Fatness, fitness, and cardiometabolic risk factors in middle-aged white men

Uncertain association between maximal fat oxidation during exercise and cardiometabolic risk factors in healthy sedentary adults

The present work examines the relationships between maximal fat oxidation during a graded exercise test (MFO), the intensity of exercise that elicits MFO (Fat_max), and traditional cardiometabolic risk factors in healthy, sedentary adults. A total of 119 (81 women) young, sedentary adults (22.1 ± 2.2 years old), and 71 (37 women) middle-aged, sedentary adults (53.4 ± 4.9 years old) participated in the current study. Systolic and diastolic blood pressures were determined following standard procedures. Plasma glucose, insulin, total cholesterol, high-density lipoprotein cholesterol and triglycerides were determined in a fasted state and the homeostatic model assessment of insulin resistance index and low-density lipoprotein cholesterol levels subsequently calculated. A sex and age group-specific cardiometabolic risk Z-score was also calculated for each subject based on waist circumference, systolic and diastolic blood pressure, plasma glucose, high-density lipoprotein cholesterol and triglycerides. MFO and Fat_max were determined using a walking graded exercise test using indirect calorimetry. No clear association was seen of MFO and Fat_max with any cardiometabolic risk factor (all P≥0.05), except for a weak, inverse association between Fat_max and the fatty liver index (P=0.027). Similarly, neither MFO nor Fat_max was apparently associated with the cardiometabolic risk Z-score (all P≥0.05). The current findings suggest an uncertain association of MFO and Fat_max during a graded exercise test with the cardiometabolic profile of healthy, sedentary adults.HighlightsThe study of the physiological mechanisms that trigger the onset of metabolic disorders has received considerable attention in recent years, with changes in MFO and Fat_max being highlighted as a potential key factor.This work shows that MFO and Fat_max during a graded exercise test are not associated with the cardiometabolic profile in sedentary, healthy adults.Further studies are needed to elucidate which other physiological disorders are related to cardiometabolic risk.

The association between recreational screen time and cancer risk: findings from the UK Biobank, a large prospective cohort study

Background

Evidence is suggestive of sedentary behaviour being associated with an increased risk of endometrial cancer, but the evidence base is too limited to draw any conclusions for other cancers. The aim of the study was to investigate the association between recreational screen time and site-specific cancer risk.

Methods

We analysed data from the prospective UK Biobank cohort study. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between daily recreational screen time (including television (TV) viewing time, computer use time and total screen time) and site-specific cancer risk. Partition models and isotemporal substitution models investigated the impact of substituting recreational screen time with physical activity.

Results

During a mean follow-up of 7.6 years, 28,992 incident cancers were identified among 470,578 adults. A 1-h increase in daily TV viewing time was associated with higher risks of oropharyngeal, oesophago-gastric and colon cancer in fully adjusted models. Participants who reported ≤1, compared with 1- ≤ 3, hours/day of TV viewing time had lower risks of lung, breast, and oesophago-gastric cancer. Findings were inconsistent for daily recreational computer use and daily total recreational screen time. The majority of observed associations were small, and were attenuated after excluding cancers diagnosed within the first two years of follow-up, except for oesophago-gastric and colon cancers (HR 1.05, 95% CI: 1.01, 1.10; and HR 1.04, 95% CI: 1.01, 1.07 per 1-h increase in daily TV viewing time, respectively). However, isotemporal substitution models showed reduced risk of some site-specific (oropharyngeal, lung, breast and colorectal) cancers when replacing 1-h/day of TV viewing with 1-h of moderate-intensity physical activity or walking.

Conclusions

Our findings show that daily recreational screen time, particularly TV viewing, was associated with small increased risks of oesophago-gastric and colon cancer. Replacing 1-h/day of TV viewing with 1-h of moderate-intensity physical activity or walking was associated with lower risk of oropharyngeal, lung, breast and colorectal cancers. Further research from other large prospective cohort studies is required, while mechanistic research is warranted to enhance the biological plausibility of these findings.

Cardiorespiratory Fitness Does Not Offset Adiposity-Related Systemic Inflammation in Physically Active Older Women

CONTEXT

Chronic inflammation increases diabetes risk and may be exacerbated by excess adipose tissue. Whether cardiovascular fitness can offset chronic inflammation associated with excess adipose tissue in older adults is unclear.

