue and skeletal muscle attenuation in overweight women with type 2 diabetes mellitus

BACKGROUND

We investigated the effects of exercise intensity on abdominal and mid-thigh adipose tissue, attenuation of skeletal muscle, and insulin sensitivity in overweight women with type 2 diabetes mellitus (T2DM).

METHODS

Twenty-eight patients were randomly assigned to control (CG, n=12), moderate intensity exercise (MEG, n=8), or vigorous intensity exercise (VEG, n=8) group. Subjects in both exercise groups completed a 12-week exercise program (MEG, 3.6 to 5.2 METs; VEG, ≥5.2 METs) that was monitored by accelerometers. We assessed body mass index (BMI), total fat area (TFA), visceral fat area (VFA), subcutaneous fat area (SFA), mid-thigh intramuscular adipose tissue (TIMAT), total skeletal muscle (TTM), low density skeletal muscle (TLDM), and normal density skeletal muscle (TNDM) using computed tomography, and measured insulin sensitivity with an insulin tolerance test (K(ITT)), before and after the intervention.

RESULTS

At baseline, the mean age was 53.8±7.9 years, duration of diabetes was 3.8±2.3 years, and BMI was 26.6±2.6 kg/m(2). After 12 weeks, the percent change (%C) in BMI, TIMAT, and TLDM were not different among three groups. However, %C in TFA and VFA were significantly reduced in MEG compared to CG (P=0.026 and P=0.008, respectively). %C SFA was significantly reduced in VEG compared to CG (P=0.038) and %C TTM, TNDM, and K(ITT) were significantly increased in VEG compared to the CG (P=0.044, P=0.007, and P=0.016, respectively).

CONCLUSION

Although there was no difference in the change in BMI among groups, TFA and VFA were more reduced in MEG, and only VEG increased TTM, TNDM, and insulin sensitivity compared to CG.

Lifestyle intervention improves fitness independent of metformin in obese adolescents

PURPOSE

Obesity in adolescence increases the risk for early adult cardiovascular disease. We recently showed that 6 months of diet, exercise, and metformin resulted in reductions in adiposity and that diet/exercise alone reduced proinflammatory factors and intrahepatic fat in pubertal children with uncomplicated obesity. The purpose of the present study was to determine whether changes in cardiorespiratory fitness (CRF) after 6 months of structured diet and exercise (DE) or DE plus metformin are related to the previously observed changes in adiposity, markers of inflammation, and intrahepatic fat.

METHODS

Sixteen obese pubertal adolescents between the ages of 10 and 17 were randomized into a structured lifestyle program consisting of DE or DE plus metformin. Subjects performed aerobic and resistance exercise 3 d·wk⁻¹, 30 min per session. Cycle ergometer maximal oxygen consumption (V˙O2max), body composition, blood markers (glucose, insulin, homeostatic model assessment-insulin resistance, interleukin-6, hsCRP), and intrahepatic fat were measured at baseline and 6 months.

RESULTS

In the cohort, as whole-body weight decreased by 4.0% (P = 0.009), body mass index decreased by 4.9% (P = 0.003), percent body fat decreased by 8.8% (P < 0.001), and V˙O2max improved in 10 of 16 subjects. The addition of metformin provided no further effect on body composition, CRF, or inflammatory factors. More favorable changes in adiposity, adiponectin, and a trend toward blood glucose and interleukin-6 concentrations (P = 0.07) were observed in subjects who increased V˙O2max at 6 months (n = 10) compared with no change in these variables in those who did not improve V˙O2max.

CONCLUSIONS

Metformin did not provide benefits above lifestyle modification for improving CRF in obese adolescents. Improvements in V˙O2max seem to be associated with more favorable metabolic outcomes.

Physical activity and exercise in the regulation of human adipose tissue physiology

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.

Lifestyle factors and 5-year abdominal fat accumulation in a minority cohort: the IRAS Family Study

The objective of this study was to examine whether lifestyle factors were associated with 5-year change in abdominal fat measured by computed tomography (CT) in the Insulin Resistance and Atherosclerosis (IRAS) Family Study. We obtained abdominal CT scans at baseline and at 5 years, from African Americans (AA) (N = 339) and Hispanic Americans (N = 775), aged 18-81 years. Visceral (VAT) and subcutaneous (SAT) adipose tissue was measured at the L4/L5 vertebral level. Physical activity was documented by self-report of vigorous activity and a 1-year recall instrument. Dietary intake was assessed at follow-up using a semi-quantitative food frequency questionnaire referencing the previous year. Generalized linear models, accounting for family structure, were used to assess the associations between percent change in fat accumulation and smoking, physical activity, total calories, polyunsaturated, monounsaturated, protein, and saturated fat intake, percent of calories from sweets, and soluble and insoluble fiber. Soluble fiber intake and participation in vigorous activity were inversely related to change in VAT, independent of change in BMI. For each 10 g increase in soluble fiber, rate of VAT accumulation decreased by 3.7% (P = 0.01). Soluble fiber was not associated with change in SAT (0.2%, P = 0.82). Moderately active participants had a 7.4% decrease in rate of VAT accumulation and a 3.6% decrease in rate of SAT accumulation versus less active participants (P = 0.003 and P = 0.01, respectively). Total energy expenditure was also inversely associated with accumulation of VAT. Soluble fiber intake and increased physical activity were related to decreased VAT accumulation over 5 years.

