The effect of physical training on insulin production in obesity

Risk of Metabolic Syndrome and Glucose Homeostasis Among Childhood and Young Adult Acute Lymphoblastic Leukemia Survivors: Part of the ALL-STAR Study

BACKGROUND

Metabolic syndrome (MetS), a risk factor for early cardiovascular morbidity and mortality, is seen in up to 34% of survivors of childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

We performed a Danish, national cross-sectional study of ALL survivors (aged 1-45 years at diagnosis) treated according to the NOPHO ALL2008 protocol, examined at least 1 year after treatment cessation. The study included non-cancer community controls, matched on sex and age. We explored the prevalence and components of the MetS criteria (hyperglycemia, hypertension, increased waist circumference (WC), and dyslipidemia) and glucose homeostasis (insulin and C-peptide).

RESULTS

We included 366 survivors of ALL (participation rate 84%) and 368 controls. Median age (IQR) at follow-up examination was 14.1 (10.8-21.8) years, and follow-up time after the ALL diagnosis was 6.9 (4.7-9.1). The prevalence of MetS in survivors was 7.6% and in controls 3.8 % (p = 0.039). The increased MetS prevalence was driven by ALL patients undergoing total body irradiation (TBI), and age and body mass index (BMI) percentile ≥95 at diagnosis (p ≤ 0.01). The MetS prevalence in non-TBI patients did not differ from controls (p = 0.43), but non-TBI patients more often fulfilled the MetS criteria WC and/or elevated high-density lipoprotein (p < 0.03). Survivors had higher serum insulin and C-peptide than controls (p < 0.01).

CONCLUSIONS

ALL survivors have an increased risk of MetS compared with controls, essentially driven by the patients treated with TBI. The MetS frequency in non-TBI patients is equal to controls, but non-TBI patients more often have one or two components of Mets. ALL survivors seem slightly more insulin-resistant than controls.

Effects of Vitamin E Intake and Voluntary Wheel Running on Whole-Body and Skeletal Muscle Metabolism in Ovariectomized Mice

Background/Objectives: Ovariectomized rodents experience metabolic dysfunction in whole-body and skeletal muscle. A disrupted balance between oxidative stress and antioxidants might exacerbate metabolic dysfunction in ovariectomized rodents. Dietary antioxidants, such as vitamin E intake, before or during exercise would be beneficial by mitigating the exercise-induced increase in oxidative stress in ovariectomized rodents. The purpose of the current study was to investigate the potential effect of vitamin E intake combined with voluntary exercise on whole-body and skeletal muscle metabolism in ovariectomized mice. Methods: This study used C57BL/6J wild-type female mice (n = 40, 8 weeks old), which were randomly assigned into sham (SHM), ovariectomy (OVX), ovariectomy with exercise (OVXVE), ovariectomy with vitamin E (OVXV), ovariectomy with exercise and vitamin E (OVXVE) groups. Body composition, resting metabolic rate, glucose tolerance, skeletal muscle mitochondrial function, and protein contents were assessed using dual-energy x-ray absorptiometry, indirect calorimetry, glucose tolerance test, O2K OROBOROS, and Western blot, respectively. Results: The combined treatment of vitamin E and voluntary wheel running did not show a beneficial effect on whole-body metabolism such as fat mass, energy expenditure, and glucose tolerance. However, independent of exercise intervention, vitamin E intake enhanced mitochondrial function, Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC1-a), and adenosine monophosphate-activated protein kinase (AMPK) levels and also reduced oxidative stress in the skeletal muscles of ovariectomized mice. Specifically, in the soleus muscle, vitamin E intake enhanced mitochondrial function and PGC1-a content (p < 0.05). In the gastrocnemius muscle, vitamin E intake enhanced PGC1-a and AMPK levels and reduced a marker of oxidative stress (p < 0.05). Conclusions: Vitamin E, as a potent antioxidant, may play a crucial role in maintaining skeletal muscle health in ovariectomized mice. More studies are necessary to investigate whether this finding is applicable to women.

A single bout of physical exercise improves 1-hour post-load plasma glucose in healthy young adults

PURPOSE

Physical exercise is a key component in the treatment of type 2 diabetes and plays an important role in maintaining a healthy glucose metabolism even in healthy subjects. To date, no studies have investigated the effect of a single bout of aerobic physical exercise on glucose metabolism in young, moderately active, healthy adults.

METHODS

We performed an OGTT 7 days before and 24 h after a single bout of physical exercise, to evaluate 1-hour post-load plasma glucose and surrogate indexes of insulin sensitivity and insulin secretion.

RESULTS

Glucose levels were significantly reduced after exercise at baseline and one hour after glucose load; similarly, insulin was significantly lower 1 h after glucose load. We found a significant increase in the Matsuda index, confirmed by OGIS index, QUICKI index, and by significant reduction in HOMA-IR. Conversely, we observed a trend to increase in HOMA-B.

CONCLUSION

This is the first study to evaluate the effect of a single bout of exercise on 1-hour glucose levels following OGTT. We found a significant reduction in 1-hour glucose levels following OGTT together with an increased insulin sensitivity. A single 30-minute bout of aerobic exercise also seemed to improve the insulin secretion pattern. Modifications in beta cell secretory capacity during exercise are likely secondary to an improvement in insulin action in insulin dependent tissues.

A free-living, walking-based, exercise programme, with exercise timed relative to breakfast, to improve metabolic health in people living with overweight and obesity: A feasibility study

Optimising the timing of food intake relative to exercise may maximise the effectiveness of free-living exercise programmes on improvements in glycaemic control and cardio-metabolic health. This study aimed to assess the feasibility of a free-living, walking-based exercise programme and determine whether undertaking each exercise session before or after breakfast would most benefit longer-term metabolic health. Thirty-four people living with obesity (43±12 y, BMI 35.1±5.1 kg.m-2) undertook a 12-week walking-based programme, consisting of two continuous (30-60 min at 50% HRmax) and two interval exercise sessions per week (30-60 min, alternating 3 min at 85% HRmax and 3 min at 50% HRmax). Participants were allocated to exercise before (FASTED) or after (FED) breakfast (n = 17 per group). Feasibility (acceptability, adherence and compliance) to the exercise intervention were assessed, as well as changes in anthropometric variables, 24-hour continuous glucose monitoring, serum biochemistry including HbA1c, lipid profile and liver transaminases. Exercise adherence (FASTED: 93±4%, FED: 95±5%) and compliance (FASTED: 85±10%, FED: 88±10%) was high in both groups, and participants described exercise monitoring, programme structure and support as facilitators to this. Body mass, BMI, waist-to-hip ratio and HbA1c decreased similarly between groups (all P<0.01). However, serum ALT concentrations decreased after FASTED (-16± -14%; P = 0.001), but not FED training (-2 ± -4%; P = 0.720). We demonstrate that a free-living walking-based exercise programme, with exercise timed relative to breakfast can achieve high adherence and compliance and improve some anthropometric variables and HbA1c. Whether FASTED exercise can elicit greater improvements in liver health requires further investigation.

