Circulating microRNAs and aerobic fitness--the HUNT-Study.

Aerobic fitness, measured as maximal oxygen uptake (VO2max), is a good indicator of cardiovascular health, and a strong predictor of cardiovascular mortality. Biomarkers associated with low VO2max may therefore represent potential early markers of future cardiovascular disease (CVD). The aim of this study was to assess whether circulating microRNAs (miRs) are associated with VO2max-level in healthy individuals. In a screening study, 720 miRs were measured in serum samples from healthy individuals (40-45 yrs) with high (n = 12) or low (n = 12) VO2max matched for gender, age and physical activity. Candiate miRs were validated in a second cohort of subjects with high (n = 38) or low (n = 38) VO2max. miR-210 and miR-222 were found to be higher in the low VO2max-group (p<0.05). In addition, miR-21 was increased in male participants with low VO2max (p<0.05). There were no correlations between traditional risk factors for CVD (blood pressure, cholesterol, smoking habit, or obesity) and miR-21, miR-210 and miR-222. DIANA-mirPath identified 611 potential gene-targets of miR-21, miR-210 and miR-222, and pathway analysis indicated alterations in several important signaling systems in subjects with low VO2max. Potential bias involve that blood was collected from non-fasting individuals, and that 8 performed exercise within 24 h before sampling. In conclusion, we found that miR-210, miR-21, and miR-222 were increased in healthy subjects with low VO2max. The lack of association between these three miRs, and other fitness related variables as well as traditional CVD risk factors, suggests that these miRs may have a potential as new independent biomarkers of fitness level and future CVD.

Peak oxygen uptake and physical activity in 13- to 18-year-olds: the Young-HUNT study.

PURPOSE: The present study describes the distribution of cardiorespiratory fitness (VO2peak) in a large sample of healthy adolescents and the associations between VO2peak, self-reported physical activity, and a selection of conventional markers for future cardiovascular health. METHODS: In a substudy of the Young-HUNT study in Norway, 570 adolescents (289 girls and 281 boys) 13­18 yr. old were tested for directly measured VO2peak. Blood pressure, resting heart rate, height, weight, and waist circumference was measured by standardized procedures. Data about physical activity and pubertal development were obtained using self-administered questionnaires. General linear modeling and ANOVA were used to examine the relationships between VO2peak and age, physical activity, and cardiovascular risk factors. RESULTS: The mean T SD VO2peak was 183.9 +/- 24.6 mL x kg(-0.67) x min(-1) (49.2 mL x kg(-0.67) x min(-1)) in girls and 235.1 +/- 35.3 mL x kg(-0.67) x min(-1) (59.5 mL x kg(-0.67) x min(-1)) in boys. Absolute VO2peak (L x min(-1)) was consistently higher in older age groups in both sexes (P trend < 0.001). VO2peak allometrically scaled to body mass (mL x kg(-0.67) x min(-1)) was similar across the age groups in girls (i.e., difference between 13- to 14-yr-olds and 17- to 18-yr-olds = -3.2 mL x kg(-0.67) x min(-1), 95% confidence interval = 3.8 to -10.1) and slightly higher in the older age groups in boys (i.e., difference between 13- to 14-yr-olds and 15- to 16-yr-olds = -31.0 mL x kg(-0.67) x min(-1), 95% confidence interval = -22.0 to -40.1). Physical activity was positively associated with VO2peak in all sex and age groups. Quartiles of VO2peak were inversely associated with resting heart rate (P trend = 0.004) in both sexes and body mass index (P trend = 0.004) and waist circumference (P trend = 0.006) in boys. CONCLUSION: Although VO2peak was generally high across the age groups, VO2peak was higher in physically active adolescents of both sexes and physical activity in accordance with the recommended level may be sufficient to maintain or even increase VO2peak through adolescence.

Serum levels of choline-containing compounds are associated with aerobic fitness level: the HUNT-study.

BACKGROUND: Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of people at risk is continuously growing. New methods for early risk prediction are therefore needed to actuate prevention strategies before the individuals are diagnosed with CVD. Several studies report that aerobic fitness level, measured as maximal oxygen uptake (VO(2max)), is the single best predictor of future CVD mortality in healthy people. Based on this, we wanted to study differences between healthy individuals with a large difference in VO(2max)-level to identify new biomarkers of low aerobic fitness that may also have potential as early biomarkers of CVD risk. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples from 218 healthy individuals with a low VO(2max) (n = 108, 63 women) or high VO(2max) (n = 110, 64 women) were analysed with MR metabolomics. In addition, standard clinical-chemical analyses for glucose, lipids, liver enzymes, micro-CRP, and colorimetric analysis on circulating choline were performed. Individuals in the low VO(2max)-group had increased serum levels of free choline, decreased phosphatidylcholine, increased glucose and decreased unsaturated fatty acids compared to the individuals in the high VO(2max)-group. CONCLUSIONS/SIGNIFICANCE: Aerobic fitness dependent differences in serum levels of free choline and phosphatidylcholine are observed. They should be further studied as potential early markers of CVD risk.

Exercise patterns and peak oxygen uptake in a healthy population: the HUNT study.

PURPOSE: The objective of this study is to examine how different approaches of the current exercise recommendations for adults associate with VO(2peak) in a large healthy population. We further examined how a lower duration than recommended, if performed at very vigorous intensity, was related to VO(2peak). METHODS: A total of 4631 healthy adults age 19-89 yr (2263 men and 2368 women) were tested for VO(2peak) (mean = 44.3 and 35.9 mL.kg(-1).min(-1) for men and women, respectively). Information on exercise habits was collected through a questionnaire, including questions on frequency, duration, and relative intensity (Borg scale 6-20). A general linear model was applied to assess the associations between physical activity and VO(2peak). RESULTS: VO(2peak) did not differ considerably between people who reported to exercise ≥ 150 min.wk(-1) (average = 216 min.wk(-1) , VO(2peak) = 45.2 and 36.5 mL.kg(-1).min(-1)for men and women, respectively) with moderate intensity and people who reported 75-149 min.wk(-1) (average = 112.5 min.wk(-1) , VO(2peak) = 47.5 and 37.3 mL.kg(-1).min(-1) for men and women) with vigorous intensity, but it was higher than that in people who reported inactivity (VO(2peak) = 40.1 and 32.3 mL.kg(-1).min(-1)for men and women) or low-intensity exercise (VO(2peak) = 41.2 and 40.1 mL.kg(-1).min(-1)for men and women). Reporting exercise at very vigorous intensity but with a duration of less than 75 min.wk(-1) (average = 49 min.wk(-1) ) was associated with a VO(2peak) that was similarly high (47.6 and 36.7 mL.kg(-1).min(-1) for men and women). CONCLUSION: Our findings support current recommendations by showing that exercise of both "moderate intensity-long duration" and "vigorous intensity-short duration" was associated with similarly high VO(2peak). Our results also suggest that exercising at very vigorous intensity may be beneficial for VO(2peak) even with considerably lower total exercise time than expressed in today's recommendations.