Systematic review and meta-analysis applying PRISMA guidelines with a PICOS format was constructed to provide an overview of changes in physical performance, body composition and physical training in ...soldiers during prolonged (≥ 3 months) military operations. Twenty-four studies out of the screened 4431 records filled the inclusion criteria. A small decrease in endurance performance was the most consistent finding (Hedge's g g - 0.21, 95% CI - 0.01 to - 0.41) while small overall increases in maximal strength of the lower (g 0.33, 95% CI 0.16-0.50) and upper body (g 0.33, 95% CI 0.19-0.46) were observed. In addition, small increases in strength endurance (push-up, g 0.34, 95% CI 0.15-0.52; sit-up g 0.26, 95% CI 0.07-0.44) were observed. The overall changes in body composition were trivial. Heterogeneity in the outcome variables varied mainly between low to moderate. Large inter-individual variations were observed in physical training volume, including decrements especially in endurance training frequency and volume. A reduction in total training load was often associated with negative changes in body composition and physical performance according to the principle of training specificity. Individuals with higher initial fitness level were more susceptible to decrements in their physical performance during operation.
The aim was to study the associations of maximal strength and muscular endurance with single and clustered cardiovascular risk factors. Muscular endurance, maximal strength, cardiorespiratory fitness ...and waist circumference were measured in 686 young men (25±5 years). Cardiovascular risk factors (plasma glucose, serum high- and low-density lipoprotein cholesterol, triglycerides, blood pressure) were determined. The risk factors were transformed to z-scores and the mean of values formed clustered cardiovascular risk factor. Muscular endurance was inversely associated with triglycerides, s-LDL-cholesterol, glucose and blood pressure (β=-0.09 to - 0.23, p<0.05), and positively with s-HDL cholesterol (β=0.17, p<0.001) independent of cardiorespiratory fitness. Muscular endurance was negatively associated with the clustered cardiovascular risk factor independent of cardiorespiratory fitness (β=-0.26, p<0.05), whereas maximal strength was not associated with any of the cardiovascular risk factors or the clustered cardiovascular risk factor independent of cardiorespiratory fitness. Furthermore, cardiorespiratory fitness was inversely associated with triglycerides, s-LDL-cholesterol and the clustered cardiovascular risk factor (β=-0.14 to - 0.24, p<0.005), as well as positively with s-HDL cholesterol (β=0.11, p<0.05) independent of muscular fitness. This cross-sectional study demonstrated that in young men muscular endurance and cardiorespiratory fitness were independently associated with the clustering of cardiovascular risk factors, whereas maximal strength was not.
A simulation method to predict the reliability of clamped metal contacts under cyclic loading is presented. The main idea is to predict the development of contact condition of a joint by simulating a ...spatially variable coefficient of friction (COF) and wear. Frictional energy dissipation drives the COF evolution rule, and classic Archard's equation is employed as the evolution rule for wear depth. As both the COF and wear evolution are considered, the presented approach is capable of predicting changes in the contact condition over time. The approach is based on the Finite Element Method (FEM) and is generally applicable to industrial cases. The method is implemented as a subroutine to a FEM solver Abaqus to define a contact formulation in both normal and tangential directions. The subroutine allows full coupling between normal and tangential contact variables, which makes the approach robust also in complex industrial applications. As the effect of wear is described in the contact pressure calculation, there is no need for mesh modification. The presented approach was validated by simulating cylinder-on-plane configuration. The presented method provides similar results obtained with a simulation where geometry is updated due to wear. The results of the case study were qualitatively verified against a bolted joint type fretting experiment. The area of slip after stabilized COF distribution corresponds well with the experimental fretting scars. However, Archard's wear law seems to be limited, at least in partial slip cases, as it overestimates the amount of wear without considering entrapment of wear debris in the contact. A case study of medium speed combustion engine component is presented to show how the simulation method can be used in engine development to ensure reliable contact interfaces.