Intermittent and Periodic Fasting, Hormones, and Cancer Prevention

The restriction of proteins, amino acids or sugars can have profound effects on the levels of hormones and factors including growth hormone, IGF-1 and insulin. In turn, these can regulate intracellular signaling pathways as well as cellular damage and aging, but also multisystem regeneration. Both intermittent (IF) and periodic fasting (PF) have been shown to have both acute and long-term effects on these hormones. Here, we review the effects of nutrients and fasting on hormones and genes established to affect aging and cancer. We describe the link between dietary interventions and genetic pathways affecting the levels of these hormones and focus on the mechanisms responsible for the cancer preventive effects. We propose that IF and PF can reduce tumor incidence both by delaying aging and preventing DNA damage and immunosenescence and also by killing damaged, pre-cancerous and cancer cells.

History of Strength Training Research in Man: An Inventory and Quantitative Overview of Studies Published in English Between 1894 and 1979

ABSTRACT

Nuzzo, JL. History of strength training research in man: an inventory and quantitative overview of studies published in English between 1894 and 1979. J Strength Cond Res 35(5): 1425-1448, 2021-Limited scholarship exists on the history of strength training research. The current review advances existing qualitative and biographical work by inventorying all experimental studies and case reports published before 1980 on the effects of ≥1 week of strength training on human health and function. Data on authors, journals, citations, study samples, training interventions, study outcomes, and study themes were extracted and summarized. Three hundred thirty-nine strength training studies were published between 1894 and 1979. Studies included 14,575 subjects, with 10,350 undergoing strength training. Subjects were usually healthy (81.1% of articles), university students (51.0%), or aged 18-65 years (86.7%). Men comprised 70.0% of subjects. Interventions typically involved isoinertial only (64.6%) or isometric only (35.4%) training. Upper-body interventions were more common (35.4%) than lower-body interventions (27.4%). Duration and frequency of training were typically 4-8 weeks (55.3%) and 3 days per week (39.2%), respectively. Isometric maximal voluntary contractions (54.0%) and one repetition maximum (20.4%) were the most common muscle strength tests. Other common outcomes included limb girths (20.9%) and muscle endurance (19.5%). Common research themes were physiology (54.3%), physical fitness (28.9%), and injury/rehabilitation (20.4%). The 339 studies have been cited 21,996 times. Moritani and deVries' 1979 article on time course of neuromuscular adaptations is the most highly cited (1,815 citations). DeLorme (5 articles and 772 citations), Hellebrandt (4 articles and 402 citations), Rasch (9 articles and 318 citations), and Berger (12 articles and 1,293 citations) made the largest contributions. Research Quarterly published the most articles (27.4%). The history of strength training research is discussed in the context of the results.

Prepregnancy Fat Free Mass and Associations to Glucose Metabolism Before and During Pregnancy

OBJECTIVE

Our aim was to quantify the individual contribution of prepregnancy (PP) fat-free mass (FFM), expressed as [PP-FFM index (PP-FFMI) = FFM (kg)/height (m2)], on markers of glucose homeostasis before and during pregnancy.

METHODS

Body composition was assessed in 43 women before pregnancy using air-displacement plethysmography. Blood was drawn at PP and gestational weeks ∼8 and 30. Relationships between body composition (independent) variables and glucose homeostasis (dependent) variables were assessed using adjusted correlations and simple and multiple linear regression analyses.

RESULTS

PP-FFMI was the strongest predictor of plasma insulin concentration [squared partial correlation (Pr2) = 17, P = 0.007] and homeostasis model assessment of insulin resistance (HOMA2-IR) (Pr2 = 16, P = 0.010). At gestation week 30, PP-FFMI and gestational weight gain (GWG) were the strongest predictors of insulin concentration (PP-FFMI: Pr2 = 20, P = 0.010; GWG: Pr2 = 12, P = 0.052) and HOMA2-IR (PP-FFMI: Pr2 = 19, P = 0.012; GWG: Pr2 = 13, P = 0.045). After accounting for PP fat mass index (PP-FMI), PP-FFMI and GWG were independently associated with first-phase insulin response (PP-FFMI: Pr2 = 20, P = 0.009; GWG: Pr2 = 15, P = 0.025) and second-phase insulin response (PP-FFMI: Pr2 = 19, P = 0.011; GWG: Pr2 = 17, P = 0.016). PP-FMI was the strongest predictor of an oral glucose tolerance test‒derived estimated metabolic clearance rate of glucose (PP-FMI: Pr2 = 14, P = 0.037) and estimated insulin sensitivity index (PP-FMI: Pr2 = 13, P = 0.047).

CONCLUSIONS

PP-FFMI was a predictor of markers of glucose homeostasis before and during pregnancy. Studies assessing the effect of skeletal muscle quality on metabolic regulation during pregnancy are warranted.

A pilot study of metabolic fitness effects of weight-supported walking in women with obesity

Background

This is an exploratory pilot study of novel technology enabling people with mobility disability to walk with minimal effort, in the “sedentary range”. The study’s premise is that impairment of the leading physical activity of daily living, walking, is a major contributor to a dysmetabolic state driving many prevalent “civilization diseases” associated with insulin resistance.

Methods

We explore within-subject changes in standard oral glucose tolerance (OGT) tests including metabotropic molecules after 22 twice-weekly, 30-minute bouts of weight-supported light-moderate physical activity in 16 non-diabetic obese, otherwise healthy, reproductive-age, volunteer women walking on an “anti-gravity” lower-body positive pressure (LBPP) treadmill.

Results

Subjects had reference base-line fasting plasma glucose and triglycerides (TG) but 2-hr OGT insulin levels of 467 ± 276 pmol • liter^-1 (mean± S.D.) indicating nascent insulin resistance, compared to post-study 308 ± 179 (p = 0.002). Fasting TG decreased from 0.80 ± 0.30 mmol • liter^-1 to 0.71 ± 0.25 (p = 0.03). Concomitantly plasma total ghrelin decreased from 69.6 ± 41.6 pmol • liter^-1 to 56.0 ± 41.3 (p = 0.008). There were no statistically significant changes in body weight or any correlations between weight change and cardiometabolic markers. However, there were robust positive correlations between changes among different classes of peptides including C-reactive protein–Interleukin 6, leptin–adiponectin, β-endorphin–oxytocin and orexin A (r ² = 0.48–0.88).

