The protective effect of good physical fitness when young on the risk of impaired glucose tolerance when old

Relevance of Physical Fitness and Cardiovascular Disease Risk

BACKGROUND

This study explored the relationship between fitness performance, in terms of muscular endurance and cardiorespiratory fitness (CRF), and cardiovascular disease (CVD) risk.Methods and Results:The study was performed on 51,500 eligible participants from the Republic of China Armed Forces. Participants were divided into 4 groups (obese or non-obese males and females). Correlations between the Framingham risk score of coronary artery disease (FRS-CAD) and physical fitness (evaluated using 2-min push-ups, 2-min sit-ups, and 3,000-m non-weight-bearing running tests) were calculated using univariate and multivariate linear regression, as well as an extended model that adjusted for covariates. In males, regardless of obesity status, there were significant negative correlations between quartiles of fitness performance and the FRS-CAD (P<0.001) in the unadjusted and adjusted models, except for the sit-up test in the model adjusted for age, serum uric acid, hemoglobin, creatinine, current drinking, betel nut chewing, and running test speed. FRS-CAD was lower for higher quartiles of physical fitness (P for trend <0.001) in male participants. However, no significant relationship between fitness performance and FRS-CAD was observed in females, regardless of obesity status.

CONCLUSIONS

The findings highlighted a substantial association between fitness performance and FRS-CAD, especially in adult males. Muscular endurance and CRF may be a convenient risk evaluation tool for future CVD risk in the general, healthy, young to middle-aged male population in Taiwan.

Physical activity is associated with lower insulin and C-peptide during glucose challenge in children and adolescents with family background of diabetes

AIMS

Children and adolescents with a family history of diabetes are at increased risk of overweight, but little is known about the potentially beneficial effects of physical activity on these children. The objective of this study was to investigate the association between moderate to vigorous physical activity (MVPA) and metabolic and inflammatory risks in children and adolescents with a family background of Type 1 diabetes or gestational diabetes.

METHODS

Valid MVPA measurements, made with accelerometers, were available from 234 participants (median age, 10.2 years) who had a first-degree relative with either Type 1 or gestational diabetes. Anthropometric and metabolic measurements were made and cytokines measured, and were correlated with MVPA measurements, with stepwise adjustment for confounding factors, in a cross-sectional analysis.

RESULTS

MVPA was negatively associated with insulin and C-peptide during challenge with an oral glucose tolerance test. MVPA was also significantly positively associated with the insulin sensitivity index, whereas no consistently significant associations were found between MVPA and BMI, blood pressure or cytokine levels.

DISCUSSION

Our findings indicate that physical activity may have beneficial effects on insulin and C-peptide metabolism in children and adolescents with a family background of diabetes, but show no evidence of a protective association with other health-related outcomes.

Exercise training alters DNA methylation patterns in genes related to muscle growth and differentiation in mice

The adaptive response of skeletal muscle to exercise training is tightly controlled and therefore requires transcriptional regulation. DNA methylation is an epigenetic mechanism known to modulate gene expression, but its contribution to exercise-induced adaptations in skeletal muscle is not well studied. Here, we describe a genome-wide analysis of DNA methylation in muscle of trained mice (n = 3). Compared with sedentary controls, 2,762 genes exhibited differentially methylated CpGs (P < 0.05, meth diff >5%, coverage >10) in their putative promoter regions. Alignment with gene expression data (n = 6) revealed 200 genes with a negative correlation between methylation and expression changes in response to exercise training. The majority of these genes were related to muscle growth and differentiation, and a minor fraction involved in metabolic regulation. Among the candidates were genes that regulate the expression of myogenic regulatory factors (Plexin A2) as well as genes that participate in muscle hypertrophy (Igfbp4) and motor neuron innervation (Dok7). Interestingly, a transcription factor binding site enrichment study discovered significantly enriched occurrence of CpG methylation in the binding sites of the myogenic regulatory factors MyoD and myogenin. These findings suggest that DNA methylation is involved in the regulation of muscle adaptation to regular exercise training.

Long-term effects of leisure time physical activity on risk of insulin resistance and impaired glucose tolerance, allowing for body weight history, in Danish men

AIMS

To determine if the level of leisure time physical activity (LTPA) in young adulthood in obese and non-obese men reduces the risk of insulin resistance (IR) and impaired glucose tolerance (IGT) in middle age, and if such an effect is explained by the current level of LTPA, or by the body mass index (BMI) history preceding and subsequent to the assessment of LTPA.

METHODS

Longitudinal study of groups of obese and randomly selected non-obese men identified at around age 19, and re-examined at mean ages of 32, 44 and 51. BMI was measured at all four examinations. LTPA was assessed by self-administrated questionnaires at the last three examinations. IR and the presence of IGT was determined by an oral glucose tolerance test at the last examination.