OBJECTIVE

The study aimed to examine the influence of cardiorespiratory fitness on links between adiposity and pro- and anti-inflammatory biomarkers related to metabolic risk in physically active older women.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional study comprising older community-dwelling women (n = 109; age, 65-70 yr).

MAIN OUTCOME

Cardiorespiratory fitness was assessed using a standardized submaximal test and participants were categorized into high and low adiposity-related metabolic risk (body mass index, waist-to-hip ratio (WHR) and total fat mass). The inflammatory biomarkers C-reactive protein (CRP), interleukin-6 (IL-6), IL-10, IL-18, adiponectin, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein (MIP-1α) were analyzed.

RESULTS

Regardless of adiposity measure, women in the metabolic high-risk group had significantly (P<0.05) elevated CRP and lower adiponectin levels. Levels of IL-6 and MIP1-α were significantly elevated in the high-risk group defined by WHR and total fat mass. IL-18 level was significantly elevated in the high-risk group based on WHR only. Importantly, a high cardiorespiratory fitness level did not attenuate the detrimental links between adiposity measures and inflammation.

CONCLUSIONS

Altogether, cardiorespiratory fitness does not offset the detrimental links between adiposity and several inflammatory biomarkers related to metabolic risk in physically active older women. Reducing abdominal adipose tissue in older adults should be emphasized in efforts aiming to attenuate age-related systemic inflammation and metabolic risk regardless of cardiorespiratory fitness.

Association Between Visceral Fat Accumulation and Exercise Tolerance in Non-Obese Subjects Without Diabetes

Background

We examined the associations between visceral fat accumulation, presence of the components of metabolic syndrome (MetS), and exercise tolerance in non-obese subjects without diabetes.

Methods

Seventy-four non-obese, non-diabetic Japanese men were enrolled. The subjects were divided into the following two groups: non-obese subjects without any MetS risk factors (n = 38, Group A) and non-obese subjects with one or two MetS risk factors (n = 36, Group B). Anthropometric and metabolic parameters were measured. The response of heart rate (HR) and blood pressure (BP), and exercise tolerance were also evaluated with a cardiopulmonary exercise test using a bicycle ergometer.

Results

The body mass index, abdominal circumference, visceral fat area, and homeostasis model assessment-insulin resistance, were significantly higher, while levels of anaerobic threshold and maximal oxygen uptake were significantly lower in Group B than in Group A. The levels of resting HR, resting BP, and BP at maximal exercise were significantly higher in Group B than in Group A. There were no significant differences in the HR at maximal exercise as well as the HR and BP after exercise between the two groups. The visceral fat area was significantly and negatively correlated with exercise tolerance. Multivariate linear regression analyses demonstrated that visceral fat area, but not abdominal circumference, was significantly and independently associated with maximal oxygen uptake.

Conclusions

These data suggest that the visceral fat area is a significant determinant for exercise tolerance even in non-obese subjects without diabetes.

Sex-specific differences in hypertension and associated cardiovascular disease

Although intrinsic mechanisms that regulate arterial blood pressure (BP) are similar in men and women, marked variations exist at the molecular, cellular and tissue levels. These physiological disparities between the sexes likely contribute to differences in disease onset, susceptibility, prevalence and treatment responses. Key systems that are important in the development of hypertension and cardiovascular disease (CVD), including the sympathetic nervous system, the renin-angiotensin-aldosterone system and the immune system, are differentially activated in males and females. Biological age also contributes to sexual dimorphism, as premenopausal women experience a higher degree of cardioprotection than men of similar age. Furthermore, sex hormones such as oestrogen and testosterone as well as sex chromosome complement likely contribute to sex differences in BP and CVD. At the cellular level, differences in cell senescence pathways may contribute to increased longevity in women and may also limit organ damage caused by hypertension. In addition, many lifestyle and environmental factors - such as smoking, alcohol consumption and diet - may influence BP and CVD in a sex-specific manner. Evidence suggests that cardioprotection in women is lost under conditions of obesity and type 2 diabetes mellitus. Treatment strategies for hypertension and CVD that are tailored according to sex could lead to improved outcomes for affected patients.

What is the most effective exercise protocol to improve cardiovascular fitness in overweight and obese subjects?

BACKGROUND

Increased peak oxygen consumption (VO_2peak) can reduce cardiovascular risks associated with obesity. Our aim was to analyze the effect of a weight loss program on cardiovascular fitness in overweight (W) and obese (O) subjects.