Conclusion

We conclude that brief, low-dose physical activity, walking on an anti-gravity LBPP treadmill may improve cardiometabolic risk, exhibiting favorable changes in neuro-regulatory peptides without weight loss in people with problems walking.

Determinants of gestational diabetes mellitus: a case-control study

BACKGROUND

Gestational diabetes mellitus (GDM) is glucose intolerance first recognized during pregnancy. The objective of this study was to identify the determinant factors of GDM.

METHODS

An unmatched case-control study was conducted. Descriptive statistics were used to describe the profile of study participants and binary logistic regression was used to identify the determinants of GDM.

RESULTS

GDM was associated with history of abortion (AOR 5.05 [95% CI: 2.65-9.63]), family history of diabetes mellitus (AOR 8.63 [95% CI: 5.19-14.35]), chronic hypertension (AOR 4.63 [95% CI: 1.27-16.86]), dietary diversification score (AOR 2.96 [95% CI: 2-4.46]), regular physical exercise (AOR 0.03 [95% CI: 0.01-0.04]), history of infertility (AOR 6.19 [95%CI: 1.86-20.16]), history of Caesarean section (AOR 3.24 [95% CI: 1.58-6.63]), previous history of GDM (AOR 8.21 [95% CI: 3.18-21.24]), previous history of intrauterine fetal death (AOR 3.96 [95% CI: 1.56-10.04]), literacy (AOR 0.6 [95% CI: 0.43-0.85]), body mass index (AOR 2.96 [95% CI: 2.08-4.2]), parity (AOR 1.78 [95% CI: 1.3-2.49]).

CONCLUSIONS

Regular physical exercise should be used as the main tool in preventing GDM.

Health at Every Size

It would be difficult to overstate the urgency that U.S. government and health officials have placed on the dangers posed by obesity. Given the increasing numbers of individuals being diagnosed as overweight and obese and the emphasis on the contribution of weight to health and disease, it is critical that all health professionals examine the validity of the claims being made. A thorough examination of the research literature does not support the claims that overweight and obesity are major causes of premature mortality, excess fat is pathological and a direct cause of disease, and weight loss is practical and beneficial to health for most individuals. The literature also does not provide any significant evidence-based support for current approaches to weight management. In fact, it suggests that these approaches may likely be doing more harm than good.

Effects of oatmeal and corn flakes cereal breakfasts on satiety, gastric emptying, glucose, and appetite-related hormones

OBJECTIVE

The extent to which different types of breakfasts affect appetite and food intake is unclear. To assess the satiety effects of a high-fiber cereal, we compared oatmeal, isocaloric corn flakes, and water.

SUBJECTS/METHODS

Thirty-six subjects (18 lean, 18 overweight) were assigned to three conditions in a randomized sequence on different days. Ratings of hunger and fullness were obtained concurrently with blood samples for measuring concentrations of glucose, insulin, glucagon, leptin, and acetaminophen (gastric emptying tracer). Appetite was assessed by calculating the area under the curve (AUC) for fullness and hunger, and by measuring food intake of an ad libitum lunch meal at 180 min.

RESULTS

Lunch meal intake was lowest after consuming oatmeal (p < 0.00001), which was lower for overweight subjects than lean subjects (p = 0.007). Fullness AUC was greatest (p = 0.00001), and hunger AUC lowest (p < 0.001) after consuming oatmeal. At 180 min, blood glucose was lowest after the corn flakes (p = 0.0001). Insulin AUC was greater for both cereals than water (p < 0.00001). Leptin AUC and glucagon AUC values did not differ between conditions. Acetaminophen concentrations peaked latest after consuming oatmeal (p = 0.046), reflecting slower gastric emptying.

CONCLUSIONS

Satiety was greater and ad libitum test meal intake lower after consuming oatmeal than after corn flakes, especially in the overweight subjects.

Ventilatory responses at peak exercise in endurance-trained obese adults

BACKGROUND

Alterations in respiratory mechanics predispose healthy obese individuals to low lung volume breathing, which places them at risk of developing expiratory flow limitation (EFL). The high ventilatory demand in endurance-trained obese adults further increases their risk of developing EFL and increases their work of breathing. The objective of this study was to investigate the prevalence and magnitude of EFL in fit obese (FO) adults via measurements of breathing mechanics and ventilatory dynamics during exercise.

METHODS

Ten (seven women and three men) FO (mean ± SD, 38 ± 5 years, 38% ± 5% body fat) and 10 (seven women and three men) control obese (CO) (38 ± 5 years, 39% ± 5% body fat) subjects underwent hydrostatic weighing, pulmonary function testing, cycle exercise testing, and the determination of the oxygen cost of breathing during eucapnic voluntary hyperpnea.

RESULTS

There were no differences in functional residual capacity (43% ± 6% vs 40% ± 9% total lung capacity [TLC]), residual volume (21% ± 4% vs 21% ± 4% TLC), or FVC (111% ± 13% vs 104% ± 15% predicted) between FO and CO subjects, respectively. FO subjects had higher FEV1 (111% ± 13% vs 99% ± 11% predicted), TLC (106% ± 14% vs 94% ± 7% predicted), peak expiratory flow (123% ± 14% vs 106% ± 13% predicted), and maximal voluntary ventilation (128% ± 15% vs 106% ± 13% predicted) than did CO subjects. Peak oxygen uptake (129% ± 16% vs 86% ± 15% predicted), minute ventilation (128 ± 35 L/min vs 92 ± 25 L/min), and work rate (229 ± 54 W vs 166 ± 55 W) were higher in FO subjects. Mean inspiratory (4.65 ± 1.09 L/s vs 3.06 ± 1.21 L/s) and expiratory (4.15 ± 0.95 L/s vs 2.98 ± 0.76 L/s) flows were greater in FO subjects, which yielded a greater breathing frequency (51 ± 8 breaths/min vs 41 ± 10 breaths/min) at peak exercise in FO subjects. Mechanical ventilatory constraints in FO subjects were similar to those in CO subjects despite the greater ventilatory demand in FO subjects.

CONCLUSION

FO individuals achieve high ventilations by increasing breathing frequency, matching the elevated metabolic demand associated with high fitness. They do this without developing meaningful ventilatory constraints. Therefore, endurance-trained obese individuals with higher lung function are not limited by breathing mechanics during peak exercise, which may allow healthy obese adults to participate in vigorous exercise training.

