Age-related change in peak oxygen uptake and change of cardiovascular risk factors. The HUNT Study.

BACKGROUND: Large longitudinal studies on change in directly measured peak oxygen uptake (VO2peak) is lacking, and its significance for change of cardiovascular risk factors is uncertain. We aimed to assess ten-year change in VO2peak and the influence of leisure-time physical activity (LTPA), and the association between change in VO2peak and change in cardiovascular risk factors. METHODS AND RESULTS: A healthy general population sample had their VO2peak directly measured in two (n = 1431) surveys of the Nord-Trøndelag Health Study (HUNT3; 2006-2008 and HUNT4; 2017-19). Average ten-year decline in VO2peak was non-linear and progressed from 3% in the third to about 20% in the eight decade in life and was more pronounced in men. The fit linear mixed models including an additional 2,933 observations from subjects participating only in HUNT3 showed similar age-related decline. Self-reported adherence to LTPA recommendations was associated with better maintenance of VO2peak, with intensity seemingly more important than minutes of LTPA with higher age. Adjusted linear regression analyses showed that one mL/kg/min better maintenance of VO2peak was associated with favorable changes of individual cardiovascular risk factors (all p ≤ 0.002). Using logistic regression one mL/kg/min better maintenance of VO2peak was associated with lower adjusted odds ratio of hypertension (0.95 95% CI 0.92 to 0.98), dyslipidemia (0.92 95% CI 0.89 to 0.94), and metabolic syndrome (0.86 95% CI 0.83 to 0.90) at follow-up. CONCLUSIONS: Although VO2peak declines progressively with age, performing LTPA and especially high-intensity LTPA is associated with less decline. Maintaining VO2peak is associated with an improved cardiovascular risk profile.

Left Atrial Volume, Cardiorespiratory Fitness, and Diastolic Function in Healthy Individuals: The HUNT Study, Norway.

Background Left atrial (LA) size and cardiorespiratory fitness (CRF) are predictors of future cardiovascular events in high-risk populations. LA dilatation is a diagnostic criterion for left ventricular diastolic dysfunction. However, LA is dilated in endurance athletes with high CRF, but little is known about the association between CRF and LA size in healthy, free-living individuals. We hypothesized that in a healthy population, LA size was associated with CRF and leisure-time physical activity, but not with echocardiographic indexes of left ventricular diastolic dysfunction. Methods and Results In this cross-sectional study from HUNT (Nord-Trøndelag Health Study), 107 men and 138 women, aged 20 to 82 years, without hypertension, cardiovascular, pulmonary, or malignant disease participated. LA volume was assessed by echocardiography and indexed to body surface area LAVI (left atrial volume index). CRF was measured as peak oxygen uptake (VO2peak) using ergospirometry, and percent of age- and-sex-predicted VO2peak was calculated. Indexes of left ventricular diastolic dysfunction were assessed in accordance with latest recommendations. LAVI was >34 mL/m2 in 39% of participants, and LAVI was positively associated with VO2peak and percentage of age- and-sex-predicted VO2peak (ß [95% CI], 0.11 [0.06-0.16] and 0.18 [0.09-0.28], respectively) and weighted minutes of physical activity per week (ß [95% CI], 0.01 [0.003-0.015]). LAVI was not associated with other indexes of left ventricular diastolic dysfunction. There was an effect modification between age and VO2peak/percentage of age- and-sex-predicted VO2peak showing higher LAVI with advanced age and higher VO2peak/percentage of age- and-sex-predicted VO2peak as presented in prediction diagrams. Conclusions Interpretation of LAVI as a marker of diastolic dysfunction should be done in relation to age-relative CRF. Studies on the prognostic value of LAVI in fit subpopulations are needed.

ADHD, comorbid disorders and psychosocial functioning: How representative is a child cohort study? Findings from a national patient registry.