METHODS

One hundred and sixty-seven subjects (77 males and 90 females), aged 18-50 years, performed a modified Bruce protocol before (pre) and after (post) a weight loss program of 24 weeks. This program combined physical training (strength, S; endurance, E; combined strength + endurance, SE; or physical activity recommendation, PA) 3 times per week, with a 25%-30% caloric restriction diet.

RESULTS

VO_2peak improved in overweight and obese males (pre and post values in L/min, respectively; W = 3.2 ± 0.6 vs. 3.7 ± 0.5, p < 0.001; O = 3.6 ± 0.6 vs. 3.8 ± 0.6, p = 0.013) as well as in overweight females (2.0 ± 0.3 vs. 2.3 ± 0.4, p < 0.001). VO_2peak in the first ventilatory threshold (VT₁) increased for all 4 interventions in males (p < 0.05), except for S in the obese group (1.6 ± 0.2 vs. 1.7 ± 0.3, p = 0.141). In females, it increased in E (0.9 ± 0.2 vs. 1.4 ± 0.3, p < 0.001), SE (0.9 ± 0.2 vs. 1.2 ± 0.4, p = 0.003), and PA (0.9 ± 0.1 vs. 1.2 ± 0.2, p = 0.006) in overweight groups. Time-to-exhaustion improved in all subjects except for females in PA group (15.7 ± 0.3 min vs. 15.9 ± 0.3 min, p = 0.495).

CONCLUSION

Our results suggest that all methods, including the recommendation of physical activity, can improve cardiovascular fitness in overweight subjects and obese males.

Sedentary behavior and compensatory mechanisms in response to different doses of exercise-a randomized controlled trial in overweight and obese adults

BACKGROUND/OBJECTIVES

To examine compensatory changes in sedentary behavior (SB) and light-intensity physical activities (LIPA) in response to a 22-week exercise training program in overweight/obese adults; and to determine if different forms of exercise training and physical activity recommendations interact with these compensatory changes.

SUBJECTS/METHODS

Eighty-nine overweight and obese individuals (body mass index (BMI): 25-34.9 kg/m², 48% males), aged 18-50 years, were randomized into four intervention groups (strength, endurance, combined strength + endurance and physical activity recommendations) with a 25-30% caloric restriction of total daily energy expenditure for 22 weeks. Energy expenditure was measured by accelerometry before, during and after the program.

RESULTS

LIPA increased significantly (P<0.001) after three months and at the end of intervention compared to baseline (pre: 281±9 min; 3 months: 303±9 min; post: 312±8 min). SB percentage decreased by 5.3 at the end of the intervention (P=0.002). No interactions were observed between groups or sexes. Significant correlations were found between SB and body weight, fat mass, android fat mass and lean body mass before and after the intervention (P<0.05). LIPA was also significantly correlated with all these body composition variables in the pre-intervention, but only correlated with body weight at the end of intervention.

CONCLUSIONS

There were no compensatory changes after a combined exercise and diet program; where minutes in LIPA increased and %SB decreased after the program, without differences among exercise modes. Greater physical activity levels can contribute to a better percentage and distribution of body tissues.

Cardiorespiratory fitness testing and cardiovascular disease risk in male steelworkers

BACKGROUND

The workplace has been advocated as a setting to perform cardiovascular disease (CVD) risk assessments. These risk assessments usually focus on traditional risk factors rather than cardiorespiratory fitness (CRF) despite established associations between CRF and CVD. The lack of guidance on interpreting health-related CRF values has been suggested as a barrier to utilizing CRF in practice.

AIMS

To assess the merits of CRF testing in the workplace and explore whether a CRF value identified male individuals above the recommended threshold for further clinical investigation.

METHODS

Cross-sectional analysis of male steelworkers from Carmarthenshire, South Wales, UK who completed a workplace-based CVD risk assessment with an added CRF protocol based on heart rate responses (Chester Step Test). Receiver operating characteristic (ROC) analysis was undertaken to explore the possibility of a CRF value to identify individuals at an increased 10-year risk of CVD (QRISK2 ≥ 10%).

