Mathias Ried-Larsen

The effects of physical activity and exercise on brain-derived neurotrophic factor in healthy humans: A review

The purpose of this study was to summarize the effects of physical activity and exercise on peripheral brain‐derived neurotrophic factor (BDNF) in healthy humans. Experimental and observational studies were identified from PubMed, Web of Knowledge, Scopus, and SPORT Discus. A total of 32 articles met the inclusion criteria. Evidence from experimental studies suggested that peripheral BDNF concentrations were elevated by acute and chronic aerobic exercise. The majority of the studies suggested that strength training had no influence on peripheral BDNF. The results from most observational studies suggested an inverse relationship between the peripheral BDNF level and habitual physical activity or cardiorespiratory fitness. More research is needed to confirm the findings from the observational studies.

Mechanical and free living comparisons of four generations of the Actigraph activity monitor

BackgroundMore studies include multiple generations of the Actigraph activity monitor. So far no studies have compared the output including the newest generation and investigated the impact on the output of the activity monitor when enabling the low frequency extension (LFE) option. The aims were to study the responses of four generations (AM7164, GT1M, GT3X and GT3X+) of the Actigraph activity monitor in a mechanical setup and a free living environment with and without enabling the LFE option.MethodsThe monitors were oscillated in a mechanical setup using two radii in the frequency range 0.25-3.0 Hz. Following the mechanical study a convenience sample (N = 20) wore three monitors (one AM7164 and two GT3X) for 24 hours.ResultsThe AM7164 differed from the newer generations across frequencies (p < 0.05) in the mechanical setup. The AM7164 produced a higher output at the lower and at the highest intensities, whereas the output was lower at the middle intensities in the mid-range compared to the newer generations. The LFE option decreased the differences at the lower frequencies, but increased differences at the higher. In free living, the mean physical activity level (PA) of the GT3X was 18 counts per minute (CPM) (8%) lower compared to the AM7164 (p < 0.001). Time spent in sedentary intensity was 26.6 minutes (95% CI 15.6 to 35.3) higher when assessed by the GT3X compared to the AM7164 (p < 0.001). Time spend in light and vigorous PA were 23.3 minutes (95% CI 31.8 to 14.8) and 11.7 minutes (95% CI 2.8 to 0.7) lower when assessed by the GT3X compared to the AM7164 (p < 0.05). When enabling the LFE the differences in the sedentary and light PA intensity (<333 counts*10 sec-1) were attenuated (p > 0.05 for differences between generations) thus attenuated the difference in mean PA (p > 0.05) when the LFE option was enabled. However, it did not attenuate the difference in time spend in vigorous PA and it introduced a difference in time spend in moderate PA (+ 3.0 min (95% CI 0.4 to 5.6)) between the generations.ConclusionWe observed significant differences between the AM7164 and the newer Actigraph GT-generations (GT1M, GT3X and GT3X+) in a mechanical setup and in free-living. Enabling the LFE option attenuated the differences in mean PA completely, but induced a bias in the moderate PA intensities.

Youth screen-time behaviour is associated with cardiovascular risk in young adulthood: the European Youth Heart Study

Aims: We prospectively examined the association of TV viewing, computer use, and total screen time in adolescence, and change in these behaviours, with cardiovascular disease (CVD) risk factors in young adulthood. Methods and results: This was a prospective cohort study among Danish men and women (n = 435) followed for up to 12 years. Adiposity, blood pressure (BP), triglycerides, high-density lipoprotein (HDL), glucose, insulin, and self-reported TV viewing and computer use were obtained in adolescence and in young adulthood. A continuous metabolic syndrome z-score was calculated as the sum of standardized values of each risk factor (inverse of HDL). In multivariable-adjusted analyses, TV viewing and total screen time in adolescence were positively associated with adiposity, triglycerides, and metabolic syndrome z-score in young adulthood (p < 0.05). Individuals who increased their TV viewing, computer use, or total screen time with more than 2 hours/day from adolescence to young adulthood had 0.90 (95% CI 0.12 to 1.69), 0.95 (95% CI 0.01 to 1.88), and 1.40 (95% CI 0.28 to 2.51) kg/m2 higher body mass index, respectively, in young adulthood compared with individuals who remained stable or decreased their viewing time. Insulin and metabolic syndrome z-scores were also higher among individuals who increased their TV viewing, computer use, or total screen time more than 2 hours/day compared with individuals who remained stable or decreased their viewing time (p < 0.05). Conclusions: Prolonged TV viewing and total screen time during leisure time in adolescence, and increases in these behaviours, are associated with unfavourable levels of several cardiovascular risk factors in young adulthood.