•Novel local coefficient of friction and wear simulation methodology for finite element method.•A new approach to simulate changing contact condition.•Surface damage criterion for fretting damage is introduced.•Method is applicable to real industrial size problems.
In principle, all the NMR observables, spin-spin coupling J, nuclear shielding σ and quadrupole coupling q, are magnetic field-dependent. The field dependence may be classified into two categories: ...direct and indirect (apparent) dependence. The former arises from the magnetic field-induced deformation of the molecular electronic cloud, while the latter stems from a slightly anisotropic orientation distribution of molecules, due to the interaction between the anisotropy of the molecular susceptibility tensor and the external magnetic field. Here we use 1,3,5-D3-benzene as a model system to investigate the indirect effect on the one-bond 1H-13C and 2H-13C spin-spin couplings (J couplings) and the 2H quadrupole coupling. Experiments carried out at four magnetic fields (4.7, 9.4, 14.1, and 18.8 T) show that the indirect effect is significant already at the magnetic fields commonly used in NMR spectrometers. A joint fit of the data extracted at the different field strengths provides experimental results for the susceptibility anisotropy, 2H quadrupole coupling constant and the related asymmetry parameter, as well as the one-bond CH and CD coupling constants extrapolated to vanishing field strength. The field-induced contributions are found to exceed the commonly assumed error margins of the latter. The data also indicate a primary isotope effect on the one-bond CH coupling constant. There is a tendency to further increase the magnetic field of NMR spectrometers, which leads to more pronounced indirect contributions and eventually significant direct effects as well.
The aim was to study associations of maximal strength and muscular endurance with inflammatory biomarkers independent of cardiorespiratory fitness in those with and without abdominal obesity. 686 ...young healthy men participated (25±5 years). Maximal strength was measured via isometric testing using dynamo-meters to determine maximal strength index. Muscular endurance index consisted of push-ups, sit-ups and repeated squats. An indirect cycle ergometer test until exhaustion was used to estimate maximal aerobic capacity (VO2max). Participants were stratified according to those with (>102 cm) and those without abdominal obesity (<102 cm) based on waist circumference. Inflammatory factors (C-reactive protein, interleukin-6 and tumour necrosis factor alpha) were analysed from serum samples. Maximal strength and muscular endurance were inversely associated with IL-6 in those with (β=-0.49, -0.39, respectively) (p<0.05) and in those without abdominal obesity (β=-0.08, -0.14, respectively) (p<0.05) adjusted for smoking and cardio-respiratory fitness. After adjusting for smoking and cardiorespiratory fitness, maximal strength and muscular endurance were inversely associated with CRP only in those without abdominal obesity (β=-0.11, -0.26, respectively) (p<0.05). This cross-sectional study demonstrated that muscular fitness is inversely associated with C-reactive protein and IL-6 concentrations in young adult men independent of cardiorespi-ratory fitness.
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•Field-induced deuterium quadrupolar splittings at 1GHz.•13C satellites.•Natural abundance deuterium.•Sign determination of quadrupolar splittings.
The deuterium NMR spectrum of ...benzene-d6 in a high field spectrometer (1GHz protons) exhibits a magnetic field-induced deuterium quadrupolar splitting Δν. The magnitude of Δν observed for the central resonance is smaller than that observed for the 13C satellite doublets Δν′. This difference, Δ(Δν)=Δν′−Δν, is due to unresolved fine structure contributions to the respective resonances. We determine the origins of and simulate this difference, and report pulse sequences that exploit the connectivity of the peaks in the 13C and 2H spectra to determine the relative signs of the indirect coupling, JCD, and Δν. The positive sign found for Δν is consonant with the magnetic field biasing of an isolated benzene molecule—the magnetic energy of the aromatic ring is lowest for configurations where the C6 axis is normal to the field. In the neat liquid the magnitude of Δν is decreased by the pair correlations in this prototypical molecular liquid.
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