Exercise detraining: Applicability to microgravity

Physical training exposes the various systems of the body to potent physiologic stimuli. These stimuli induce specific adaptations that enhance an individual's tolerance for the type of exercise encountered in training. The level of adaptation and the magnitude of improvement in exercise tolerance is proportional to the potency of the physical training stimuli. Likewise, our bodies are stimulated by gravity, which promotes adaptations of both the cardiovascular and skeletal muscles. Exposure to microgravity removes normal stimuli to these systems, and the body adapts to these reduced demands. In many respects the cessation of physical training in athletes and the transition from normal gravity to microgravity represent similar paradigms. Inherent to these situations is the concept of the reversibility of the adaptations induced by training or by exposure to normal gravity. The reversibility concept holds that when physical training is stopped (i.e., detraining) or reduced, or a person goes from normal gravity to microgravity, the bodily systems readjust in accordance with the diminished physiologic stimuli. The focus of this chapter is on the time course of loss of the adaptations to endurance training as well as on the possibility that certain adaptations persist, to some extent, when training is stopped. Because endurance exercise training generally improves cardiovascular function and promotes metabolic adaptations within the exercising skeletal musculature, the reversibility of these specific adaptations is considered. These observations have some applicability to the transition from normal to microgravity

Efectes fisiològics de la deshidratació. Per què els esportistes han d'ingerir líquids durant l'exercici en la calor?

Durant l'exercici prolongat fet en condicions de calor ambien-tal, els esportistes incorren en nivells de deshidratació bastant acusats degut principalment a les grans pèrdues d'aigua a través de la suor (1-2 l/h). Dades recents demostren que aquesta deshidratació progressiva causa alteracions significatives dels sistemes cardiovascular, metabòlic, termoregulador i endocrí, que a la vegada poden anticipar l'aparició de la fatiga, ocasionar un cop de calor o, fins i tot, causar la mort. Més concretament, la hipertèrmia, l'augment de la freqüència cardíaca i la disminució del cabal cardíac durant l'exercici prolongat en la calor es correlacionen directament amb la magnitud de la deshidratació. Aquests efectes negatius de la deshidratació es manifesten independentment de la modalitat i de la intensitat de l'exercici. Amb la ingestió d'un volum de líquid equivalent a les pèrdues d'aigua per la sudoració es prevé la deshidratació per tant, s'eviten aquestes alteracions funcionals. Així doncs, des d'un punt de vista estrictament fisiològic, no hi ha cap dubte que l'esquema més idoni de reposició hídrica durant l'exercici en la calor és aquell en el qual es reponen completament les pèrdues d'aigua provocades per la sudoració. Tanmateix, des d'un punt de vista competitiu, els atletes han de trobar el seu règim òptim de reposició hídrica. Els beneficis fisiològics d'una reposició hídrica completa possibiliten una major velocitat de carrera durant l'última part de la competició. Tanmateix, la ingesta de grans volums de fluids pot obligar a reduir la velocitat de carrera i provocar trastorns gas-trointestinals. Per assegurar el màxim benefici de la ingestió de grans volums de líquids durant l'exercici evitant els seus desavantatges, els esportistes han de beure durant els seus entrenaments

Efectos fisiológicos de la deshidratación. ¿Por qué los deportistas deben ingerir líquidos durante el ejercicio en el calor?

Durante el ejercicio prolongado realizado en condiciones de calor ambiental, los deportistas incurren en niveles de deshidratación bastante acusados debido principalmente a las grandes pérdidas de agua a través del sudor (1-2 l/h). Datos recientes demuestran que esta deshidratación progresiva causa alteraciones significativas de los sistemas cardiovascular, metabólico, termorregulador y endocrino, que a su vez pueden anticipar la aparición de la fatiga, ocasionar un golpe de calor o incluso causar la muerte. Más concretamente, la hipertermia, el aumento de la frecuencia cardíaca y la disminución del gasto cardíaco durante el ejercicio prolongado en el calor se correlacionan directamente con la magnitud de la deshidratación. Estos efectos negativos de la deshidratación se manifiestan independientemente de la modalidad y de la intensidad del ejercicio. Con la ingestión de un volumen de líquido equivalente a las pérdidas de agua por la sudoración se previene la deshidratación y, por lo tanto, se evitan estas alteraciones funcionales. Así pues, desde un punto de vista estrictamente fisiológico, no cabe ninguna duda que el esquema mas idóneo de reposición hídrica durante el ejercicio en el calor es aquel en el que se reponen completamente las pérdidas de agua provocadas por la sudoración. Sin embargo, desde un punto de vista competitivo, los atletas deben encontrar su régimen óptimo de reposición hídrica. Los beneficios fisiológicos de una reposición hídrica completa posibilitan una mayor velocidad de carrera durante la última parte de la competición. Sin embargo, la ingesta de grandes volúmenes de fluidos puede obligar a reducir la velocidad de carrera y provocar trastornos gastrointestinales. Para asegurar el máximo beneficio de la ingestión de grandes volúmenes de líquidos durante el ejercicio evitando sus desventajas, los deportistas deben beber durante sus entrenamientos

Effects of short sprint interval training on aerobic and anaerobic indices: A systematic review and meta-analysis