Sugar-sweetened beverages consumption in relation to changes in body fatness over 6 and 12 years among 9-year-old children: the European Youth Heart Study

Background/Objectives:In parallel with the obesity epidemic, consumption of sugar-sweetened beverages (SSB) has risen over the same period. Our aim was to investigate associations between the consumption of SSB in childhood and adolescence with subsequent changes in body fatness in early adulthood.Subjects/Methods:A longitudinal study of 9-year-old children (n=283) enrolled in the Danish part of the European Youth Heart Study with a 6-year and 12-year follow-up. Data were collected at ages 9, 15 and 21 years. Multivariate regression analyses with adjustment for potential confounders were used to evaluate the effect of SSB consumption at 9 and 15 years and change in SSB consumption from 9–15 years on subsequent change in body fatness until 21 years.Results:Subjects who consumed more than one serve of SSB daily at age 15 years had larger increases in body mass index (BMI) (β=0.92, P=0.046) and waist circumference (WC) (β=2.69, P=0.04) compared to non-consumers over the subsequent 6 years. In addition, subjects who increased their SSB consumption from age 9–15 years also had larger increases in BMI (β=0.91, P=0.09) and WC (β=2.72, P=0.04) from 15–21 years, compared to those who reported no change in consumption. No significant association was observed from 9–21 years.Conclusion:This study provides new evidence that SSB consumption in adolescence and changes in SSB consumption from childhood to adolescence are both significant predictors of change in body fatness later in early adulthood.

A new approach to define and diagnose cardiometabolic disorder in children

The aim of the study was to test the performance of a new definition of metabolic syndrome (MetS), which better describes metabolic dysfunction in children. Methods. 15,794 youths aged 6–18 years participated. Mean z-score for CVD risk factors was calculated. Sensitivity analyses were performed to evaluate which parameters best described the metabolic dysfunction by analysing the score against independent variables not included in the score. Results. More youth had clustering of CVD risk factors (>6.2%) compared to the number selected by existing MetS definitions (International Diabetes Federation (IDF) < 1%). Waist circumference and BMI were interchangeable, but using insulin resistance homeostasis model assessment (HOMA) instead of fasting glucose increased the score. The continuous MetS score was increased when cardiorespiratory fitness (CRF) and leptin were included. A mean z-score of 0.40–0.85 indicated borderline and above 0.85 indicated clustering of risk factors. A noninvasive risk score based on adiposity and CRF showed sensitivity and specificity of 0.85 and an area under the curve of 0.92 against IDF definition of MetS. Conclusions. Diagnosis for MetS in youth can be improved by using continuous variables for risk factors and by including CRF and leptin.

Muscle strength in youth and cardiovascular risk in young adulthood (the European Youth Heart Study)