RESULTS

There were 81 participants. ROC analysis revealed that a CRF level of 34.5ml/kg/min identified those individuals above the ≥10% QRISK2 threshold with the best sensitivity (0.800) and specificity (0.687) to discriminate against true- and false-positive rates. Further analysis revealed that individuals with either 'Average' or 'Below Average' CRF would be five times more likely to have a 10-year CVD risk above the ≥10% QRISK2 threshold than individuals with an 'Excellent' or 'Good' level of fitness [OR 5.10 (95% CI 1.60-16.3)].

CONCLUSIONS

This study suggests CRF assessments are a useful addition to a workplace CVD assessment and could identify male individuals at increased predicted risk of the condition.

Association of Fitness With Incident Dyslipidemias Over 25 Years in the Coronary Artery Risk Development in Young Adults Study

INTRODUCTION

Few studies have examined the longitudinal associations of fitness or changes in fitness on the risk of developing dyslipidemias. This study examined the associations of (1) baseline fitness with 25-year dyslipidemia incidence and (2) 20-year fitness change on dyslipidemia development in middle age in the Coronary Artery Risk Development in Young Adults Study (CARDIA).

METHODS

Multivariable Cox proportional hazards regression models were used to test the association of baseline fitness (1985-1986) with dyslipidemia incidence over 25 years (2010-2011) in CARDIA (N=4,898). Modified Poisson regression models were used to examine the association of 20-year change in fitness with dyslipidemia incidence between Years 20 and 25 (n=2,487). Data were analyzed in June 2014 and February 2015.

RESULTS

In adjusted models, the risk of incident low high-density lipoprotein cholesterol (HDL-C); high triglycerides; and high low-density lipoprotein cholesterol (LDL-C) was significantly lower, by 9%, 16%, and 14%, respectively, for each 2.0-minute increase in baseline treadmill endurance. After additional adjustment for baseline trait level, the associations remained significant for incident high triglycerides and high LDL-C in the total population and for incident high triglycerides in both men and women. In race-stratified models, these associations appeared to be limited to whites. In adjusted models, change in fitness did not predict 5-year incidence of dyslipidemias, whereas baseline fitness significantly predicted 5-year incidence of high triglycerides.

CONCLUSIONS

Our findings demonstrate the importance of cardiorespiratory fitness in young adulthood as a risk factor for developing dyslipidemias, particularly high triglycerides, during the transition to middle age.

Mass spectral analysis of urine proteomic profiles of dairy cows suffering from clinical ketosis

BACKGROUND

Ketosis is an important metabolic disorder in dairy cows during the transition period. The urine proteomics of ketosis has not been investigated using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS).

OBJECTIVE

The aim is to determine differences between urine proteomic profiles of healthy cows and those with clinical ketosis, and facilitate studies of the underlying physiological and biochemical mechanisms that lead to liver pathology in ketosis.

ANIMALS AND METHODS

We analyzed the urine samples of 20 cows with clinical ketosis (group 1) and 20 control cows (group 2) using SELDI-TOF-MS.

RESULTS

Thirty-nine peptide peaks differed between both groups. Polypeptides corresponding to 26 of these differential peptide peaks were identified using the SWISS-PROT protein database. We found that the peaks of 11 distinct polypeptides from the urine samples of the ketosis group were significantly reduced, compared with those of the control group as based on the Wilcoxon rank sum test. Among these were VGF (non-acronymic) protein, amyloid precursor protein, serum amyloid A (SAA), fibrinogen, C1INH, apolipoprotein C-III, cystatin C, transthyretin, hepcidin, human neutrophil peptides, and osteopontin.

CONCLUSION

These proteins may represent novel biomarkers of the metabolic changes that occur in dairy cows with ketosis. Our results will help to better understand the physiological changes and pathogenesis observed in cows with ketosis.

CLINICAL IMPORTANCE

The SELDI-TOF-MS can be used to understand the physiological and biochemical mechanisms of ketosis and identify biomarkers of the disease.

A cross-sectional study of low physical fitness, self-rated fitness and psychosocial factors in a sample of Finnish 18- to 64-year-old men

Background

The biological risk factors of inactivity and poor cardiorespiratory fitness are well established. However, risk groups are hard to reach and they may have misperceptions of their need for change. This study explored self-ratings of physical fitness (PF) and the relationship between objectively estimated physical fitness (PFI) and psychosocial factors among Finnish men of working-age.

Methods

Cross-sectional data on 899 Finnish men (aged 18–64) were collected in 2011. Health- related physical fitness was evaluated with a physical fitness index calculated from the results of selected fitness tests. The men were subsequently classified into three groups: low, moderate and high PFI. Psychosocial factors and self-rated fitness were elicited in the questionnaire. The data were analysed with crosstabulations, chi square-test and logistic regression analysis.