BACKGROUND: Cohort studies often report findings on children with Attention Deficit Hyperactivity Disorder (ADHD) but may be biased by self-selection. The representativeness of cohort studies needs to be investigated to determine whether their findings can be generalised to the general child population. The aim of the present study was to examine the representativeness of child ADHD in the Norwegian Mother and Child Cohort Study (MoBa). METHODS: The study population was children born between January 1, 2000 and December 31, 2008 registered with hyperkinetic disorders (hereafter ADHD) in the Norwegian Patient Registry during the years 2008-2013, and two groups of children with ADHD were identified in: 1. MoBa and 2. The general child population. We used the multiaxial International Classification of Diseases (ICD-10) and compared the proportions of comorbid disorders (axes I-III), abnormal psychosocial situations (axis V) and child global functioning (axis VI) between these two groups. We also compared the relative differences in the multiaxial classifications for boys and girls and for children with/without axis I comorbidity, respectively in these two groups of children with ADHD. RESULTS: A total of 11 119 children were registered with ADHD, with significantly fewer in MoBa (1.45%) than the general child population (2.11%), p < 0.0001. The proportions of comorbid axis I, II, and III disorders were low, with no significant group differences. Compared with the general child population with ADHD, children with ADHD in MoBa were registered with fewer abnormal psychosocial situations (axis V: t = 7.63, p < .0001; d = -.18) and better child global functioning (axis VI: t = 7.93, p < 0.0001; d = .17). When analysing relative differences in the two groups, essentially the same patterns were found for boys and girls and for children with/without axis I comorbidity. CONCLUSIONS: Self-selection was found to affect the proportions of ADHD, psychosocial adversity and child global functioning in the cohort. However, the differences from the general population were small. This indicates that studies on ADHD and multiaxial classifications in MoBa, as well as other cohort studies with similar self-selection biases, may have reasonable generalisability to the general child population.

Non-Smoking Tobacco Affects Endothelial Function in Healthy Men in One of the Largest Health Studies Ever Performed; The Nord-Trøndelag Health Study in Norway; HUNT3.

BACKGROUND: Oral tobacco (snuff) is taking a large market share in Scandinavia, especially with young users. However, long-term health effects are unknown. Small studies show association between snuff and reduced endothelial function, representing an early stage of vascular injury that often precedes manifest cardiovascular disease by several years. We therefore determined the associations between snuff and endothelial function in a large sample of healthy Norwegian men. METHODS AND DESIGN: In the Fitness substudy of the Nord-Trøndelag Health Study (HUNT3), endothelial function was measured by flow-mediated dilation (FMD). Aerobic fitness was measured by peak oxygen uptake (VO2peak). A cross-sectional design including 1 592 self-reported healthy men compared these observations with records of present tobacco use, standard cardiovascular risk factors, and socioeconomic status, using general linear models. RESULTS: FMD was lower in snuff users (FMD: 4.12%, 3.63, 4.61) compared to non-users (FMD: 4.52%, 4.27, 4.78) after adjustment for age (difference: -0.57%, -1.12, -0.01). After further adjustment for potential confounders, FMD still tended to be lower in snuff users than in non-users (difference: -0.53%, -1.09, 0.02). This difference was even more pronounced in the inactive snuff users (-0.83%, -1.59, -0.06) and in the low fit snuff users (-0.74%, CI -0.55, 0.079). CONCLUSIONS: Oral tobacco is associated with a tendency towards reduced endothelial function, indicating vascular changes that precede cardiovascular disease. The strongest associations were found in men with low physical activity or reduced aerobic fitness.

Cardiovascular risk factors have larger impact on endothelial function in self-reported healthy women than men in the HUNT3 Fitness study.

BACKGROUND: Several studies suggest that cardiovascular risk factors comprising the metabolic syndrome have larger effects on the development of cardiovascular disease in women than in men. A recent study in self-reported healthy subjects demonstrated a marked gender difference in endothelial dysfunction that may be an important precursor of manifest cardiovascular disease. The aim of the present study was to determine whether the association between endothelial function and cardiovascular risk factors is different in self-reported healthy women compared to self-reported healthy men. METHODS AND RESULTS: Associations between endothelial function (flow mediated dilation, FMD, of the brachial artery measured by ultrasound), anthropometric variables, peak oxygen uptake (VO2peak), blood pressure, serum lipids, blood glucose and a questionnaire on general health and lifestyle including smoking status were studied by logistic and linear regression in 2 528 women and 2 211 men aged 20-89 years, free from self-reported cardiovascular disease. In women with hyperglycemia, endothelial dysfunction (FMD ≤0%) occurred twice as frequently as in male counterparts. The presence of the metabolic syndrome, high blood pressure and low VO2peak increased the prevalence of endothelial dysfunction more in women than in men. CONCLUSION: Endothelial dysfunction is more strongly associated with cardiovascular risk factors in self-reported healthy women than in self-reported healthy men. This finding could explain why the metabolic syndrome, and especially hyperglycemia, is associated with higher cardiovascular risk and a worse prognosis in women.

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.

Age and gender differences of endothelial function in 4739 healthy adults: the HUNT3 Fitness Study.