AMPK, insulin resistance, and the metabolic syndrome

Insulin resistance (IR) and hyperinsulinemia are hallmarks of the metabolic syndrome, as are central adiposity, dyslipidemia, and a predisposition to type 2 diabetes, atherosclerotic cardiovascular disease, hypertension, and certain cancers. Regular exercise and calorie restriction have long been known to increase insulin sensitivity and decrease the prevalence of these disorders. The subsequent identification of AMP-activated protein kinase (AMPK) and its activation by exercise and fuel deprivation have led to studies of the effects of AMPK on both IR and metabolic syndrome-related diseases. In this review, we evaluate this body of literature, with special emphasis on the hypothesis that dysregulation of AMPK is both a pathogenic factor for these disorders in humans and a target for their prevention and therapy.

Review of the key results from the Swedish Obese Subjects (SOS) trial - a prospective controlled intervention study of bariatric surgery

Obesity is a risk factor for diabetes, cardiovascular disease events, cancer and overall mortality. Weight loss may protect against these conditions, but robust evidence for this has been lacking. The Swedish Obese Subjects (SOS) study is the first long-term, prospective, controlled trial to provide information on the effects of bariatric surgery on the incidence of these objective endpoints. The SOS study involved 2010 obese subjects who underwent bariatric surgery [gastric bypass (13%), banding (19%) and vertical banded gastroplasty (68%)] and 2037 contemporaneously matched obese control subjects receiving usual care. The age of participants was 37-60 years and body mass index (BMI) was ≥34 kg m(-2) in men and ≥38 kg m(-2) in women. Here, we review the key SOS study results published between 2004 and 2012. Follow-up periods varied from 10 to 20 years in different reports. The mean changes in body weight after 2, 10, 15 and 20 years were -23%, -17%, -16% and -18% in the surgery group and 0%, 1%, -1% and -1% in the control group respectively. Compared with usual care, bariatric surgery was associated with a long-term reduction in overall mortality (primary endpoint) [adjusted hazard ratio (HR) = 0.71, 95% confidence interval (CI) 0.54-0.92; P = 0.01] and decreased incidences of diabetes (adjusted HR=0.17; P < 0.001), myocardial infarction (adjusted HR = 0.71; P = 0.02), stroke (adjusted HR=0.66; P = 0.008) and cancer (women: adjusted HR = 0.58; P = 0.0008; men: n.s.]. The diabetes remission rate was increased severalfold at 2 years [adjusted odds ratio (OR) = 8.42; P < 0.001] and 10 years (adjusted OR = 3.45; P < 0.001). Whereas high insulin and/or high glucose at baseline predicted favourable treatment effects, high baseline BMI did not, indicating that current selection criteria for bariatric surgery need to be revised.

Obesity: a disease or a biological adaptation? An update

Obesity is characterized by the accumulation of excess body fat and can be conceptualized as the physical manifestation of chronic energy excess. An important challenge of today's world is that our so-called obesogenic environment is conducive to the consumption of energy and unfavourable to the expenditure of energy. The modern, computer-dependent, sleep-deprived, physically inactive humans live chronically stressed in a society of food abundance. From a physiological standpoint, the excess weight gain observed in prone individuals is perceived as a normal consequence to a changed environment rather than a pathological process. In other words, weight gain is a sign of our contemporary way of living or a 'collateral damage' in the physiological struggle against modernity. Additionally, substantial body fat loss can complicate appetite control, decrease energy expenditure to a greater extent than predicted, increase the proneness to hypoglycaemia and its related risk towards depressive symptoms, increase the plasma and tissue levels of persistent organic pollutants that promote hormone disruption and metabolic complications, all of which are adaptations that can increase the risk of weight regain. In contrast, body fat gain generally provides the opposite adaptations, emphasizing that obesity may realistically be perceived as an a priori biological adaptation for most individuals. Accordingly, prevention and treatment strategies for obesity should ideally target the main drivers or root causes of body fat gain in order to be able to improve the health of the population.

Exercise training, genetics and type 2 diabetes-related phenotypes

Type 2 diabetes mellitus (T2DM) is at virtually pandemic levels world-wide. Diabetes has been referred to as 'a geneticist's nightmare'. However, dramatic advances in our understanding of the genetics of T2DM have occurred in the past 5 years. While endurance exercise training and increased habitual physical activity levels have consistently been shown to improve or be associated with improved T2DM-related phenotypes, there is substantial interindividual variation in these responses. There is some evidence that T2DM-related phenotype responses to exercise training are heritable, indicating that they might have a genetic basis. Genome-wide linkage studies have not identified specific chromosomal loci that could account for these differences, and no genome-wide association studies have been performed relative to T2DM-related phenotype responses to exercise training. From candidate gene studies, there are relatively strong and replicated data supporting a role for the PPARγ Pro12Ala variant in the interindividual differences in T2DM-related phenotype responses to training. This is a potentially important candidate locus because it affects T2DM susceptibility, has high biological plausibility and is the target for the primary pharmaceutical method for treating T2DM. Is it time to conduct a hypothesis-driven large-scale exercise training intervention trial based on PPARγ Pro12Ala genotype with T2DM-related phenotypes as the primary outcome measures, while also assessing potential mechanistic changes in skeletal muscle and adipose tissue? Or would it be more appropriate to propose a smaller trial to address the specific skeletal muscle and adipose tissue mechanisms affected by the interaction between the PPARγ Pro12Ala genotype and exercise training?

Change of energy expenditure from physical activity is the most powerful determinant of improved insulin sensitivity in overweight patients with coronary artery disease participating in an intensive lifestyle modification program

The objective was to evaluate the determinants of change (Δ) in insulin sensitivity in overweight coronary artery disease male patients without diabetes after an intensive lifestyle intervention. All patients received nutritional counseling and performed 4 months of exercise training (ET) according to 1 of 2 protocols: aerobic ET (65%-70% of peak aerobic capacity [VO(2)]) 25 to 40 minutes 3 times a week (n = 30) or walking (50%-60% of peak VO(2)) 45 to 60 minutes at least 5 times a week (n = 30). Data from participants of both ET groups were pooled, and post-intensive lifestyle intervention results were compared with baseline data. The primary outcome was Δ insulin sensitivity (m-value) assessed by the criterion standard technique, the euglycemic-hyperinsulinemic clamp. Changes in weight, body mass index, total and percentage fat mass (by dual-energy x-ray absorptiometry scan), waist circumference, total abdominal and visceral fat (by computed tomographic scan), high-sensitivity C-reactive protein, peak VO(2), daily energy intake, and physical activity energy expenditure (PAEE) (by doubly labeled water technique) were also assessed. Daily energy intake decreased by 335 kcal, and PAEE increased by 482 kcal/d (all P < .0001). The mean weight loss was 6.4 kg, and the mean improvement in m-value was 1.6 mg/kg fat-free mass per minute. Univariate determinants of Δ m-value were low baseline PAEE, walking protocol, Δ weight, Δ body mass index, Δ total and percentage fat mass, Δ waist circumference, Δ total abdominal and visceral fat, and Δ PAEE (all P < .05). In multivariate analysis, the only significant determinant of Δ m-value was Δ PAEE (P < .02). In this analysis, the most powerful determinant of improved insulin sensitivity in overweight coronary artery disease patients is the change in PAEE.

