Insights into physical activity and cardiovascular disease risk in young children: IDEFICS study

Abstract The association between physical activity and cardiovascular disease risk factors in children has been the focus of research for over two decades. The majority of this research has focused on children over 10 years of age with little information on very young children. The data recently published in BMC Medicine by Jiménez-Pavón and colleagues suggest that adverse cardiovascular disease (CVD) risk profiles, as indicated by a clustered risk score for the metabolic syndrome, are evident in very young children (two to six years of age), but differ between the sexes. The authors evaluated the relationship of CVD risk profiles and protective levels of moderate-to-vigorous physical activity (MVPA) and concluded that boys aged six years or younger needed >60 minutes of MVPA per day, whereas boys from six to nine years of age needed >80 minutes of MVPA per day; girls in either age group needed approximately 15 minutes less. Therefore, when clinicians recommend physical activity for children they should evaluate “at risk” children on a case-by-case basis rather than using generalized guidelines.Please see related research: http://www.biomedcentral.com/1741-7015/11/172

Exercise-Induced Glycogen Reduction Increases Muscle Activity

International Journal of Exercise Science 9(3): 336-346, 2016. Intramuscular glycogen stores are an important energy source during extended bouts of strenuous exercise. A substantial reduction in glycogen could influence neural muscular drive and result in a decreasing quality of exercise performance and potentially increased injury rates. The aim of this study was to examine the effect of glycogen reduction on motor drive as determined by the surface electromyogram (EMG) amplitude and median frequency during a cycling graded exercise test. Eight trained cyclists performed a discontinuous cycling graded exercise test to exhaustion under both normal and glycogen reduced conditions. EMG was collected from the vastus lateralis. Repeated measures regression models indicated that EMG amplitudes were elevated at cycling workloads higher than 196 Watts and metabolic workloads higher than 40.8 ml/kg/min, corresponding to 77% VO2max. There was no effect of increases in workload or glycogen reduction on EMG median frequency. Changes in mechanical and metabolic workload had a substantial effect on EMG amplitude (Cohen’s f2 = 0.227 and 0.247, respectively), but not median frequency (Cohen’s f2 = 0.026 and 0.033, respectively). Thus, EMG amplitude is a more effective and reliable measure to examine changes in motor drive during variable workload conditions and metabolic perturbations. The results suggest that healthy glycogen reduced humans require higher levels of muscle activity in order to attain a given mechanical and metabolic workload. This may affect the long term performance of professional and military athletes who need to be able to perform at a high level for extended periods of activity

Actical Accelerometry Cut-points for Quantifying Levels of Exertion: Comparing Normal and Overweight Adults

Int J Exerc Sci 5(2) : 170-182, 2012. Weight, body fatness and ambulatory pattern all have the potential to affect accelerometer output and cause differences in output between overweight and normal-weight adults. The purpose of this study was to determine if Actical (Philips Respironics, Bend, OR) activity count cut-points for moderate and vigorous intensity exercise are different for overweight adults compared to normal-weight adults. Overweight adults with BMI \u3e25 kg/m² (n=29) and Normal-Weight adults (n=25) walked at 3.2 and 4.8 km∙h-1 and ran at 6.4 km∙h-1 on a treadmill while simultaneously wearing an Actical accelerometer and obtaining measurements of oxygen uptake. Counts per minute (counts∙min-1) were determined at 3 METS (moderate) and 6 METS (vigorous) using ROC curves. The counts∙min-1 at 3 METs was 1726 and 1923 counts∙min-1 for Overweight and Normal-Weight groups, respectively. The cut-points at 6 METs were 4117 and 4032 counts∙min-1 for Overweight and Normal-Weight groups, respectively. The differences between groups were not statistically significant (p\u3e0.73 for both). Correlations between BMI and counts∙min-1 were not significant (p\u3e0.05) at any speed for the Normal-Weight group but were significant at 3.2 and 4.8 km∙h-1 for the Overweight group. Although there appears to be some relationship between activity counts∙min-1 and BMI, the results suggest that similar cut-points may be used for normal weight and overweight adults. However, the greater variability in counts at each speed and lower ROC curve areas for overweight adults suggest that it is harder to classify the activity intensity of overweight subjects compared to normal weight subjects

Multi-Line Gamma-Ray Spectrometer Performance of a Si(Li) Detector Stack

Experimental data is presented which for the first time displays multi-line spectrometer performance of a Si(Li) detector stack at elevated temperature. The stack consists of four elements, each with a 2 cm diameter active area. Ba-133 and Ag-110m spectra are obtained using various techniques to enhance the peak-to-background ratio. Spectral data are shown as a function of temperature (94 K less than or = T less than or = 230 K) using optimized peak shaping

Interrelationships Among Changes in Leptin, Insulin, Cortisol and Growth Hormone and Weight Status in Youth

Objective: While acute alterations in leptin, insulin, cortisol and growth hormone (GH) levels have been reported in children following weight change interventions, little is known about natural hormonal changes as children grow and how these changes are affected b

Determinants of adolescent physical activity and inactivity patterns.