AIMS: Endothelial dysfunction is an important marker for prognosis in patients with coronary heart disease. However, there are no reference values for endothelial function in a healthy population. Our aim was to determine the distribution of flow-mediated dilation (FMD) values by gender and age in healthy adults. METHODS: FMD was measured by ultrasound during reactive hyperaemia in the brachial artery of 4739 adults aged 20-89 years, who were free from self-reported cardiovascular or pulmonary disease. Differences in FMD across age and gender were analysed by multiple linear regression. RESULTS: Total mean ± SD FMD was 4.8 ± 4.2%, with corresponding estimates of 4.3 ± 3.9% for men and 5.3 ± 4.5% for women (p < 0.001). In total, 17% had FMD ≤0%, indicating endothelial dysfunction. FMD decreased with increasing age in both genders up to 70 years for men and 80 for women (p < 0.001). In women, age-related decline in FMD was steepest after age 45; in men, a steady decline after age 30. In men 80 years and older, FMD was higher than in men aged 50-79 years. CONCLUSIONS: The distribution of FMD in this study is representative of the respective age and gender groups of a healthy population and may be a useful reference for future studies. The high proportion of endothelial dysfunction came as a surprise. Its age and gender distribution suggest that FMD ≤0% precedes cardiovascular disease and that it may be a powerful non-invasive biomarker for identifying high-risk individuals.

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.

A prospective population study of resting heart rate and peak oxygen uptake (the HUNT Study, Norway).

OBJECTIVES: We assessed the prospective association of resting heart rate (RHR) at baseline with peak oxygen uptake (VO(2peak)) 23 years later, and evaluated whether physical activity (PA) could modify this association. BACKGROUND: Both RHR and VO(2peak) are strong and independent predictors of cardiovascular morbidity and mortality. However, the association of RHR with VO(2peak) and modifying effect of PA have not been prospectively assessed in population studies. METHODS: In 807 men and 810 women free from cardiovascular disease both at baseline (1984-86) and follow-up 23 years later, RHR was recorded at both occasions, and VO(2peak) was measured by ergospirometry at follow-up. We used Generalized Linear Models to assess the association of baseline RHR with VO(2peak), and to study combined effects of RHR and self-reported PA on later VO(2peak). RESULTS: There was an inverse association of RHR at baseline with VO(2peak) (p<0.01). Men and women with baseline RHR greater than 80 bpm had 4.6 mL.kg(-1).min(-1) (95% confidence interval [CI], 2.8 to 6.3) and 1.4 mL.kg(-1).min(-1) (95% CI, -0.4 to 3.1) lower VO(2peak) at follow-up compared with men and women with RHR below 60 bpm at baseline. We found a linear association of change in RHR with VO(2peak) (p=0.03), suggesting that a decrease in RHR over time is likely to be beneficial for cardiovascular fitness. Participants with low RHR and high PA at baseline had higher VO(2peak) than inactive people with relatively high RHR. However, among participants with relatively high RHR and high PA at baseline, VO(2peak) was similar to inactive people with relatively low RHR. CONCLUSION: RHR is an important predictor of VO(2peak), and serial assessments of RHR may provide useful and inexpensive information on cardiovascular fitness. The results suggest that high levels of PA may compensate for the lower VO(2peak) associated with a high RHR.

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-training intervention studies in competitive swimming.

Competitive swimming has a long history and is currently one of the largest Olympic sports, with 16 pool events. Several aspects separate swimming from most other sports such as (i) the prone position; (ii) simultaneous use of arms and legs for propulsion; (iii) water immersion (i.e. hydrostatic pressure on thorax and controlled respiration); (iv) propulsive forces that are applied against a fluctuant element; and (v) minimal influence of equipment on performance. Competitive swimmers are suggested to have specific anthropometrical features compared with other athletes, but are nevertheless dependent on physiological adaptations to enhance their performance. Swimmers thus engage in large volumes of training in the pool and on dry land. Strength training of various forms is widely used, and the energetic systems are addressed by aerobic and anaerobic swimming training. The aim of the current review was to report results from controlled exercise training trials within competitive swimming. From a structured literature search we found 17 controlled intervention studies that covered strength or resistance training, assisted sprint swimming, arms-only training, leg-kick training, respiratory muscle training, training the energy delivery systems and combined interventions across the aforementioned categories. Nine of the included studies were randomized controlled trials. Among the included studies we found indications that heavy strength training on dry land (one to five repetitions maximum with pull-downs for three sets with maximal effort in the concentric phase) or sprint swimming with resistance towards propulsion (maximal pushing with the arms against fixed points or pulling a perforated bowl) may be efficient for enhanced performance, and may also possibly have positive effects on stroke mechanics. The largest effect size (ES) on swimming performance was found in 50 m freestyle after a dry-land strength training regimen of maximum six repetitions across three sets in relevant muscle-groups (ES 1.05), and after a regimen of resisted- and assisted-sprint training with elastic surgical tubes (ES 1.21). Secondly, several studies suggest that high training volumes do not pose any immediate advantage over lower volumes (with higher intensity) for swim performance. Overall, very few studies were eligible for the current review although the search strategy was broad and fairly liberal. The included studies predominantly involved freestyle swimming and, overall, there seems to be more questions than answers within intervention-based competitive swimming research. We believe that this review may encourage other researchers to pursue the interesting topics within the physiology of competitive swimming.