Obesity but not overweight is associated with increased mortality risk

The association between body mass index (BMI) and survival has been described in various populations. However, the results remain controversial and information from low-prevalence Western countries is sparse. Our aim was to examine this association and its public health impact in Switzerland, a country with internationally low mortality rate and obesity prevalence. We included 9,853 men and women aged 25-74 years who participated in the Swiss MONICA (MONItoring of trends and determinants in CArdiovscular disease) study (1983-1992) and could be followed up for survival until 2008 by using anonymous record linkage. Cox regression models were used to calculate mortality hazard ratios (HRs) and to estimate excess deaths. Independent variables were age, sex, survey wave, diet, physical activity, smoking, educational class. After adjustment for age and sex the association between BMI and all-cause mortality was J shaped (non-smokers) or U shaped (smokers). Compared to BMI 18.5-24.9, among those with BMI ≥ 30 (obesity) HR for all-cause mortality was 1.41 (95% confidence interval: 1.23-1.62), for cardiovascular disease (CVD) 2.05 (1.60-2.62), for cancer 1.29 (1.04-1.60). Further adjustment attenuated the obesity-mortality relationship but the associations remained statistically significant. No significant increase was found for overweight (BMI 25-29.9). Between 4 and 6.5% of all deaths, 8.8-13.7% of CVD deaths and 2.4-3.9% of cancer deaths could be attributed to obesity. Obesity, but not overweight was associated with excess mortality, mainly because of an increased risk of death from CVD and cancer. Public health interventions should focus on preventing normal- and overweight persons from becoming obese.

Exercise and diet, independent of weight loss, improve cardiometabolic risk profile in overweight and obese individuals

Diet and/or exercise are routinely advised as methods for weight loss in overweight/obese individuals, particularly those who are at high risk for cardiovascular disease and type 2 diabetes mellitus. However, physical activity and structured exercise programs rarely result in significant loss of body weight or body fat, and weight-loss diets have extraordinarily high recidivism rates. Despite only modest effects on body weight, exercise and ad libitum nutrient-dense diets for overweight/obese individuals have many health benefits, including skeletal muscle adaptations that improve fat and glucose metabolism, and insulin action; enhance endothelial function; have favorable changes in blood lipids, lipoproteins, and hemostatic factors; and reduce blood pressure, postprandial lipemia and glycemia, and proinflammatory markers. These lifestyle-induced adaptations occur independently of changes in body weight or body fat. Thus, overweight/obese men and women who are at increased risk for cardiovascular disease and type 2 diabetes as a result of sedentary lifestyle, poor diet, and excess body weight should be encouraged to engage in regular physical activity and improve their diet, regardless of whether the healthier lifestyle leads to weight loss.

Weight science: evaluating the evidence for a paradigm shift

Current guidelines recommend that "overweight" and "obese" individuals lose weight through engaging in lifestyle modification involving diet, exercise and other behavior change. This approach reliably induces short term weight loss, but the majority of individuals are unable to maintain weight loss over the long term and do not achieve the putative benefits of improved morbidity and mortality. Concern has arisen that this weight focus is not only ineffective at producing thinner, healthier bodies, but may also have unintended consequences, contributing to food and body preoccupation, repeated cycles of weight loss and regain, distraction from other personal health goals and wider health determinants, reduced self-esteem, eating disorders, other health decrement, and weight stigmatization and discrimination. This concern has drawn increased attention to the ethical implications of recommending treatment that may be ineffective or damaging. A growing trans-disciplinary movement called Health at Every Size (HAES) challenges the value of promoting weight loss and dieting behavior and argues for a shift in focus to weight-neutral outcomes. Randomized controlled clinical trials indicate that a HAES approach is associated with statistically and clinically relevant improvements in physiological measures (e.g., blood pressure, blood lipids), health behaviors (e.g., eating and activity habits, dietary quality), and psychosocial outcomes (such as self-esteem and body image), and that HAES achieves these health outcomes more successfully than weight loss treatment and without the contraindications associated with a weight focus. This paper evaluates the evidence and rationale that justifies shifting the health care paradigm from a conventional weight focus to HAES.

Exercise maintains euglycemia in association with decreased activation of c-Jun NH2-terminal kinase and serine phosphorylation of IRS-1 in the liver of ZDF rats

Stress-activated systems and oxidative stress are involved in insulin resistance, which, along with beta-cell failure, contribute to the development of type 2 diabetes mellitus (T2DM). Exercise improves insulin resistance and glucose tolerance, and these adaptations may, in part, be related to reductions in inflammation and oxidative stress. We investigated circulating and tissue-specific markers of inflammation and oxidative stress and insulin-signaling pathways in a rodent model of T2DM, the Zucker diabetic fatty rat, with and without voluntary exercise. At 5 wk of age, Zucker diabetic fatty rats (n = 8-9/group) were divided into basal (B), voluntary exercise (E), and sedentary control (S) groups. B rats were euthanized at 6 wk of age, and S and E rats were euthanized 10 wk later. E rats ran approximately 5 km/day, which improved insulin sensitivity and maintained fed and fasted glucose levels and glucose tolerance. Ten weeks of exercise also decreased whole body markers of inflammation and oxidative stress in plasma and liver, including lowered circulating IL-6, haptoglobin, and malondialdehyde levels, hepatic protein oxidation, and phosphorylated JNK, the latter indicating decreased JNK activity. Hepatic phosphoenolpyruvate carboxykinase levels and Ser(307)-phosphorylated insulin receptor substrate-1 were also reduced in E compared with S rats. In summary, we show that, in a rodent model of T2DM, voluntary exercise decreases circulating markers of inflammation and oxidative stress and lowers hepatic JNK activation and Ser(307)-phosphorylated insulin receptor substrate-1. These changes in oxidative stress markers and inflammation are associated with decreased hyperglycemia and insulin resistance and reduced expression of the main gluconeogenic enzyme phosphoenolpyruvate carboxykinase.