RESULTS

LTPA in young adulthood reduced the risk of IR and IGT in middle age throughout the range of BMI. Adjustment for the BMI history preceding and subsequent to the assessment of LTPA attenuated the association with IR and IGT, but active men remained at low risk of IR and IGT. Adjustment for subsequent and current levels of LTPA, smoking habits, alcohol intake, educational level and family history of diabetes had no notable influence on the results.

CONCLUSION

LTPA appears to reduce the risk of IR and IGT, an effect which is not explained by the current level of physical activity, and only partially explained by the BMI history preceding and subsequent to the assessment of LTPA.

Cardiovascular fitness and physical activity in children with and without impaired glucose tolerance

OBJECTIVE

To examine differences in cardiovascular fitness (VO(2max)) and physical activity levels in overweight Hispanic children with normal glucose tolerance (NGT) vs impaired glucose tolerance (IGT).

PARTICIPANTS

A total of 173 overweight (BMI percentile 97.0 +/- 3.1) Hispanic children ages 8-13 years with a family history of type 2 diabetes.

METHODS

VO(2max) was measured via a maximal effort treadmill test and open circuit spirometry. Physical activity was determined by questionnaire. Glucose tolerance was established by a 2-h oral glucose challenge (1.75 g of glucose/kg body weight). IGT was defined from an oral glucose tolerance test as a 2-h plasma glucose level > or =140 and <200 mg/dl.

RESULTS

IGT was detected in 46 of the 173 participants (approximately 27%); no cases of type 2 diabetes were identified. No significant differences were found between youth with NGT and those with IGT in absolute VO(2max) (2.2 +/- 0.6 vs 2.1 +/- 0.5 l/min), VO(2max) adjusted for gender, age, and body composition (2.2 +/- 0.2 vs 2.1 +/- 0.2 l/min), or recreational physical activity levels (8.7 +/- 8.2 vs 6.9 +/- 6.2 h/week).

CONCLUSION

Overweight Hispanic youth with IGT exhibit similar levels of VO(2max) and physical activity compared to their NGT counterparts. Longitudinal analyses are necessary to determine whether fitness/activity measures contribute significantly to diabetes risk over time in this group.

Vascular risks and management of obesity in children and adolescents

Childhood obesity has reached epidemic proportions in many countries. Pediatric obesity is associated with the development of cardiovascular (CV) risk factors including type 2 diabetes, hypertension, dyslipidemia, and the metabolic syndrome. It is also associated with an increased risk of CV disease (CVD) in adulthood. Moreover, obesity and CVD risk factors in obese youth tend to track into adulthood, further increasing the risk of adult CVD. Consequently, the treatment and prevention of childhood overweight and obesity has become a public health priority. Proper nutrition and increased physical activity are the main focus of these efforts; however, few studies have shown positive results. Treatment options for obesity in youth also include pharmacotherapy and surgery. While pharmacotherapy appears promising, additional evidence is needed, especially with respect to the long-term impact, before it becomes a widespread treatment option in the pediatric population.

[Epidemiology of diabetes and its non-coronary complications]

Diabetes mellitus is among the diseases with great impact on health and society, not only for its high prevalence but also for its chronic complications and high mortality. The most precise method to investigate the prevalence of diabetes is by oral glucose tolerance testing. In Spain, the prevalence of diabetes in the 30-65 year-old population is estimated to be 6.5% among 30-to-65- year old, and 10.3% among the 30-to-89 year-old population. The ratio of known to unknown diabetes ranges from 1:3 to 2:3. The incidence of diabetes mellitus type 2 in Spain is 8/1000 persons per year, and the incidence of type 1 is 11 to 12 cases per 100,000 persons per year. The prevalence of chronic complications varies according to type of diabetes, time since onset and degree of metabolic control: neuropathy 25%, retinopathy 32% and nephropathy 23%. Diabetes is one of the most important causes of death in Spain, occupying third place for women and seventh for men.

The association between physical activity, physical fitness, and type 2 diabetes mellitus

Recent studies have shown that cardiorespiratory fitness--an objective measurement of physical activity--is a strong predictor of type 2 diabetes. Self-reported physical activity is also associated with decreased risk of developing diabetes.

Effects of physical activity on insulin action and glucose tolerance in obesity

PURPOSE

The purpose of this paper is to examine the effect of physical activity on glucose tolerance in relation to obesity.

METHODS

We reviewed current literature, with particular emphasis on randomized clinical trials, to prepare an evidence-based evaluation of the effects of physical activity on glucose intolerance in obesity.

RESULTS

This literature review indicates that physical activity has favorable effects on reducing insulin resistance in obesity and among patients with type 2 diabetes mellitus. Improvement in glucose tolerance is less consistently observed and is related to intensity of exercise, collateral changes in adiposity, the interval between exercise and testing of glucose tolerance, and the baseline severity of glucose intolerance.

CONCLUSION

A review of currently published clinical trial data supports the conclusion that physical activity can reduce insulin resistance and improve glucose intolerance in obesity.