The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O2max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, and SPORTDiscus were systematically searched on May 9, 2020, and updated on September 14, 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of “all-out” and non-“all-out” efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies were deemed eligible. The estimated SMDs based on the random-effects model were −0.56 (95% CI: −0.79, −0.33, p  0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g., cycling, running, paddling, and punching) to improve V̇O2max, aerobic, and anaerobic performances in physically active young healthy adults and athletes

Relationships Between Lower Body Muscular Strength and Power After Downhill Running

The purpose of this investigation was to assess relationships between maximal isometric lower body strength and three different measurements of maximal lower body neuromuscular power after a bout of eccentric lower body exercise. Forty-eight recreationally active males performed 20 minutes of downhill running (7.5 mph, -10% grade). Isometric knee extensor strength (KE), maximal cycling power (PMAX), vertical jump height (VJ), and 10-meter sprint time (10m) were assessed immediately prior to exercise (baseline) and repeated 2, 24, 48, 72, and 96 h after exercise. Data are reported as mean±SEM. There was a significant effect of time on all measurements throughout the 96 h period after exercise. Isometric KE strength was 129.0±3.3, 113.2±3.3, 115.8±3.3, 119.0±3.2 118.1±3.3 and 119.7±3.4 kg at baseline, 2, 24, 48, 72, and 96 h post-exercise, respectively. PMAX was 1086±31, 1014±28, 1024±32, 1042±31, 1042±30, and 1044±31 watts at baseline, 2, 24, 48, 72, and 96-hours post-exercise, respectively. VJ was 50.2±1.2, 48.7±1.2, 49.1±1.3, 49.7±1.3, 50.6±1.3, and 50.5±1.3 cm at baseline, 2, 24, 48, 72, and 96-hours post-exercise, respectively. 10m sprint time was 1.76±0.02, 1.80±0.03, 1.80±0.02, 1.79±0.02, 1.77±0.02, and 1.77±0.02 sec at baseline, 2, 24, 48, 72, and 96-hours post-exercise, respectively. There were significant relationships between isometric KE strength and both PMAX (R2=0.31, p\u3c0.05) and VJ height (R2=0.11, p\u3c0.05). Additionally, there was a significant relationship between isometric KE strength and Pmax at each time point (R2=0.23-0.34, p\u3c0.05). This was not true for VJ height or 10m sprint time. No relationship was present between isometric KE strength and 10m sprint time (R2=0.01). The primary finding of this study was a significant relationship between isometric KE strength and PMAX and that this relationship was maintained at each time point after eccentric exercise. Therefore, we conclude that PMAX is a reliable method to assess decrements in neuromuscular power and athletic performance after a bout of muscle damaging eccentric exercise

Architecture and performance of the KM3NeT front-end firmware

The KM3NeT infrastructure consists of two deep-sea neutrino telescopes being deployed in the Mediterranean Sea. The telescopes will detect extraterrestrial and atmospheric neutrinos by means of the incident photons induced by the passage of relativistic charged particles through the seawater as a consequence of a neutrino interaction. The telescopes are configured in a three-dimensional grid of digital optical modules, each hosting 31 photomultipliers. The photomultiplier signals produced by the incident Cherenkov photons are converted into digital information consisting of the integrated pulse duration and the time at which it surpasses a chosen threshold. The digitization is done by means of time to digital converters (TDCs) embedded in the field programmable gate array of the central logic board. Subsequently, a state machine formats the acquired data for its transmission to shore. We present the architecture and performance of the front-end firmware consisting of the TDCs and the state machine

Gene Expression Changes in the Prefrontal Cortex, Anterior Cingulate Cortex and Nucleus Accumbens of Mood Disorders Subjects That Committed Suicide

Suicidal behaviors are frequent in mood disorders patients but only a subset of them ever complete suicide. Understanding predisposing factors for suicidal behaviors in high risk populations is of major importance for the prevention and treatment of suicidal behaviors. The objective of this project was to investigate gene expression changes associated with suicide in brains of mood disorder patients by microarrays (Affymetrix HG-U133 Plus2.0) in the dorsolateral prefrontal cortex (DLPFC: 6 Non-suicides, 15 suicides), the anterior cingulate cortex (ACC: 6NS, 9S) and the nucleus accumbens (NAcc: 8NS, 13S). ANCOVA was used to control for age, gender, pH and RNA degradation, with P≤0.01 and fold change±1.25 as criteria for significance. Pathway analysis revealed serotonergic signaling alterations in the DLPFC and glucocorticoid signaling alterations in the ACC and NAcc. The gene with the lowest p-value in the DLPFC was the 5-HT2A gene, previously associated both with suicide and mood disorders. In the ACC 6 metallothionein genes were down-regulated in suicide (MT1E, MT1F, MT1G, MT1H, MT1X, MT2A) and three were down-regulated in the NAcc (MT1F, MT1G, MT1H). Differential expression of selected genes was confirmed by qPCR, we confirmed the 5-HT2A alterations and the global down-regulation of members of the metallothionein subfamilies MT 1 and 2 in suicide completers. MTs 1 and 2 are neuro-protective following stress and glucocorticoid stimulations, suggesting that in suicide victims neuroprotective response to stress and cortisol may be diminished. Our results thus suggest that suicide-specific expression changes in mood disorders involve both glucocorticoids regulated metallothioneins and serotonergic signaling in different regions of the brain

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead