Cardiorespiratory fitness and metabolic risk factors in obesity

Effects of a 12-week walking intervention on circulating lipid profiles and adipokines in normal weight and abdominal obese female college students

Background/objectives

Regular exercise such as aerobic exercise has been shown to reduce the risk of some diseases such as cardiovascular disease (CVD). However, only few studies have investigated the impact of regular aerobic exercise on non-obese and overweight/obese persons. Therefore, this study was designed to compare the effect of a 12-week 10,000 steps a day walking intervention on the body composition, serum lipids, adipose tissue function, and obesity-associated cardiometabolic risk between normal weight and overweight/obese female college students.

Methods

Ten normal weight (NWCG) and 10 overweight/obese (AOG) individuals were recruited in this study. Both groups performed a regular 10,000 steps a day walk for 12 weeks. Their blood pressure, body mass index, waist-to-hip ratio, and blood lipid profiles were evaluated. Moreover, serum leptin and adiponectin levels were measured using an enzyme-linked immunosorbent assay.

Results

Our results revealed that triglyceride (TG), TG/high-density lipoprotein cholesterol (HDL-C) ratio and leptin were significantly reduced in the AOG group after the 12-week walking intervention. However, total cholesterol, HDL-C, and adiponectin/leptin ratio were significantly increased in the AOG group. There was little or no change in these variables in the NWCG group after the 12-week walking intervention.

Conclusions

Our study demonstrated that a 12-week walking intervention may help improve cardiorespiratory fitness and obesity-associated cardiometabolic risk by decrease resting heart rate, modulating blood lipid profiles, and inducing adipokine alterations in obese individuals. Therefore, our research encourages obese young adults to improve their physical health by participating in a 12-week walking program of 10,000 steps a day.

Role of physical activity and cardiorespiratory fitness in metabolically healthy obesity: a narrative review

Obesity has been associated with a multitude of metabolic disorders, often clustering with risk factors of cardiovascular disease and type 2 diabetes mellitus, hypertension, dyslipidaemia. Overall, obesity is a worldwide, growing health concern. However, a subgroup of obese individuals with a low burden of metabolic abnormalities have been identified and described as metabolically healthy obese (MHO). Whether the MHO phenotype is protective against obesity-related metabolic disorders in the long-term is presently unclear, and current research examining the potential transition has yielded inconsistent results. In this current narrative review, we aim to provide insights on the role of physical activity (PA) and cardiorespiratory fitness (CRF) in MHO. Lifestyle factors such as PA and CRF may influence the MHO phenotype. Limited studies have characterised energy expenditure and CRF in MHO and metabolically unhealthy obese. However, higher levels of PA, less sedentary behaviour and higher CRF have been observed in MHO individuals. Considering the multiple benefits of PA, it is high time to advocate this lifestyle change beyond its influence on energy balance in a weight loss programme to improve cardiovascular and metabolic risk factors irrespective of body weight and fat mass changes. Improved CRF via increased PA, especially exercise participation, while avoiding weight gain is not only a realistic goal, but should be the primary intervention for MHO populations to prevent the transition to an abnormal metabolic state.

Effects of fitness and fatness on age-related arterial stiffening in people with type 2 diabetes

People with type 2 diabetes (T2D) are at a greater risk of cardiovascular disease than the general population. Both non-modifiable (age) and modifiable (low aerobic fitness, high body fatness) factors are separately predictive of cardiovascular risk, although they often occur concomitantly. This study aimed to examine the (1) association between age and arterial stiffness, a subclinical marker of cardiovascular risk; and (2) effects of body fatness and aerobic fitness on age-related increases in arterial stiffness in people with T2D. Data from 64 individuals with T2D (age 59.8 ± 8.7 years, 40% female, HbA_1c 8.4 ± 1.6%) were included in this cross-sectional analysis. Carotid-femoral pulse wave velocity (cfPWV) was used to quantify arterial stiffness. Aerobic fitness (relative V̇O_2peak ) was determined via indirect calorimetry during maximal exercise testing. Central body fatness was determined using waist circumference. Data were analysed using hierarchical multiple regressions. After adjustment for sex and duration of T2D, each one standard deviation (SD) increase in age (8.68 years) was associated with a 0.63 m·s^-1 increase in cfPWV (β = 0.416, p = 0.001). Following adjustment for aerobic fitness and body fatness, the standardized β was unchanged (0.417). A one SD increase in waist circumference (13.9 cm) and relative V̇O_2peak (5.3 ml·kg^-1 ·min^-1 ) were associated with a similar magnitude of difference in cfPWV (0.47 m·s^-1 and -0.44 m·s^-1 , respectively). Therefore, age is a significant correlate of increased arterial stiffness in T2D, with higher aerobic fitness attenuating, and higher body fatness exacerbating, this increase. Interventions aimed at improving cardiovascular outcomes in people with T2D should target both increased aerobic fitness and reduced body fatness.

Joint Associations of Obesity and Cardiorespiratory Fitness With Coronary Artery Calcium Composition: IS THERE EVIDENCE FOR FAT-BUT-FIT?

INTRODUCTION

The purpose of this study was to examine the individual and joint associations of obesity and cardiorespiratory fitness (CRF) with indices of coronary artery calcification (CAC) in 2090 middle-aged men.

METHODS

Obesity was defined as a body mass index (BMI) ≥25 kg/m2 and a waist circumference (WC) ≥90 cm. Cardiorespiratory fitness was operationally defined as peak oxygen uptake (V˙o2peak) directly measured using gas analysis. Participants were then divided into unfit and fit categories based on age-specific V˙o2peak percentiles. Agatston scores >100 and volume and density scores >75th percentile were defined as indices of CAC, signifying advanced subclinical atherosclerosis.

RESULTS

Obese men had increased CAC Agatston, volume, and density scores, while higher CRF was associated with lower Agatston and volume scores after adjusting for potential confounders. In the joint analysis, unfit-obese men had higher CAC Agatston and CAC volume. The fit-obesity category was not associated with CAC Agatston (OR = 0.91: 95% CI, 0.66-1.25, for BMI and OR = 1.21: 95% CI, 0.86-1.70, for WC) and CAC volume (OR = 1.14: 95% CI, 0.85-1.53, for BMI and OR = 1.23: 95% CI, 0.90-1.69, for WC), which were similar to estimates for the fit-normal weight category.

CONCLUSIONS

These findings demonstrate that while obesity is positively associated with the prevalence of moderate to severe CAC scores, CRF is inversely associated with the prevalence of moderate to severe CAC scores. Additionally, the combination of being fit and obese was not associated with CAC scores, which could potentially reinforce the fat-but-fit paradigm.

Group Lifestyle Intervention With Mobile Health for Young Adults With Serious Mental Illness: A Randomized Controlled Trial

OBJECTIVE

Evidence-based lifestyle interventions tailored to young adults with serious mental illness are needed to reduce their cardiometabolic risk. This study evaluated the effectiveness of a group lifestyle intervention ("PeerFIT") enhanced with mobile health (mHealth) compared with one-on-one mHealth coaching (basic education supported by activity tracking [BEAT]) for young adults with serious mental illness who were overweight or obese.

METHODS

Participants were young adults ages 18-35 years with serious mental illness and a body mass index ≥25 kg/m², who were randomly assigned to PeerFIT or BEAT. Research staff collected data at baseline and at 6 and 12 months. Main outcomes were clinically significant changes from baseline in weight (≥5% weight loss), cardiorespiratory fitness (CRF; increase of >50 m on the 6-minute walk test), and cardiovascular disease (CVD) risk reduction (clinically significant weight loss or CRF improvement).

RESULTS

Participants were 150 young adults with a mean ± SD body mass index of 37.1±7.4. Intent-to-treat analyses revealed no significant between-group difference for weight-loss, CRF, or CVD outcomes at 6 and 12 months. Participants in both conditions achieved clinically significant CVD risk reduction, weight loss, and CRF from baseline to 6 and 12 months, and all these improvements were statistically significant (p<0.01).

CONCLUSION

The PeerFIT group lifestyle intervention was not superior to one-on-one mHealth coaching in achieving clinically significant changes in weight, CRF, and CVD risk reduction. Although both interventions improved outcomes, low-intensity mHealth coaching may be a more scalable approach for addressing modifiable cardiometabolic risk factors among young adults with serious mental illness.

The genetic case for cardiorespiratory fitness as a clinical vital sign and the routine prescription of physical activity in healthcare

BACKGROUND

Cardiorespiratory fitness (CRF) and physical activity (PA) are well-established predictors of morbidity and all-cause mortality. However, CRF is not routinely measured and PA not routinely prescribed as part of standard healthcare. The American Heart Association (AHA) recently presented a scientific case for the inclusion of CRF as a clinical vital sign based on epidemiological and clinical observation. Here, we leverage genetic data in the UK Biobank (UKB) to strengthen the case for CRF as a vital sign and make a case for the prescription of PA.

METHODS

We derived two CRF measures from the heart rate data collected during a submaximal cycle ramp test: CRF-vo2max, an estimate of the participants' maximum volume of oxygen uptake, per kilogram of body weight, per minute; and CRF-slope, an estimate of the rate of increase of heart rate during exercise. Average PA over a 7-day period was derived from a wrist-worn activity tracker. After quality control, 70,783 participants had data on the two derived CRF measures, and 89,683 had PA data. We performed genome-wide association study (GWAS) analyses by sex, and post-GWAS techniques to understand genetic architecture of the traits and prioritise functional genes for follow-up.

RESULTS

We found strong evidence that genetic variants associated with CRF and PA influenced genetic expression in a relatively small set of genes in the heart, artery, lung, skeletal muscle and adipose tissue. These functionally relevant genes were enriched among genes known to be associated with coronary artery disease (CAD), type 2 diabetes (T2D) and Alzheimer's disease (three of the top 10 causes of death in high-income countries) as well as Parkinson's disease, pulmonary fibrosis, and blood pressure, heart rate, and respiratory phenotypes. Genetic variation associated with lower CRF and PA was also correlated with several disease risk factors (including greater body mass index, body fat and multiple obesity phenotypes); a typical T2D profile (including higher insulin resistance, higher fasting glucose, impaired beta-cell function, hyperglycaemia, hypertriglyceridemia); increased risk for CAD and T2D; and a shorter lifespan.

CONCLUSIONS

Genetics supports three decades of evidence for the inclusion of CRF as a clinical vital sign. Given the genetic, clinical and epidemiological evidence linking CRF and PA to increased morbidity and mortality, regular measurement of CRF as a marker of health and routine prescription of PA could be a prudent strategy to support public health.

Chronic venous disease and diabetic microangiopathy: pathophysiology and commonalities

Chronic venous disease and diabetes mellitus are highly prevalent and debilitating conditions affecting millions of individuals globally. Although these conditions are typically considered as separate entities, they often co-exist which may be important in both understanding their pathophysiology and determining the best treatment strategy. Diabetes mellitus is twice as common in patients with chronic venous disease compared with the general population. Notably, a large proportion of patients with diabetes mellitus present with venous disorders, although this is often overlooked. The etiology of chronic venous disease is multifactorial, involving hemodynamic, genetic, and environmental factors which result in changes to the venous endothelium and structural wall as well as inflammation. Inflammation, endothelial dysfunction and hyperfiltration or leakage, are commonly observed in diabetes mellitus and cause various diabetic microvascular complications. Both diseases are also influenced by the increased expression of adhesion molecules, chemokines, and cytokines, and are characterized by the presence of vessel hypertension. Consequently, despite differences in etiology, the pathophysiology of both chronic venous disease and diabetic microangiopathy appears to be driven by endothelial dysfunction and inflammation. Treatment strategies should take the co-existence of chronic venous disease and diabetic microangiopathy into account. Compression therapy is recommended in inflammatory conditions that have an edema component as seen in both chronic venous disease and diabetes mellitus. Lifestyle changes like weight loss and exercise, will improve metabolic state and lower inflammation and should be promoted in these patients. Additionally, both patient populations may benefit from venoactive drugs.

Vascular improvements in individuals with type 2 diabetes following a 1 year randomised controlled exercise intervention, irrespective of changes in cardiorespiratory fitness

AIMS/HYPOTHESIS

Vascular changes in individuals with type 2 diabetes mellitus majorly contribute to the development of cardiovascular disease. Increased cardiorespiratory fitness (CRF) has been associated with improvements in vascular health. Although CRF tends to improve with exercise training, there remains a portion of participants with little or no improvement. Given the importance of vascular function in individuals with type 2 diabetes, we assessed whether individuals who failed to improve CRF following a 1 year exercise intervention also failed to improve arterial stiffness and structural indices.