Novos mecanismos pelos quais o exercício físico melhora a resistência à insulina no músculo esquelético

O prejuízo no transporte de glicose estimulada por insulina no músculo constitui um defeito crucial para o estabelecimento da intolerância à glicose e do diabetes tipo 2. Por outro lado, é notório o conhecimento de que tanto o exercício aeróbio agudo quanto o crônico podem ter efeitos benéficos na ação da insulina em estados de resistência à insulina. No entanto, pouco se sabe sobre os efeitos moleculares pós-exercício sobre a sinalização da insulina no músculo esquelético. Assim, esta revisãoapresenta novos entendimentos sobre os mecanismos por meio dos quais o exercício agudo restaura a sensibilidade à insulina, com destaque ao importante papel que proteínas inflamatórias e a S-nitrosação possuem sobre a regulação de proteínas da via de sinalização da insulina no músculo esquelético.

Type I diabetes and physical exercise

Metabolic effects of physical exercise in type I diabetes are reviewed. Physical training leads to an increased insulin sensitivity but does not seem to influence the metabolic control. However, the metabolic control is of importance for the exercise results. Patients in a good control do not differ from normal individuals concerning working capacity, recovery after hypoglycemia and hormonal balance. Furthermore, abnormalities in the blood glucose homeostasis during exercise in type I diabetes are discussed as well as potential beneficial effects of physical training in the prevention of cardiovascular disease.

The effect of acute and chronic exercise on thyroid hormones in obesity

Thyroid hormones were measured before, during and after acute exercise (60 min) or physical training (3 months) in obese women. Thyroid stimulating hormone concentration increased during acute work and decreased immediately after. No changes were seen during the two following days. An increase was seen after ten days as well as after three months of physical training. Thyroxine concentrations showed no changes. 3,5,3'-Triiodothyronine decreased slightly immediately after acute exercise, and after three months of physical training, 3,3',5'-triiodothyronine (reverse triiodothyronine) increased slowly during and after acute exercise. A negative correlation was found between changes in fasting insulin and thyroxine and a positive correlation between changes in blood pressure and triiodothyronine after training. Lack of agreement in previous reports is probably due to methodological differences such as methods more or less susceptible to fatty acid interference, and thyroid hormones changing differently during acute work and before and after physical training. The duration of the study may also be of importance, even 3 months possibly being too short for attaining equilibrium in thyroid homeostasis.

Glucose intolerance and insulin resistance accompany immobilization

Physical activity is known to increase glucose tolerance and insulin sensitivity. To examine the influence of physical inactivity on insulin sensitivity, we measured oral glucose tolerance (OGTT) and insulin response to glucose in 18 patients immobilized to bed for six weeks after acute spine fracture. The results were compared to those of nine chronically immobilized spinal cord injury patients and to eight healthy mobile controls. During the first week after trauma both glucose and insulin responses in the OGTT were two- to three-fold above normal (p less than 0.01). The index of insulin resistance (glucose area X insulin area) was seven-fold greater than in healthy controls (p less than 0.001). After three weeks' immobilization insulin resistance had declined by 30-35% (p less than 0.05) being then at the level observed in chronically immobilized subjects. After remobilization the insulin resistance was further decreased but remained still 2.3 times higher than in controls. Thus, trauma causes a manifold increase in insulin resistance, which is reduced but not normalized during the subsequent immobilization and remobilization.

Effects of exercise on glucose tolerance and insulin resistance. Brief review and some preliminary results

With aging, glucose tolerance (GT) declines, plasma insulin concentration increases, and sensitivity to the action of insulin declines. Evidence is accumulating that this decline in glucose tolerance and insulin sensitivity can be prevented by regularly performed vigorous exercise. Preliminary results are presented in this paper showing that prolonged, strenuous and frequent exercise can also completely normalize GT by decreasing resistance to insulin in some patients with mild non insulin dependent diabetes mellitus (NIDDM) and in some individuals with impaired glucose tolerance (IGT). Exercise appears to be effective in normalizing GT only in patients who still have an adequate capacity to secrete insulin, and in whom insulin resistance is the major cause for abnormal GT. The amount of exercise required to normalize GT in such patients appears to be in the range of 25 to 35 km per week of running, or a comparable amount of another form of exercise, performed on a regular basis.

The correlation between metabolic syndrome and prostatic growth in patients with benign prostatic hyperplasia

OBJECTIVES

To evaluate the relationship between metabolic syndrome and annual prostatic growth rates in benign prostatic hyperplasia (BPH) patients.

METHODS

The 78 BPH patients with lower urinary tract symptoms included in this prospective study were divided into two groups according to whether they had a diagnosis of metabolic syndrome. This diagnosis was made according to the most recent consensus report of the National Cholesterol Education Program's Third Adult Treatment Panel. Blood pressure, body weight, body height, and waist and hip circumferences were measured. The body mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Biochemical analyses including serum glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), insulin, and prostate-specific antigen (PSA) were performed. Total prostate (TP) volume and transitional zone (TZ) volume were measured by transrectal ultrasound. Annual TP and TZ growth rates were calculated.

RESULTS

BPH patients with metabolic syndrome (first group) had significantly higher median body weight, BMI, serum glucose, serum triglyceride, and PSA levels but lower serum HDL-C level, compared with BPH patients without metabolic syndrome (second group, p<0.05). Median annual TP growth rate (1.0 ml/yr) and median annual TZ growth rate (1.25 ml/yr) were significantly higher in the first group versus the second group (0.64 ml/yr and 0.93 ml/yr, respectively, p<0.05).

CONCLUSIONS

The present study demonstrates a further increase in prostate growth in BPH patients with metabolic syndrome. Future studies are needed to confirm our results and to explain underlying mechanisms.