Results

One-fifth of the participants had low PFI. Forty-five per cent of the low-fit middle-aged (35–49 years) men self-reported poor PF, while 80 per cent of the younger (18–34 years) low-fit men self-reported moderate or good PF. The health benefits and recommended dose of physical activity were well known in all the PFI categories. The low-fit men were health conscious, but lacked adequate exercise skills, self-efficacy and social support. However, logistic regressions revealed that, in the younger men, likelihood of better knowledge was not related to higher PFI. Among the 50-to-64-year-old men, high PFI was not associated with a higher social support.

Conclusions

Poor exercise skills, self-efficacy and social support were related to low PFI. Physical activity promotion for low-fit men should take into account age differences in the relationship between psychosocial factors and physical fitness. Thus, new and effective ways to establish social support and motivation for physical activity among low-fit men in all working-age groups are needed. Further research is also warranted on whether estimation of PFI could be used as a practical health counselling tool.

Does cardiorespiratory fitness modify the association between birth weight and insulin resistance in adult life?

Objective

Lower birth weight is associated with higher insulin resistance in later life. The aim of this study was to determine whether cardiorespiratory fitness modifies the association of birth weight with insulin resistance in adults.

Methods

The subjects were 379 Japanese individuals (137 males, 242 females) aged 20–64 years born after 1943. Insulin resistance was assessed using a homeostasis model assessment of insulin resistance (HOMA-IR), which is calculated from fasting blood glucose and insulin levels. Cardiorespiratory fitness (maximal oxygen uptake, VO₂max) was assessed by a maximal graded exercise test on a cycle ergometer. Birth weight was reported according to the Maternal and Child Health Handbook records or the subject’s or his/her mother’s memory.

Results

The multiple linear regression analysis revealed that birth weight was inversely associated with HOMA-IR (β = −0.141, p = 0.003), even after adjustment for gender, age, current body mass index, mean blood pressure, triglycerides, HDL cholesterol, and smoking status. Further adjustments for VO₂max made little difference in the relationship between birth weight and HOMA-IR (β = −0.148, p = 0.001), although VO₂max (β = −0.376, p<0.001) was a stronger predictor of HOMA-IR than birth weight.

Conclusions

The results showed that the association of lower birth weight with higher insulin resistance was little modified by cardiorespiratory fitness in adult life. However, cardiorespiratory fitness was found to be a stronger predictor of insulin resistance than was birth weight, suggesting that increasing cardiorespiratory fitness may have a much more important role in preventing insulin resistance than an individual’s low birth weight.

Impact of fitness versus obesity on routinely measured cardiometabolic risk in young, healthy adults

Obesity demonstrates a direct relation with cardiovascular risk and all-cause mortality, while cardiorespiratory fitness demonstrates an inverse relation. In clinical practice, several cardiometabolic (CM) risk factors are commonly measured to gauge cardiovascular risk, but the interaction between fitness and obesity with regard to CM risk has not been fully explored. In this study, 2,634 Brazilian adults referred for employer-sponsored heath exams were assessed. Obesity was defined as body mass index >30 kg/m(2) or waist circumference >102 cm in men or >88 cm in women when body mass index was 25 to 30 kg/m(2). Fitness was quantified by stage achieved on an Ellestad treadmill stress test, with those completing stage 4 considered fit. Hepatic steatosis was determined by ultrasound. CM risk factors were compared after stratifying patients into 4 groups: fit and normal weight, fit and obese, unfit and normal weight, and unfit and obese. Approximately 22% of patients were obese; 12% were unfit. Fitness and obesity were moderately correlated (ρ = 0.38 to 0.50). The sample included 6.5% unfit and normal-weight subjects and 16% fit and obese subjects. In overweight and obese patients, fitness was negatively associated with CM risk (p <0.01 for all values). In fit patients, increasing body mass index was positively associated with CM risk (p <0.01 for all values). In instances of discordance between fitness and obesity, obesity was the stronger determinant of CM risk. In conclusion, fitness and obesity are independently associated with CM risk. The effects of fitness and obesity are additive, but obesity is more strongly associated with CM risk when fitness and obesity are discordant. These findings underscore the need for weight loss in obese patients and suggest an unmeasured benefit of fitness.