METHODS

Individuals with type 2 diabetes with no major micro- and macrovascular complications and aged between 30 and 75 years old (n = 63) participated in a three-arm, 1 year, randomised controlled exercise intervention in Lisbon, Portugal. The study involved a non-exercise control group, a moderate continuous training combined with resistance training (RT) group and a high-intensity interval training with RT group. Allocation of participants into the intervention and control groups was done using a computer-generated list of random numbers. An improvement in CRF was defined as a change in [Formula: see text] ≥5%. Vascular stiffness and structural indices were measured using ultrasound imaging and applanation tonometry. Generalised estimating equations were used to compare changes in vascular measures across individuals in the control group (n = 22) and those in the exercise groups who either had improved CRF (CRF responders; n = 14) or whose CRF did not improve (CRF non-responders; n = 27) following 1 year of exercise training.

RESULTS

Compared with the control group, exercisers, with and without improvements in CRF, had decreased carotid intima-media thickness (IMT) (CRF responders: β = -2.84 [95% CI -5.63, -0.04]; CRF non-responders: β = -5.89 [95% CI -9.38, -2.40]) and lower-limb pulse wave velocity (PWV) (CRF responders: β = -0.14 [95% CI -0.25, -0.03]; CRF non-responders: β = -0.14 [95% CI -0.25, -0.03]), the latter being an indicator of peripheral arterial stiffness. Only CRF responders had decreased PWV of the upper limb compared with control participants (β = -0.12 [95% CI -0.23, -0.01]). As for central stiffness, CRF non-responders had increased aortic PWV compared with CRF responders (β = 0.19 [95% CI 0.07, 0.31]), whereas only the CRF non-responders had altered carotid distensibility coefficient compared with the control group (β = 0.00 [95% CI 3.01 × 10^-5, 0.00]). No interaction effects between the CRF responders and non-responders vs control group were found for the remaining stiffness or haemodynamic indices (p>0.05).

CONCLUSIONS/INTERPRETATION

Regardless of improvements in CRF, individuals with type 2 diabetes had significant improvements in carotid IMT and lower-limb arterial stiffness following a 1 year exercise intervention. Thus, a lack of improvement in CRF following exercise in people with type 2 diabetes does not necessarily entail a lack of improvement in vascular health.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03144505 FUNDING: This work was supported by fellowships from the Portuguese Foundation for Science and Technology. This work is also financed by a national grant through the Fundação para a Ciência e Tecnologia (FCT), within the unit I&D 472.

Effects of Polarized Training on Cardiometabolic Risk Factors in Young Overweight and Obese Women: A Randomized-Controlled Trial

Introduction: Volume and intensity are major variables governing exercise training-mediated beneficial effects in both athletes and patients. Although polarized endurance training optimizes and maximizes physiological gains in highly trained individuals, its cardiometabolic protective-effects have not been established. The purpose of the present single site, randomized-controlled trial was to compare the effects of 12-weeks of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and polarized volume training (POL) programs on cardiometabolic risk factors in young overweight and obese women.

Materials and Methods: A total of 64 overweight/obese young women (age 23.3 ± 3.8 years, body mass index 33.8 ± 3.8 kg/m²) were randomly assigned to four groups: control group (CTRL), polarized volume training group, moderate-intensity endurance training group, and HIIT group. The cardiorespiratory capacity, glycemic and lipid profiles, whole-body substrate utilization, and body composition were assessed before and after the intervention.

Results: After the intervention, VO_2peak and power output at VO_2peak increased in all exercised-groups (time effect: p < 0.0001). Power output at VT1 was increased only in the POL group compared to the CTRL group (p = 0.019). Relative fold changes in fasting plasma glucose concentrations decreased only in POL group (p = 0.002). Training induced a significant increase in relative fat oxidation in all the groups (time effect: p < 0.001). Relative fat oxidation increased only in the POL group compared to the CTRL group (training effect: p = 0.032).

Conclusion: Twelve-weeks of polarized volume training showed overall superior effects on cardiorespiratory fitness, basal glycemic control, and substrate oxidation in comparison to MICT and HIIT training modalities. These data suggest that polarized volume training is an effective non-pharmacological treatment strategy for reducing cardiovascular disease risk factors in young overweight and obese women. The trial is registered at ISRCTN, number ISRCTN34421723.