Visceral obesity: a "civilization syndrome"

The controversial question of the relationship between obesity and disease has been considerably clearer after the demonstration in several prospective, epidemiological studies that the subgroup of central, visceral obesity is particularly prone to develop cardiovascular disease, stroke, and non-insulin dependent diabetes mellitus. Visceral obesity is associated with multiple central endocrine aberrations. The hypothalamo-adrenal axis is apparently sensitive to stimuli, sex steroid hormone secretion blunted, and hyperandrogenicity is found in women. In addition, there seem to be signs of central dysfunctions in the regulation of hemodynamic factors after stress, and growth hormone secretion appears to be particularly blunted. Several of these endocrine abnormalities are associated with insulin resistance, particularly glycogen synthesis in muscle. Fiber composition with low type I/type II ratio might be secondary to the prevailing hyperinsulinemia, but low capillary density in muscle may well be of importance. In combination with elevated turn-over of free fatty acids (FFA) this will probably provide powerful mechanisms whereby insulin resistance is created. Portal FFA, from the highly lipolytic visceral depots may, in addition, affect hepatic metabolism to induce increased gluconeogenesis, production of very low density lipoproteins as well as to perhaps inhibit clearance of insulin. By these mechanisms a Metabolic Syndrome Visceral adipocytes seem to have a high density of several steroid hormone receptors, directing steroid hormone effects particularly to these depots. The net effect of cortisol is apparently a stimulation of lipid storage, with opposing effects of sex steroid hormones which also facilitate lipid mobilization, regulations most often found at the gene transcription level. Growth hormone inhibits cortisol effects on lipid accumulation, and amplifies the lipid mobilizing effects of steroid hormones. The combined perturbations of hormonal secretions will therefore probably direct triglycerides toward visceral depots. Circulatory and nervous regulatory mechanisms require, however, more attention. The multiple central endocrine and nervous aberrations of visceral obesity suggest neuroendocrine dysregulations, and have features characteristic of the hypothalamic arousal seen after certain types of stress, alcohol intake, and smoking. Such factors can be traced to subjects with visceral fat accumulation. Standardized stress, eliciting a "defeat reaction" in primates is followed by an apparently identical syndrome. This integrated picture of the multiple symptoms of visceral obesity is based on epidemiological, clinical, experimental, cellular, and molecular evidence. The ingredients of positive energy balance, including physical inactivity, stress, smoking, and alcohol consumption are frequent features of modern, urbanized society. Visceral obesity may therefore be an expression of a "Civilization Syndrome."

Physical activity and body functionality: implications for obesity prevention and treatment

Physical activity promotes metabolic adaptations that improve body functionality and contribute to the prevention of some diseases. With respect to energy and fat balance, physical activity facilitates the equilibrium between energy intake and expenditure as well as between fat intake and fat oxidation. When combined with a healthy diet that favors satiety with a reduced energy intake, exercise can induce a substantial mass loss in obese individuals. However, even the impact of an exemplary lifestyle does not seem to have the potential to decrease body mass in obese individuals down to the mass range of lean people. Up to now, we have not been able to induce mass changes exceeding 12%–15% initial body mass in obese male subjects under tolerable exercise and dietary habits, and this moderate success was accompanied by modifications in appetite and energy expenditure susceptible to compromise subsequent mass stability. As described in this paper, many environmental factors can influence energy balance and the ability to lose body fat in response to a healthy diet and (or) physical activity program. Particular attention is given to preliminary data obtained in our laboratory that suggest that knowledge-based work does not favor the same potential mass reducing effects as physical work. In fact, the acute effects of knowledge-based work suggest that this work modality may be rather susceptible to promote a more pronounced positive energy balance compared with what we may expect from a sedentary relaxing activity. This is problematic for obesity prevention in the future since knowledge-based work now represents the main working modality in a context of modernity.

Cardiovascular disease prevalence and risk factors of persons with mental retardation

This paper reviews the recent literature on cardiovascular disease (CVD) prevalence, CVD-related mortality, physiological CVD risk factors, and behavioral CVD risk factors in adults with mental retardation (MR). The literature on the potential influences of modifiable behavioral CVD risk factors and the physiological CVD risk factors are also reviewed. Adults with mild to moderate MR residing in community settings appear to have an elevated disease prevalence, elevated CVD-related mortality, more adverse physiological CVD risk factors, and elevated behavioral risk compared to others with and without MR. Preliminary evidence supports the benefits of participating in the recommended physical activity levels and consuming the recommended diets to reduce the risk for CVD. The lack of large-scale longitudinal or experimental research indicates a gap in the research. The development of research-based, appropriate, primary prevention programs and intervention strategies aimed at lowering the risk for CVD is highly recommended. Programs should focus on educating individuals with MR along with direct care providers and family members on the importance of appropriate dietary concepts, physical activity habits, and regular health screenings by physicians. Programs should be individualized to regional and cultural issues.

Exercise enhances insulin and leptin signaling in the cerebral cortex and hypothalamus during dexamethasone-induced stress in diabetic rats

Exercise and dexamethasone (DEX) are known to have opposite effects on peripheral insulin resistance. However, their effects and mechanism on brain glucose metabolism have been poorly defined. We investigated the modulation of the hypothalamo-pituitary-adrenal (HPA) axis and insulin/leptin signaling associated with glucose utilization in the brains of 90% pancreatectomized diabetic rats, which had been administered two dosages of DEX and exercised for 8 weeks. The data revealed that the administration of a high dose (0.1 mg/kg body weight/day) of DEX (HDEX) attenuated insulin signaling in the cerebral cortex and hypothalamus, whereas exercise potentiated their insulin signaling along with induction of IRS2 expression. In parallel with the modulated signaling, glucose utilization, such as glycogen storage and glycogen synthase activity, was suppressed by DEX in the cortex and hypothalamus, while exercise offset the DEX effects. Despite a decrease in epididymal fat mass, HDEX increased serum leptin levels, possibly due to an activated HPA axis, while exercise suppressed the increment. However, DEX reduced leptin-induced STAT3 phosphorylation in the cortex and hypothalamus, and it increased AMP-activated protein kinase (AMPK) phosphorylation only in the hypothalamus. Exercise reversed the phosphorylation of STAT3 and AMPK which had been modulated by DEX. In conclusion, exercise improves insulin and leptin signaling in the cerebral cortex and hypothalamus of diabetic rats exacerbated with HDEX, contributing to the regulation of body weight and glucose homeostasis.

Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery

BACKGROUND

Weight loss is associated with short-term amelioration and prevention of metabolic and cardiovascular risk, but whether these benefits persist over time is unknown.

METHODS

The prospective, controlled Swedish Obese Subjects Study involved obese subjects who underwent gastric surgery and contemporaneously matched, conventionally treated obese control subjects. We now report follow-up data for subjects (mean age, 48 years; mean body-mass index, 41) who had been enrolled for at least 2 years (4047 subjects) or 10 years (1703 subjects) before the analysis (January 1, 2004). The follow-up rate for laboratory examinations was 86.6 percent at 2 years and 74.5 percent at 10 years.

