Circulating myostatin is reduced with aging in humans but not altered by short-term, high intensity training

Introduction: Ageing involves a loss of muscle mass and function. The rate of decline is associated with negative health outcomes and increased mortality (1). Muscle atrophy is observed at a predictable rate from 30 years of age (2), however maintenance of function is seen in masters athletes > 60 years of age (3). Myostatin acts as a negative regulator of muscle mass (4) and underlies hypertrophy with chronic resistance training (5) and atrophy in chronic conditions (4). Experiment 1: Declared healthy participants (n = 83, 18 - 75 years of age, 36 male, 47 female) were recruited. Body composition, metabolic rate, grip strength and 6-minute walk test were recorded. Venous blood was collected and total myostatin concentration (herein referred to as myostatin) quantified by enzyme-linked immunosorbent assay. Total myostatin was lower in females compared with males (2176.1 [135.3] vs. 2788.7 [180.2] pg.mL-1 [p = 0.007]). Stepwise regression observed that myostatin concentration is best predicted firstly by gender, then by age (r = 0.399, p = 0.02), and was not further improved by the addition of measures of metabolism, muscle mass or function. Experimental 2: A cohort of aged sedentary (SED) males (n = 14; 63.9 [5.6] years of age) and masters athletes (lifelong exerciser [LEX]; n = 10, 61.1 [5.8] years of age) completed 6 weeks of high intensity interview training (HITT). Two way ANOVA suggested no group (SED, LEX) × time (pre, post) interaction on myostatin concentration (p = 0.649), nor a main effect of time (p = 0.757), however there was a trend towards increased myostatin in the LEX group relative to SED (p = 0.083). Discussion: Loss of muscle mass and function occurs at a predictable rate from ~30 years of age, however the rate of loss differs between active and inactive populations. Here we demonstrate that total circulating myostatin decreases as age increases, and differs significantly between males and females. Total circulating myostatin negatively correlates with increasing age, however alterations in myostatin do not appear after short term training interventions. Longer term activity may alter myostatin, thus our next work will follow up experiment 2 with a 3 year longitudinal analysis

Circulating myostatin is reduced with aging in humans but not altered by short-term, high intensity training

Ageing involves a loss of muscle mass and function. The rate of decline is associated with negative health outcomes and increased mortality (1). Muscle atrophy is observed at a predictable rate from 30 years of age (2), however maintenance of function is seen in masters athletes > 60 years of age (3). Myostatin acts as a negative regulator of muscle mass (4) and underlies hypertrophy with chronic resistance training (5) and atrophy in chronic conditions (4). Experiment 1: Declared healthy participants (n = 83, 18 - 75 years of age, 36 male, 47 female) were recruited. Body composition, metabolic rate, grip strength and 6-minute walk test were recorded. Venous blood was collected and total myostatin concentration (herein referred to as myostatin) quantified by enzyme-linked immunosorbent assay. Total myostatin was lower in females compared with males (2176.1 [135.3] vs. 2788.7 [180.2] pg.mL-1 [p = 0.007]). Stepwise regression observed that myostatin concentration is best predicted firstly by gender, then by age (r = 0.399, p = 0.02), and was not further improved by the addition of measures of metabolism, muscle mass or function. Experimental 2: A cohort of aged sedentary (SED) males (n = 14; 63.9 [5.6] years of age) and masters athletes (lifelong exerciser [LEX]; n = 10, 61.1 [5.8] years of age) completed 6 weeks of high intensity interview training (HITT). Two way ANOVA suggested no group (SED, LEX) × time (pre, post) interaction on myostatin concentration (p = 0.649), nor a main effect of time (p = 0.757), however there was a trend towards increased myostatin in the LEX group relative to SED (p = 0.083). Discussion: Loss of muscle mass and function occurs at a predictable rate from ~30 years of age, however the rate of loss differs between active and inactive populations. Here we demonstrate that total circulating myostatin decreases as age increases, and differs significantly between males and females. Total circulating myostatin negatively correlates with increasing age, however alterations in myostatin do not appear after short term training interventions. Longer term activity may alter myostatin, thus our next work will follow up experiment 2 with a 3 year longitudinal analysis

Modeling And Simulating A Breeder Hybrid Soliton Reactor

International audienceUnderstanding and controlling early damage initiation and evolution are amongst the most important issues in nuclear power plants. Integranular cracking has been known to occur in both austenitic steels and nickel based alloys. Modelling efforts are under way to understand this phenomenon on the grain-level scale where the influence of the microstructure plays an important role. Here, the initiation and evolution of integranular cracking can be modelled using the advanced finite element approaches with explicit account of the grains, their crystallographic orientation and explicit inclusion of grain boundaries. The cohesive-zone approach, with damage initiation and evolution, can be used for grain boundaries. However, the stability of such an approach can be problematic, especially in cases where there are a number of inter-granular cracks. These cracks can form complex networks which can have a negative impact on the stability of the analysis. This work addresses some of the issues related to the stability. The influence of the finite element individual model parameters like convergence controls and numerical viscosity on the model convergence is looked at. The effects are demonstrated on a simple geometry containing 3 grains. It is shown that the numerical viscosity has the highest beneficial influence on the convergence. However values of numerical viscosity of more than 10 % of the time step should be avoided

Investigating the breeding capabilities of hybrid soliton reactors

International audienc

Identifying potential types of guidance for supporting student inquiry when using virtual and remote labs in science: a literature review

The aim of this review is to identify specific types of guidance for supporting student use of online labs, that is, virtual and remote labs, in an inquiry context. To do so, we reviewed the literature on providing guidance within computer supported inquiry learning (CoSIL) environments in science education and classified all identified guidance according to a recent taxonomy of types of guidance. In addition, we classified the types of guidance in phases of inquiry. Moreover, we examined whether the types of guidance identified for each inquiry phase were found to be effective in promoting student learning, as documented in the CoSIL research. This review identifies what types of effective guidance currently exist and can be applied in developing future CoSIL environments, especially CoSIL environments with online labs. It also highlights the needs/shortcomings of these available types of guidance. Such information is crucial for the design and development of future CoSIL environments with online lab

Analysing the relationship between the problem-solving-related beliefs, competence and teaching of three Cypriot primary teachers

In this article, we analyse the problem-solving-related beliefs, competence and classroom practice of three Cypriot upper-primary teachers. Data derived from semistructured interviews focused on teachers’ beliefs about the nature of mathematical problems, problem-solving, and their competence as both problem-solvers and teachers of problem-solving; clinical interviews during which teachers solved a context-free geometrical problem, and observations of a lesson during which teachers introduced that problem to students of grade six. Analyses, structured by a framework derived from key problem-solving literature, indicated firstly, that the framework was an effective tool, sensitive to variation within and across the data from teachers, and secondly, that all participants, in largely explicable ways, exhibited consistency and inconsistency in the ways in which their beliefs, competence and practice interacted. Some implications for further research are discussed