The Importance of Vigorous-Intensity Leisure-Time Physical Activity in Reducing Cardiovascular Disease Mortality Risk in the Obese

OBJECTIVE

To investigate the role of vigorous-intensity leisure-time physical activity in reducing cardiovascular disease (CVD) mortality risk in the obese.

PARTICIPANTS AND METHODS

Trained interviewers assessed physical activity and body mass index (BMI; calculated as the weight in kilograms divided by the height in meters squared) in 59,005 adult participants (mean ± SD age, 57±12 years; 46.5% male) in 2 household-based surveillance studies: Health Survey for England and Scottish Health Survey. Mortality was ascertained from death certificates. Data were collected from January 1, 1994, through March 31, 2011. Cox proportional hazards models were adjusted for age, sex, smoking habit, total physical activity, long-standing illness, prevalent CVD, and occupation.

RESULTS

There were 2302 CVD deaths during 532,251 person-years of follow-up (mean ± SD, 9±4 years). A total of 15,002 (25%) participants were categorized as obese (BMI ≥30). Leisure-time physical activity was inversely associated and BMI was positively associated with CVD mortality. Compared with those who reported meeting physical activity guidelines including some vigorous-intensity physical activity and who had a normal BMI (18.5-24.9) (reference group), the CVD mortality hazard ratio was not significantly different in the obese who also reported meeting physical activity guidelines including some vigorous-intensity physical activities (1.25; 95% CI, 0.50-3.12). Compared with the reference group, the CVD mortality hazard ratio was more than 2-fold in the obese who reported meeting physical activity guidelines, including only moderate-intensity physical activities (2.52; 95% CI, 1.15-2.53).

CONCLUSION

This large, statistically powerful study suggests that vigorous-intensity leisure-time physical activity is important in reducing CVD mortality risk in the obese.

Handgrip strength is associated with insulin resistance and glucose metabolism in adolescents: Evidence from National Health and Nutrition Examination Survey 2011 to 2014

BACKGROUND

Previous studies have reported that handgrip strength, a measure of muscular fitness, is associated with insulin resistance in children and adolescents, with conflicting results. Further, no studies have examined the association between handgrip strength with 2-hour glucose levels.

OBJECTIVE

We tested the association of handgrip strength with measures of insulin resistance (fasting insulin and homeostasis model assessment of insulin resistance [HOMA-IR]) and glucose metabolism (fasting and 2-hour glucose levels) in adolescents from the National Health and Nutrition Examination Survey (NHANES) 2011 to 2014.

METHODS

The study included 959 participants aged 12 to 19 years who underwent a handgrip test and a glucose tolerance test. General linear models were used to examine the associations between handgrip strength and the outcome variables.

RESULTS

After adjustment for age, race, sex, body mass index, and physical activities, handgrip strength was inversely associated with fasting insulin levels (P = .017) and HOMA-IR (P = .025). Although there was no association between handgrip strength and fasting glucose levels (P = .77), handgrip strength was inversely associated with 2-hour glucose levels (P < .0001). Insulin and 2-hour glucose levels decreased linearly as handgrip strength increased from the bottom quartile to the top quartile (P for trend: .045 for fasting insulin levels and .004 for 2-hour glucose levels).

CONCLUSIONS

Muscular fitness, measured by handgrip strength, is associated with insulin resistance and glucose metabolism in adolescents, which indicates that increasing muscular fitness may have beneficial effects for early prevention of insulin resistance and type 2 diabetes.

The association between leisure-time physical activity, low HDL-cholesterol and mortality in a pooled analysis of nine population-based cohorts