Background Whether muscle strength in youth is related to cardiovascular risk later in life independent of cardiorespiratory fitness is unclear. Methods We examined the independent association of isometric muscle strength in youth with cardiovascular risk factors in young adulthood using data from the Danish European Youth Heart Study; a population-based prospective cohort study among boys and girls (n=332) followed for up to 12 years. In youth maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain-gauge dynamometer and cardiorespiratory fitness was obtained from a maximal cycle ergometer test. Cardiovascular risk factors were obtained in youth and in young adulthood. Associations were examined using multivariable-adjusted regression models including major confounding factors. Results Each 1 SD difference in isometric muscle strength in youth (0.17 N/kg) was inversely associated with body mass index (BMI; −0.60 kg/m2, 95% CI −0.97 to −0.22), triglyceride (−0.09 mmol/l, 95% CI −0.16 to −0.02), diastolic blood pressure (BP) (−1.22 mm Hg, 95% CI −2.15 to −0.29) and a composite cardiovascular risk factor score (−0.61 SD, 95% CI −1.03 to −0.20) in young adulthood in multivariable-adjusted analyses including fitness. Associations to triglyceride, diastolic BP and the cardiovascular risk factor score remained with additional adjustment for waist circumference or BMI. Each 1 SD difference in isometric muscle strength in youth was significantly associated with 0.59 (95% CI 0.40 to 0.87) lower odds of general overweight/obesity in young adulthood (p=0.007) and was marginally associated with incident raised BP, raised triglyceride and low high-density lipoprotein cholesterol. Conclusions This study suggests that greater isometric muscle strength in youth is associated with lower levels of cardiovascular risk factors in young adulthood independent of fitness, adiposity and other confounding factors.

Independent and Combined Association of Muscle Strength and Cardiorespiratory Fitness in Youth With Insulin Resistance and β-Cell Function in Young Adulthood: The European Youth Heart Study

OBJECTIVE To examine the independent and combined association of isometric muscle strength of the abdomen and back and cardiorespiratory fitness (CRF) in youth with indices of glucose metabolism in young adulthood among boys and girls from the European Youth Heart Study. RESEARCH DESIGN AND METHODS We used data from a population-based prospective cohort study among youth followed up for up to 12 years (n = 317). In youth, maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain-gauge dynamometer and CRF was obtained from a maximal cycle ergometer test. Insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and β-cell function (homeostasis model assessment of β-cell function [HOMA-B]) were estimated from fasting serum insulin and glucose that were obtained in youth and at follow-up in young adulthood. RESULTS For each 1-SD difference in isometric muscle strength (0.16 N/kg) in youth, fasting insulin, HOMA-IR, and HOMA-B in young adulthood changed by −11.3% (95% CI −17.0 to −5.2), −12.2% (−18.2 to −5.7), and −8.9% (−14.4 to −3.0), respectively, in young adulthood after adjustment for CRF and personal lifestyle and demographic factors. Results for CRF were very similar in magnitude, and the magnitude of associations for both exposures was unchanged with additional adjustment for general or abdominal adiposity in youth. Combined associations of muscle strength and CRF with fasting insulin, HOMA-IR, and HOMA-B were additive, and adolescents in the highest sex-specific tertile for both isometric muscle strength and CRF had the lowest levels of these glucose metabolism outcomes. CONCLUSIONS Increasing muscle strength and CRF should be targets in youth primordial prevention strategies of insulin resistance and β-cell dysfunction.

Substituting sugar-sweetened beverages with water or milk is inversely associated with body fatness development from childhood to adolescence

OBJECTIVE The aim of this study was to examine the association between different types of beverage intake and substitution of sugar-sweetened beverages (SSBs) by water, milk, or 100% fruit juice in relation to 6-y change in body fatness. METHODS A cohort of 9-y-old children (N = 358) who participated in the Danish part of the European Youth Heart Study was followed for development of body fatness over 6 y. Multivariate linear regression was used to examine the associations between beverage intake at baseline and change in body fatness (body mass index z score [BMIz]), waist circumference (WC), and sum of four skinfolds (Σ4SF) over 6 y with adjustment for potential confounders. Substitution models were used to evaluate various beverages as alternatives to SSBs. RESULTS SSB intake at age 9 y, but not intake of other beverages, was directly associated with subsequent 6-y changes in BMIz (β = 0.05; P = 0.02) and Σ4SF (β = 0.86; P = 0.02). Daily substitution of 100 g water for 100 g SSB was inversely associated with changes in BMIz (β = -0.04; P = 0.02), WC (β =-0.29; P = 0.04), and Σ4SF (β = -0.91; P = 0.02) over 6 y. Daily substitution of 100 g milk for 100 g SSB was also inversely associated with changes in BMIz (β = -0.05; P = 0.02), WC (β = -0.33; P = 0.046), and Σ4SF (β = -0.79; P = 0.06). No effect was observed for substitution of SSB by 100% fruit juice. CONCLUSION Our results suggest that SSB intake is associated with long-term changes in body fatness in children, and replacing SSBs with water or milk, but not 100% fruit juice, is inversely associated with body fatness development.