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.

Estimating V·O 2peak from a nonexercise prediction model: the HUNT Study, Norway.

PURPOSE: Cardiorespiratory fitness is suggested to be an important marker of cardiovascular risk but is rarely evaluated in health care settings. In the present study, directly measured peak oxygen uptake (V·O 2peak) from a diverse population of 4637 healthy participants were used to develop and cross-validate a new nonexercise regression model of cardiorespiratory fitness for men and women. METHODS AND RESULTS: Multivariable regression analysis was used to develop a nonexercise model of cardiorespiratory fitness for men and women separately with V·O 2peak as the outcome. In the final models, 2067 men (mean age = 48.8 yr) and 2193 women (mean age = 47.9 yr) were included, respectively. Cross-validation of the models was done by standard data splitting procedures with evaluation of constant error and total error of a model developed on one sample and cross-validated on another sample. Age, waist circumference, leisure time physical activity, and resting HR, successively, were the most potent predictors of V·O 2peak for both men and women. Together, 61% and 56% of variance in V·O 2peak, for men and women, respectively, were explained by the full models. SEE was 5.70 and 5.14 for the models including men and women, respectively. CONCLUSIONS: The nonexercise regression model developed in the present study was fairly accurate in predicting V·O 2peak in this healthy population of men and women. The model might be generalized to other healthy populations and might be a valid tool for a rough assessment of cardiorespiratory fitness in an outpatient setting.

Physical activity as a long-term predictor of peak oxygen uptake: the HUNT Study.

INTRODUCTION: A physically active lifestyle and a relatively high level of cardiorespiratory fitness are important for longevity and long-term health. No population-based study has prospectively assessed the association of physical activity levels with long-term peak oxygen uptake (VO(2peak)). METHODS: 1843 individuals (906 women and 937 men) who were between 18 and 66 yr at baseline and were free from known lung or heart diseases at both baseline (1984-1986) and follow-up (2006-2008) were included in the study. Self-reported physical activity was recorded at both occasions, and VO(2peak) was measured at follow-up. The association of physical activity levels and VO(2peak) was adjusted for age, level of education, smoking status, and weight change from baseline to follow-up, using ANCOVA statistics. RESULTS: The level of physical activity at baseline was strongly associated with VO(2peak) at follow-up 23 yr later in both men and women (Ptrends < 0.001). Compared with individuals who were inactive at baseline, women and men who were highly active at baseline had higher (3.3 and 4.6 mL·kg(-1)·min(-1)) VO(2peak) at follow-up. Women who were inactive at baseline but highly active at follow-up had 3.7 mL·kg(-1)·min(-1) higher VO(2peak) compared with women who were inactive both at baseline and at follow-up. The corresponding comparison in men showed a difference of 5.2 mL·kg(-1)·min(-1) (95% confidence interval = 3.1-7.3) in VO(2peak). CONCLUSIONS: Physical activity level at baseline was positively associated with directly measured cardiorespiratory fitness (VO(2peak)) 23 yr later. People who changed from low to high activity during the observation period had substantially higher V˙O(2peak) at follow-up compared with people whose activity remained low.

Peak oxygen uptake and cardiovascular risk factors in 4631 healthy women and men.