The objective of this study was to investigate associations between leisure-time physical activity, low high-density lipoprotein cholesterol (HDL-C) and mortality. Self-reported leisure-time physical activity, HDL-C concentration, and mortality were assessed in 37,059 adults in Health Survey for England and Scottish Health Survey. Meeting physical activity guidelines was defined as ≥150 min wk⁻¹ of moderate-intensity activity, ≥75 min wk⁻¹ of vigorous-intensity activity, or equivalent combinations. Low HDL-C was defined as <1.03 mmol L⁻¹. Cox proportional hazard models were adjusted for age, sex, smoking, total cholesterol, systolic blood pressure, body mass index, longstanding illness, and socioeconomic status. There were 2250 deaths during 326,016 person-years of follow-up. Compared with those who met physical activity guidelines and whose HDL-C was normal (reference group), all-cause mortality risk was not elevated in those who met physical activity guidelines and whose HDL-C concentration was low (hazard ratio: 1.07; 95% confidence interval: 0.75, 1.53). Compared with the reference group, all-cause mortality risk was elevated in those who did not meet physical activity guidelines and whose HDL-C was normal (1.37; 1.16, 1.61), and in those who did not meet physical activity guidelines and whose HDL-C was low (1.65; 1.37, 1.98). Cardiovascular disease mortality hazard ratios were similar, although confidence intervals were wider. There was no statistically significant evidence of biological interaction between physical inactivity and low HDL-C. This novel study supports the notion that leisure-time physical activity be recommended in those with low HDL-C concentration who may be resistant to the HDL-raising effect of exercise training.

Relation of Cardiorespiratory Fitness to Risk of Subclinical Atherosclerosis in Men With Cardiometabolic Syndrome

We tested the hypothesis that cardiometabolic syndrome (CMS) is associated with subclinical atherosclerosis in men and that moderate-to-high levels of cardiorespiratory fitness (fitness) attenuate this relation. Our study population (n = 2,107 men) participated in a health screening program that included measures of coronary artery calcification (CAC) and carotid artery intima-media thickness (CIMT) as surrogate markers of subclinical atherosclerosis. The prevalence of subclinical atherosclerosis was defined as a CAC score >0 and a mean CIMT more than the seventy-fifth percentile. Fitness was directly measured through peak oxygen consumption during cardiopulmonary exercise testing to volitional fatigue/exhaustion. The presence of CMS was defined as having ≥3 relevant risk factors based on the Adult Treatment Panel III report (ATP-III) criteria. After adjusting for confounding variables, participants with CMS demonstrated a higher odds ratio (OR) of having a positive CAC (OR 1.41, 95% confidence interval [CI] 1.05 to 1.89) and CIMT (OR 1.70, 95% CI 1.14 to 2.52) compared with those without CMS. Upper levels of fitness were associated with a lower prevalence of CAC (OR 0.69, 95% CI 0.55 to 0.88) and CIMT (OR 0.53, 95% CI 0.40 to 0.71) compared with lower fitness. In the joint analysis, unfit participants with CMS were 1.47 times (95% CI 1.09 to 1.96 for CAC) and 2.35 times (95% CI 1.70 to 3.26 for CIMT) more likely to exhibit these indexes of subclinical atherosclerosis compared with fit participants without CMS. Fit participants with CMS had ORs for the prevalence of CAC (OR 1.12; 95% CI 0.85 to 1.47) and CIMT (OR 1.06; 95% CI 0.74 to 1.53) that were similar to those of the fit cohort without CMS. In conclusion, our findings demonstrate that CMS is associated with an increased risk of subclinical atherosclerosis but that high fitness appears to attenuate these associations in men.

Effect of intermittent cold exposure on brown fat activation, obesity, and energy homeostasis in mice

Homeotherms have specific mechanisms to maintain a constant core body temperature despite changes in thermal environment, food supply, and metabolic demand. Brown adipose tissue, the principal thermogenic organ, quickly and efficiently increases heat production by dissipating the mitochondrial proton motive force. It has been suggested that activation of brown fat, via either environmental (i.e. cold exposure) or pharmacologic means, could be used to increase metabolic rate and thus reduce body weight. Here we assess the effects of intermittent cold exposure (4°C for one to eight hours three times a week) on C57BL/6J mice fed a high fat diet. Cold exposure increased metabolic rate approximately two-fold during the challenge and activated brown fat. In response, food intake increased to compensate fully for the increased energy expenditure; thus, the mice showed no reduction in body weight or adiposity. Despite the unchanged adiposity, the cold-treated mice showed transient improvements in glucose homeostasis. Administration of the cannabinoid receptor-1 inverse agonist AM251 caused weight loss and improvements in glucose homeostasis, but showed no further improvements when combined with cold exposure. These data suggest that intermittent cold exposure causes transient, meaningful improvements in glucose homeostasis, but without synergy when combined with AM251. Since energy expenditure is significantly increased during cold exposure, a drug that dissociates food intake from metabolic demand during cold exposure may achieve weight loss and further metabolic improvements.