Objectives. Despite recognition of the important influence of environmental determinants on physical activity patterns, minimal empirical research has been done to assess the impact of environmental/contextual determinants of physical activity. This article aims to investigate environmental and sociodemographic determinants of physical activity and inactivity patterns among subpopulations of US adolescents. We define environmental determinants as modifiable factors in the physical environment that impose a direct influence on the opportunity to engage in physical activity. The present research examines environmental and sociodemographic determinants of physical activity and inactivity with the implication that these findings can point toward societal-level intervention strategies for increasing physical activity and decreasing inactivity among adolescents

The Relationship between Changes in Weight Status and Insulin Resistance in Youth

This study examined changes in insulin resistance (IR) in 120 youth over two years. IR was quantified via homeostatic model (HOMA-IR), and weight status changes were quantified via body mass index (BMI). When all participants were considered, the mean HOMA-IR and BMI increased 13.4% and 1.65 units, respectively. Change in BMI z-score and percent change in HOMA-IR were moderately associated (r = 0.39). Follow-up analyses were performed for the following weight groups: NN (normal at baseline and two years later), NO (normal to overweight), ON (overweight to normal), and OO (overweight at both points). The NO group had a greater change in HOMA-IR (+50%) compared to other groups: ON (−8%), NN (+2%), and OO (−0.1%) (P < .05). The association between changes in BMI z-score and HOMA-IR was r = 0.49 when only the NO and ON groups were included. These results reinforce the importance of preventing youth from becoming overweight to control IR

Pyroelectric detectors

The multi-agency, long-term Global Change programs, and specifically NASA's Earth Observing system, will require some new and advanced photon detector technology which must be specifically tailored for long-term stability, broad spectral range, cooling constraints, and other parameters. Whereas MCT and GaAs alloy based photovoltaic detectors and detector arrays reach most impressive results to wavelengths as long as 12 microns when cooled to below 70 K, other materials, such as ferroelectrics and pyroelectrics, appear to offer special opportunities beyond 12 microns and above 70 K. These materials have found very broad use in a wide variety of room temperature applications. Little is known about these classes of materials at sub-room temperatures and no photon detector results have been reported. From the limited information available, researchers conclude that the room temperature values of D asterisk greater than or equal to 10(exp 9) cm Hz(exp 1/2)/W may be improved by one to two orders of magnitude upon cooling to temperatures around 70 K. Improvements of up to one order of magnitude appear feasible for temperatures achievable by passive cooling. The flat detector response over a wavelength range reaching from the visible to beyond 50 microns, which is an intrinsic advantage of bolometric devices, makes for easy calibration. The fact that these materials have been developed for reduced temperature applications makes ferro- and pyroelectric materials most attractive candidates for serious exploration

Sex Differences in the Association between Level of Childhood Interleukin-6 and Insulin Resistance in Adolescence

The purpose of this study was to determine whether levels of interleukin-6 (IL-6) in childhood are related to insulin resistance in adolescence. Further, to explore how fatness and cardiorespiratory fitness (VO2peak) moderate this relationship. Methods. 292 nine-year-old children (n = 292) were followed for 4 years. Anthropometrics and VO2peak were measured. Fasting blood samples were analyzed for IL-6, insulin, and glucose. Homeostasis model assessment (HOMA-IR) was used as a measure of insulin resistance. Results. For girls but not boys, levels of IL-6 at age 9 yrs correlated with HOMA-IR at age 13 yrs: r = 0.223, P = 0.008. Girls with IL-6 levels within the highest quartile at age 9 yrs had an odds ratio of 3.68 (CI = 1.58–8.57) being in the highest quartile of HOMA-IR four years later. Conclusion. In this cohort, IL-6 levels in childhood were related to insulin resistance in adolescence, but only for girls