Adiposity and Glycemic Control in Children Exposed to Perfluorinated Compounds

OBJECTIVE Our objective was to explore whether childhood exposure to perfluorinated and polyfluorinated compounds (PFCs), widely used stain- and grease-repellent chemicals, is associated with adiposity and markers of glycemic control. MATERIALS AND METHODS Body mass index, skinfold thickness, waist circumference, leptin, adiponectin, insulin, glucose, and triglyceride concentrations were assessed in 8- to 10-year-old children in 1997 in a subset of the European Youth Heart Study, Danish component. Plasma PFC concentrations were available from 499 children. Linear regression models were performed to determine the association between PFC exposure and indicators of adiposity and markers of glycemic control. RESULTS There was no association between PFC exposures and adiposity or markers of glycemic control in normal-weight children. Among overweight children, an increase of 10 ng perfluorooctane sulfonic acid/mL plasma was associated with 16.2% (95% confidence interval [CI], 5.2%-28.3%) higher insulin concentration, 12.0% (95% CI, 2.4%-22.4%) higher β-cell activity, 17.6% (95% CI, 5.8%-30.8%) higher insulin resistance, and 8.6% (95% CI, 1.2%-16.5%) higher triglyceride concentrations, and an increase of 10 ng perfluorooctanoic acid/mL plasma was associated with 71.6% (95% CI, 2.4%-187.5%) higher insulin concentration, 67.5% (95% CI, 5.5%-166.0%) higher β-cell function, 73.9% (95% CI, 0.2%-202.0%) higher insulin resistance, and 76.2% (95% CI, 22.8%-153.0%) higher triglyceride concentrations. DISCUSSION Increased PFC exposure in overweight 8- to 10-year-old children was associated with higher insulin and triglyceride concentrations. Chance findings may explain some of our results, and due to the cross-sectional design, reverse causation cannot be excluded. The findings therefore need to be confirmed in longitudinal studies.

Associations between objectively measured physical activity intensity in childhood and measures of subclinical cardiovascular disease in adolescence: prospective observations from the European Youth Heart Study

Background and aim No prospective studies have investigated the association between physical activity (PA) and carotid subclinical cardiovascular disease across childhood. Therefore, the primary aim was to investigate the association between PA intensity across childhood and carotid intima media thickness (cIMT) and stiffness in adolescence. Second, we included a clustered cardiovascular disease risk score as outcome. Methods This was a prospective study of a sample of 254 children (baseline age 8–10 years) with a 6-year follow-up. The mean exposure and the change in minutes of moderate-and-vigorous and vigorous PA intensity were measured using the Actigraph activity monitor. Subclinical cardiovascular disease was expressed as cIMT, carotid arterial stiffness and secondarily as a metabolic risk z-score including the homoeostasis model assessment score of insulin resistance, triglycerides, total cholesterol to high-density lipoprotein ratio, inverse of cardiorespiratory fitness, systolic blood pressure and the sum of four skinfolds. Results No associations were observed between PA intensity variables and cIMT or carotid arterial stiffness (p>0.05). Neither change in PA intensity (moderate-and-vigorous nor vigorous) nor mean minutes of moderate-and-vigorous PA intensity was associated to the metabolic risk z-score in adolescence (p>0.05). However, a significant inverse association was observed between mean minutes of vigorous PA and the metabolic risk z-score in adolescence independent of gender and biological maturity (standard β=–0.19 p=0.007). Conclusions A high mean exposure to, or changes in, minutes spent at higher PA intensities across childhood was not associated to cIMT or stiffness in the carotid arteries in adolescence. Our observations suggest that a high volume of vigorous PA across childhood independently associated with lower metabolic cardio vascular disease risk in adolescence.