Changes in fitness and fatness on the development of cardiovascular disease risk factors hypertension, metabolic syndrome, and hypercholesterolemia

OBJECTIVES

This study sought examine the independent and combined associations of changes in fitness and fatness with the subsequent incidence of the cardiovascular disease (CVD) risk factors of hypertension, metabolic syndrome, and hypercholesterolemia.

BACKGROUND

The relative and combined contributions of fitness and fatness to health are controversial, and few studies are available on the associations of changes in fitness and fatness with the development of CVD risk factors.

METHODS

We followed up 3,148 healthy adults who received at least 3 medical examinations. Fitness was determined by using a maximal treadmill test. Fatness was expressed by percent body fat and body mass index. Changes in fitness and fatness between the first and second examinations were categorized into loss, stable, or gain groups.

RESULTS

During the 6-year follow-up after the second examination, 752, 426, and 597 adults developed hypertension, metabolic syndrome, and hypercholesterolemia, respectively. Maintaining or improving fitness was associated with lower risk of developing each outcome, whereas increasing fatness was associated with higher risk of developing each outcome, after adjusting for possible confounders and fatness or fitness for each other (all p for trend <0.05). In the joint analyses, the increased risks associated with fat gain appeared to be attenuated, although not completely eliminated, when fitness was maintained or improved. In addition, the increased risks associated with fitness loss were also somewhat attenuated when fatness was reduced.

CONCLUSIONS

Both maintaining or improving fitness and preventing fat gain are important to reduce the risk of developing CVD risk factors in healthy adults.

Proximal correlates of metabolic phenotypes during 'at-risk' and 'case' stages of the metabolic disease continuum

OBJECTIVE

To examine the social and behavioural correlates of metabolic phenotypes during 'at-risk' and 'case' stages of the metabolic disease continuum.

DESIGN

Cross-sectional study of a random population sample.

PARTICIPANTS

A total of 718 community-dwelling adults (57% female), aged 18-92 years from a regional South Australian city.

MEASUREMENTS

Total body fat and lean mass and abdominal fat mass were assessed by dual energy x-ray absorptiometry. Fasting venous blood was collected in the morning for assessment of glycated haemoglobin, plasma glucose, serum triglycerides, cholesterol lipoproteins and insulin. Seated blood pressure (BP) was measured. Physical activity and smoking, alcohol and diet (96-item food frequency), sleep duration and frequency of sleep disordered breathing (SDB) symptoms, and family history of cardiometabolic disease, education, lifetime occupation and household income were assessed by questionnaire. Current medications were determined by clinical inventory.

RESULTS

36.5% were pharmacologically managed for a metabolic risk factor or had known diabetes ('cases'), otherwise were classified as the 'at-risk' population. In both 'at-risk' and 'cases', four major metabolic phenotypes were identified using principal components analysis that explained over 77% of the metabolic variance between people: fat mass/insulinemia (FMI); BP; lipidaemia/lean mass (LLM) and glycaemia (GLY). The BP phenotype was uncorrelated with other phenotypes in 'cases', whereas all phenotypes were inter-correlated in the 'at-risk'. Over and above other socioeconomic and behavioural factors, medications were the dominant correlates of all phenotypes in 'cases' and SDB symptom frequency was most strongly associated with FMI, LLM and GLY phenotypes in the 'at-risk'.

CONCLUSION

Previous research has shown FMI, LLM and GLY phenotypes to be most strongly predictive of diabetes development. Reducing SDB symptom frequency and optimising the duration of sleep may be important concomitant interventions to standard diabetes risk reduction interventions. Prospective studies are required to examine this hypothesis.

Physical activity, stress reduction, and mood: insight into immunological mechanisms

Psychosocial factors, such as chronic mental stress and mood, are recognized as an important predictor of longevity and wellbeing. In particular, depression is independently associated with cardiovascular disease and all-cause mortality, and is often comorbid with chronic diseases that can worsen their associated health outcomes. Regular exercise is thought to be associated with stress reduction and better mood, which may partly mediate associations between depression, stress, and health outcomes. The underlying mechanisms for the positive effects of exercise on wellbeing remain poorly understood. In this overview we examine epidemiological evidence for an association between physical activity and mental health. We then describe the exercise withdrawal paradigm as an experimental protocol to study mechanisms linking exercise, mood, and stress. In particular we will discuss the potential role of the inflammatory response as a central mechanism.