Physical activity for obese individuals: a systematic review of effects on chronic disease risk factors

The purpose of this review was to determine the effectiveness of physical activity in improving chronic disease risk factors in obese individuals. A systematic review was conducted to identify randomized physical activity intervention studies reporting changes in risk factors among obese individuals published prior to March 2010. Studies included in the review were randomized trials of at least 10 weeks in duration, with a sample mean body mass index ≥ 30 kg/m(2) at baseline, and reporting a relevant risk factor (blood pressure, blood lipids, glucose/insulin or C-reactive protein). Forty-four studies met the inclusion criteria for this review. Overall, physical activity had no more than a modest effect on chronic disease risk factors in obese individuals. There was great heterogeneity in responses of risk factors across studies. In many studies it was difficult to determine the effect of physical activity, independent of changes in body mass consequent to the intervention. Obese individuals should be encouraged to undertake physical activity following general recommendations for weight loss and health. The degree to which physical activity is effective at lowering risk factor levels among high-risk obese individuals is not known.

A systematic review and meta-analysis of the effect of aerobic vs. resistance exercise training on visceral fat

It is increasingly recognized that the location of excess adiposity, particularly increased deposition of visceral adipose tissue (VAT), is important when determining the adverse health effects of overweight and obesity. Exercise therapy is an integral component of obesity management, but the most potent exercise prescription for VAT benefit is unclear. We aimed to evaluate the independent and synergistic effects of aerobic exercise (AEx) and progressive resistance training (PRT) and to directly compare the efficacy of AEx and PRT for beneficial VAT modulation. A systematic review and meta-analysis was performed to assess the efficacy of exercise interventions on VAT content/volume in overweight and obese adults. Relevant databases were searched to November 2010. Included studies were randomized controlled designs in which AEx or PRT in isolation or combination were employed for 4 weeks or more in adult humans, where computed tomography (CT) or magnetic resonance imaging (MRI) was used for quantification of VAT pre- and post-intervention. Of the 12196 studies from the initial search, 35 were included. After removal of outliers, there was a significant pooled effect size (ES) for the comparison between AEx therapy and control (-0.33, 95% CI: -0.52 to -0.14; P < 0.01) but not for the comparison between PRT therapy and control (0.09, 95% CI: -0.17 to -0.36; P = 0.49). Of the available nine studies which directly compared AEx with PRT, the pooled ES did not reach statistical significance (ES = 0.23, 95% CI: -0.02 to 0.50; P = 0.07 favouring AEx). The pooled ES did not reach statistical significance for interventions that combined AEx and PRT therapy vs. control (-0.28, 95% CI: -0.69 to 0.14; P = 0.19), for which only seven studies were available. These data suggest that aerobic exercise is central for exercise programmes aimed at reducing VAT, and that aerobic exercise below current recommendations for overweight/obesity management may be sufficient for beneficial VAT modification. Further investigation is needed regarding the efficacy and feasibility of multi-modal training as a means of reducing VAT.

A Cross-Sectional Analysis of the Association between Physical Activity and Visceral Adipose Tissue Accumulation in a Multiethnic Cohort

Higher levels of VAT at the same body size and lower levels of physical activity (PA) have been reported in persons of Chinese and South Asian origin compared to European origin. The purpose of this study was to test the hypothesis that higher levels of VAT in persons of Chinese and South Asian origin versus European origin are associated with lower levels of PA. Chinese, European, and South Asian participants were assessed for sociodemographics, obesity-related measures, anthropometrics, and PA. Bivariate correlations, analysis of covariance, and regression models were used to explore ethnic differences in PA and the role of PA in explaining obesity-related measures. We observed ethnic differences in both body fat distribution and PA. Chinese and South Asians had higher amounts of VAT at a given BMI but lower amounts of moderate PA, vigorous PA, and moderate-to-vigorous PA (MVPA). Furthermore, we found ethnic-specific differences in the associations between body fat distribution and PA with only Europeans showing a consistent negative relationship between body fat distribution and PA. When ethnic differences in PA were taken into account, there were no longer any differences in VAT between the Chinese and European groups, while VAT remained higher in South Asians than Europeans.

The relationship between oxygen uptake reserve and heart rate reserve is affected by intensity and duration during aerobic exercise at constant work rate

The relationship between the percentage of heart rate reserve (%HRR) and percentage of oxygen uptake reserve (%VO2R) has been recommended for prescribing aerobic exercise intensity. However, this relationship was derived from progressive maximal exercise testing data, and the stability of the relationship during prolonged exercise at a constant work rate has not been established. The main aim of this study was to investigate the stability of the %VO2R–%HRR relationship during prolonged treadmill exercise bouts performed at 3 different constant work rates. Twenty-eight men performed 4 exercise tests: (i) a ramp-incremental maximal exercise test to determine maximal heart rate (HRmax) and maximal oxygen uptake (VO2max) and (ii) three 40-min exercise bouts at 60%, 70%, and 80% VO2R. HR and VO2 significantly increased over time and were influenced by exercise intensity (p < 0.001 and p = 0.004, respectively). A 1:1 relationship between %HRR and %VO2R, and between %HRR and %VO2max, was not observed, with mean differences of 8% (t = 5.2, p < 0.001) and 6% (t = 4.8, p < 0.001), respectively. The VO2 values predicted from the ACSM running equation were all significantly higher than the observed VO2 values (p < 0.001 for all comparisons), whereas a difference for HR was observed only for the tenth min of exercise at 80% VO2R (p = 0.041). In conclusion, the main finding of this study was that the %HRR–%VO2R relationship determined by linear regression, obtained from progressive maximal exercise testing, did not apply to prolonged treadmill running performed at 3 work rates.