INTRODUCTION: Many studies suggest that cardiorespiratory fitness, measured as peak oxygen uptake (VO2peak), may be the single best predictor of cardiovascular morbidity and premature cardiovascular mortality. However, current reference values are either estimates of oxygen uptake or come from small studies, mainly of men. Therefore, the aims of this study were to directly measure VO2peak in healthy adult men and women and to assess the association with cardiovascular risk factor levels. METHODS: A cross-sectional study of 4631 volunteering, free-living Norwegian men (n = 2368) and women (n = 2263) age 20-90 yr. The data collection was from June 2007 to June 2008. Participants were free from known pulmonary or cardiovascular disease. VO2peak was measured by ergospirometry during treadmill running. Associations (odds ratios, OR) with unfavorable levels of cardiovascular risk factors and a cluster of cardiovascular risk factors were assessed by logistic regression analysis. RESULTS: Overall, mean VO2peak was 40.0 ± 9.5 mL·kg(-1)·min(-1). Women below the median VO2peak (<35.1 mL·kg(-1)·min(-1)) were five times (OR = 5.4, 95% confidence interval = 2.3-12.9) and men below the median (<44.2 mL·kg(-1)·min(-1)) were eight times (OR = 7.9, 95% confidence interval = 3.5-18.0) more likely to have a cluster of cardiovascular risk factors compared to those in the highest quartile of VO2peak (≥40.8 and ≥50.5 mL·kg(-1)·min(-1) in women and men, respectively). Each 5-mL·kg(-1)·min(-1) lower VO2peak corresponded to ∼56% higher odds of cardiovascular risk factor clustering. CONCLUSIONS: These data represent the largest reference material of objectively measured VO2peak in healthy men and women age 20-90 yr. Even in people considered to be fit, VO2peak was clearly associated with levels of conventional cardiovascular risk factors.

Strength training versus aerobic interval training to modify risk factors of metabolic syndrome.

Metabolic syndrome is characterized by central obesity, elevated blood pressure, high fasting glucose and triglyceride levels, and low HDL levels. Regular physical activity can improve the metabolic profile and reduce the risks of cardiovascular diseases and premature mortality. However, the optimal training regime to treat metabolic syndrome and its associated cardiovascular abnormalities remains undefined. Forty-three participants with metabolic syndrome were randomized to one of the following groups: aerobic interval training (AIT; n = 11), strength training (ST; n = 11), a combination of AIT and ST (COM; n = 10) 3 times/wk for 12 wk, or control (n = 11). Risk factors comprising metabolic syndrome were evaluated before and after the intervention. Waist circumference (in cm) was significantly reduced after AIT [95% confidence interval (CI): -2.5 to -0.04], COM (95% CI: -2.11 to -0.63), and ST (95% CI: -2.68 to -0.84), whereas the control group had an increase in waist circumference (95% CI: 0.37-2.9). The AIT and COM groups had 11% and 10% increases in peak O2 uptake, respectively. There were 45% and 31% increases in maximal strength after ST and COM, respectively. Endothelial function, measured as flow-mediated dilatation (in %), was improved after AIT (95% CI: 0.3-3), COM (95% CI: 0.3-3), and ST (95% CI: 1.5-4.5). There were no changes in body weight, fasting plasma glucose, or HDL levels within or between the groups. In conclusion, all three training regimes have beneficial effects on physiological abnormalities associated with metabolic syndrome.

Combined strength and endurance training in competitive swimmers.

A combined intervention of strength and endurance training is common practice in elite swimming training, but the scientific evidence is scarce. The influences between strength and endurance training have been investigated in other sports but the findings are scattered. Some state the interventions are negative to each other, some state there is no negative relationship and some find bisected and supplementary benefits from the combination when training is applied appropriately. The aim of this study was to investigate the impact of a combined intervention among competitive swimmers. 20 subjects assigned to a training intervention group (n = 11) or a control group (n = 9) from two different teams completed the study. Anthropometrical data, tethered swimming force, land strength, performance in 50m, 100m and 400m, work economy, peak oxygen uptake, stroke length and stroke rate were investigated in all subjects at pre- and post-test. A combined intervention of maximal strength and high aerobic intensity interval endurance training 2 sessions per week over 11 weeks in addition to regular training were used, while the control group continued regular practice with their respective teams. The intervention group improved land strength, tethered swimming force and 400m freestyle performance more than the control group. The improvement of the 400m was correlated with the improvement of tethered swimming force in the female part of the intervention group. No change occurred in stroke length, stroke rate, performance in 50m or 100m, swimming economy or peak oxygen uptake during swimming. Two weekly dry-land strength training sessions for 11 weeks increase tethered swimming force in competitive swimmers. This increment further improves middle distance swimming performance. 2 weekly sessions of high- intensity interval training does not improve peak oxygen uptake compared with other competitive swimmers. Key pointsTwo weekly sessions of dry land strength training improves the swimming force.Two weekly sessions of high-intensity endurance training did not cause improved endurance capacity.It may seem that dry land strength training can improve middle distance performance.