Association between cardiorespiratory fitness and arterial stiffness in men with the metabolic syndrome

AIMS

We tested the hypothesis that high cardiorespiratory fitness (fitness) is associated with lower levels of arterial stiffness in 1035 (age 52 ± 6 years) men with and without the metabolic syndrome.

METHODS

Arterial stiffness was derived from brachial-ankle pulse wave velocity (baPWV). Fitness was directly measured by peak oxygen uptake during a standard treadmill test.

RESULTS

Men with the metabolic syndrome (n = 168) had significantly higher baPWV than men without the metabolic syndrome (1424 ± 175 cm/s vs. 1333 ± 150 cm/s, p < 0.05). When separated according to quartiles of fitness, men with and without the metabolic syndrome in the highest quartile of fitness had significantly lower baPWV compared to men in the lowest quartile of fitness (p < 0.05). Fitness was inversely correlated with baPWV in men with (p = -0.29, p < 0.05) and without the metabolic syndrome (p = -0.22, p < 0.05). There was no differences in baPWV levels between fit men with the metabolic syndrome and unfit men without the metabolic syndrome (fit/MetS; 1366 ± 140 vs. unfit/no MetS; 1401 ± 194 cm/s, p = 0.81).

CONCLUSIONS

These results demonstrate that high fitness is inversely associated with arterial stiffness in men with and without the metabolic syndrome. Increased arterial stiffness in the metabolic syndrome is attenuated by high fitness.

The ABC of Physical Activity for Health: a consensus statement from the British Association of Sport and Exercise Sciences

Our understanding of the relationship between physical activity and health is constantly evolving. Therefore, the British Association of Sport and Exercise Sciences convened a panel of experts to review the literature and produce guidelines that health professionals might use. In the ABC of Physical Activity for Health, A is for All healthy adults, B is for Beginners, and C is for Conditioned individuals. All healthy adults aged 18-65 years should aim to take part in at least 150 min of moderate-intensity aerobic activity each week, or at least 75 min of vigorous-intensity aerobic activity per week, or equivalent combinations of moderate- and vigorous-intensity activities. Moderate-intensity activities are those in which heart rate and breathing are raised, but it is possible to speak comfortably. Vigorous-intensity activities are those in which heart rate is higher, breathing is heavier, and conversation is harder. Aerobic activities should be undertaken in bouts of at least 10 min and, ideally, should be performed on five or more days a week. All healthy adults should also perform muscle-strengthening activities on two or more days a week. Weight training, circuit classes, yoga, and other muscle-strengthening activities offer additional health benefits and may help older adults to maintain physical independence. Beginners should work steadily towards meeting the physical activity levels recommended for all healthy adults. Even small increases in activity will bring some health benefits in the early stages and it is important to set achievable goals that provide success, build confidence, and increase motivation. For example, a beginner might be asked to walk an extra 10 min every other day for several weeks to slowly reach the recommended levels of activity for all healthy adults. It is also critical that beginners find activities they enjoy and gain support in becoming more active from family and friends. Conditioned individuals who have met the physical activity levels recommended for all healthy adults for at least 6 months may obtain additional health benefits by engaging in 300 min or more of moderate-intensity aerobic activity per week, or 150 min or more of vigorous-intensity aerobic activity each week, or equivalent combinations of moderate- and vigorous-intensity aerobic activities. Adults who find it difficult to maintain a normal weight and adults with increased risk of cardiovascular disease or type 2 diabetes may in particular benefit from going beyond the levels of activity recommended for all healthy adults and gradually progressing towards meeting the recommendations for conditioned individuals. Physical activity is beneficial to health with or without weight loss, but adults who find it difficult to maintain a normal weight should probably be encouraged to reduce energy intake and minimize time spent in sedentary behaviours to prevent further weight gain. Children and young people aged 5-16 years should accumulate at least 60 min of moderate-to-vigorous-intensity aerobic activity per day, including vigorous-intensity aerobic activities that improve bone density and muscle strength.