RESULTS

After two years, the weight had increased by 0.1 percent in the control group and had decreased by 23.4 percent in the surgery group (P<0.001). After 10 years, the weight had increased by 1.6 percent and decreased by 16.1 percent, respectively (P<0.001). Energy intake was lower and the proportion of physically active subjects higher in the surgery group than in the control group throughout the observation period. Two- and 10-year rates of recovery from diabetes, hypertriglyceridemia, low levels of high-density lipoprotein cholesterol, hypertension, and hyperuricemia were more favorable in the surgery group than in the control group, whereas recovery from hypercholesterolemia did not differ between the groups. The surgery group had lower 2- and 10-year incidence rates of diabetes, hypertriglyceridemia, and hyperuricemia than the control group; differences between the groups in the incidence of hypercholesterolemia and hypertension were undetectable.

CONCLUSIONS

As compared with conventional therapy, bariatric surgery appears to be a viable option for the treatment of severe obesity, resulting in long-term weight loss, improved lifestyle, and, except for hypercholesterolemia, amelioration in risk factors that were elevated at baseline.

Independent and additive effects of energy restriction and exercise on glucose and insulin concentrations in sedentary overweight men

BACKGROUND

Overweight and inactivity are associated with impaired glucose tolerance, reduced insulin sensitivity, and diabetes. Few controlled trials have assessed the independent and combined effects of energy restriction and exercise on the prevention of these conditions.

OBJECTIVE

The objective was to evaluate the independent and additive effects of 16 wk of energy restriction and exercise on glucose and insulin concentrations.

DESIGN

Sixty nonsmoking, overweight, sedentary men aged 20-50 y were randomly assigned to either maintain or restrict their energy intake (4186-6279 kJ/d). Within each of these arms, the subjects were further randomly assigned to either a light-intensity (control) or a vigorous-intensity exercise program for 30 min 3 times/wk.

RESULTS

Fifty-one subjects completed the study. Maximal oxygen uptake increased ( approximately 24%; P < 0.001) with vigorous but not with light exercise. Significant weight loss was observed with energy restriction (x: 10.12 kg; 95% CI: 8.02, 12.22 kg; P < 0.001) but not with exercise. Vigorous exercise reduced fasting glucose and glucose and insulin areas under the curve (AUCs) by 13% (P = 0.01) and 20% (P = 0.02), respectively. Exercise effects were independent of weight change. Energy restriction resulted in a 40% reduction in the insulin AUC (P = 0.01). Vigorous exercise and energy restriction were additive in reducing the insulin AUC.

CONCLUSIONS

Energy restriction and vigorous exercise independently and additively reduce glucose and insulin concentrations in response to an oral-glucose-tolerance test. Both of these lifestyle interventions provide a potent strategy that should be an integral part of any program to reduce the risk of impaired glucose tolerance, insulin resistance, and diabetes in overweight and sedentary persons.

Glucose and insulin responses following 16 months of exercise training in overweight adults: the Midwest Exercise Trial

The current study examined the insulin and glucose response during an oral glucose tolerance test (OGTT) in overweight young adults prior to and following exercise training in the Midwest Exercise Trial (MET). Subjects (N = 66) were randomly assigned to non-exercise control (CON; 16 females, 13 males) or exercise (EX; 22 females, 15 males) groups. EX performed supervised and verified exercise on 3 to 5 days per week in 20- to 45-minute sessions at 60% to 75% of heart rate reserve. OGTTs and assessments for body mass, body composition, and maximal oxygen consumption (Vo(2) max) were performed at baseline, and after 9 and 16 months of training. Blood was collected during a 75-g OGTT and analyzed for glucose and insulin concentrations with the total area under the glucose and insulin curves used in the analysis. The EX males had significant decreases from baseline to 9 months in body mass (94.8 +/- 12.5 to 89.2 +/- 9.8 kg) and percent fat (28.3 +/- 4.8 to 24.2 +/- 3.9) with no further changes at 16 months. CON females had significant increases in body mass (78.2 +/- 6.4 to 81.1 +/- 8.1 kg) and percent fat (36.6 +/- 4.2 to 37.8 +/- 4.7) from baseline to 16 months. Vo(2) max increased significantly from baseline to 9 months in the EX males (3.67 +/- 0.62 to 4.36 +/- 0.55 L/min) and EX females (2.53 +/- 0.32 to 2.99 +/- 0.42 L/min). For glucose area under the curve, there were no significant differences between EX or CON across the 16 months of the study. For insulin area under the curve, there was a significant decrease for male EX from baseline to 9 months (12,535 +/- 6,114 to 8,390 +/- 4,231 microU/L/180 min). We conclude that regular exercise in healthy, previously sedentary overweight adult males leads to improvements in Vo(2) max and weight loss and a reduction in the insulin concentration required to dispose of a set glucose load. In females, improvement in Vo(2) max without weight loss does not lead to improvement in insulin sensitivity.

Insulin signalling: effects of prior exercise

After the discovery and clinical use of insulin for treatment of diabetes it became clear that some of the biological effect of insulin was dependent on the circumstances under which it was given. Relevant for this review is the notion that physical activity, in addition to its own direct metabolic effects also markedly affects the ability of insulin to stimulate a range of metabolic processes. More specifically, during and for a prolonged period after, exercise elicits effects on processes such as insulin-induced muscle glucose uptake and glucose metabolism which influence systemic glucose homeostasis. These phenomena are probably responsible for the improvement in glucose homeostasis and metabolic control that typically occurs with exercise in people with insulin resistance and probably contributes to the reduced risk for development of type 2 diabetes in individuals who engage in regular exercise. Here we focus on the influence of a single bout of exercise on the action of insulin on processes such as glucose uptake and glucose storage in skeletal muscle.

Effects of a two-month rehabilitation program on substrate utilization during exercise in obese adolescents

BACKGROUND

We assessed the impact of an exercise and diet program for two weeks in a specialized institute and six weeks at home on body composition and exercise metabolism in obese adolescents.

METHODS

Fourteen obese adolescents took part in the two-week training course and seven continued exercise and diet at home. The substrate crossover point and the maximal fat oxidation point (Lipox max) were determined before and after the program, using indirect calorimetry. Individualized exercise training at Lipox max was programmed over the two months.

RESULTS

At the end of the two-week program, all adolescents showed a decrease in weight (p<0.001). Only the seven subjects who continued exercise training at home showed improved exercise fat use (increased crossover point of 17% +/- 3 (p<0.005) and Lipox max of 12.5% +/- 1.5 (p<0.005)).

CONCLUSION

The teenagers who had performed this targeted regular training for two months exhibit an increase in their ability to oxidize lipids at exercise. This increase is no longer found in those treated by diet alone. The efficiency of this targeted training protocol based on calorimetry for the treatment of teenager obesity will require longer studies on greater samples of subjects.