Effects of Strength Training on Postpubertal Adolescent Distance Runners

**Purpose** Strength training activities have consistently been shown to improve running economy (RE) and neuromuscular characteristics, such as force producing ability and maximal speed, in adult distance runners. However the effects on adolescent (<18 years) runners remains elusive. This randomized control trial aimed to examine the effect of strength training on several important physiological and neuromuscular qualities associated with distance running performance. **Methods** Participants (n=25, 13 female, 17.2 ±1.2 years) were paired according to their sex and RE and randomly assigned to a ten week strength training group (STG), or a control group (CG) who continued their regular training. The STG performed twice weekly sessions of plyometric, sprint and resistance training in addition to their normal running. Outcome measures included body mass, maximal oxygen uptake (V˙O2max), speed at V˙O2max, running economy (quantified as energy cost), speed at fixed blood lactate concentrations (sFBLC), 20 m sprint, and maximum voluntary contraction (MVC) during an isometric quarter-squat. **Results** Eighteen participants (STG, n=9, 16.1 ±1.1 years; CG, n=9, 17.6 ±1.2 years) completed the study. The STG displayed small improvements (3.2-3.7%, ES: 0.31-0.51) in running economy that were inferred as ‘possibly beneficial’ for an average of three submaximal speeds. Trivial or small changes were observed for body composition variables, V˙O2max and sV˙O2max, however the training period provided likely benefits to sFBLC in both groups. Strength training elicited a very likely benefit and a possible benefit to sprint time (ES: 0.32) and MVC (ES: 0.86) respectively. **Conclusion** Ten weeks of strength training added to the programme of a post-pubertal distance runner was highly likely to improve maximal speed, and enhances running economy by a small extent, without deleterious effects on body composition or other aerobic parameters

Status and Trends of Physical Activity Surveillance, Policy, and Research in 164 Countries: Findings From the Global Observatory for Physical Activity—GoPA! 2015 and 2020 Surveys

Background: Physical activity (PA) surveillance, policy, and research efforts need to be periodically appraised to gain insight into national and global capacities for PA promotion. The aim of this paper was to assess the status and trends in PA surveillance, policy, and research in 164 countries. Methods: We used data from the Global Observatory for Physical Activity (GoPA!) 2015 and 2020 surveys. Comprehensive searches were performed for each country to determine the level of development of their PA surveillance, policy, and research, and the findings were verified by the GoPA! Country Contacts. Trends were analyzed based on the data available for both survey years. Results: The global 5-year progress in all 3 indicators was modest, with most countries either improving or staying at the same level. PA surveillance, policy, and research improved or remained at a high level in 48.1%, 40.6%, and 42.1% of the countries, respectively. PA surveillance, policy, and research scores decreased or remained at a low level in 8.3%, 15.8%, and 28.6% of the countries, respectively. The highest capacity for PA promotion was found in Europe, the lowest in Africa and low- and lower-middle-income countries. Although a large percentage of the world’s population benefit from at least some PA policy, surveillance, and research efforts in their countries, 49.6 million people are without PA surveillance, 629.4 million people are without PA policy, and 108.7 million live in countries without any PA research output. A total of 6.3 billion people or 88.2% of the world’s population live in countries where PA promotion capacity should be significantly improved. Conclusion: Despite PA is essential for health, there are large inequalities between countries and world regions in their capacity to promote PA. Coordinated efforts are needed to reduce the inequalities and improve the global capacity for PA promotion

A scientific approach to quantifying the efficiency and efficacy of dust curtains on a Sandvik mb650 continuous miner at kestrel colliery whilst mining a full face of roof stone during an overcast construction

With the correct identification and continued increase in CWP and related occupational lung disease in the Australian coal mining industry since May 2015, the industry’s focus has been directed at mining operations achieving statutory respirable dust level compliance to AS2985. The majority of dust control techniques currently installed and operational in Australian coal mines have been developed in the USA, UK and other western countries and their application is more suited to low to medium coal seam heights up to 3m. The Australian mining experience has indicated that the efficiency of some of the existing respirable dust control methods reduce significantly in thick coal seams, under high production environments and when mining roof stone. As the current trend in the industry is to substantially increase production levels, there is an urgent need for detailed investigation of various dust control options and development of appropriate dust management strategies based on quantifying the efficiency and efficacy of installed controls to mitigate respirable dust from the working environment. This paper details the approach taken to quantify the efficiency and efficacy of installed face curtains for respirable dust mitigation on a Sandvik MB650 continuous miner whilst mining a full face of roof stone cutting an overcast in the mains at Kestrel Colliery. Results of the project have shown that the installed face curtains are not suitable as a dust mitigation control

A scientific approach to quantifying the efficiency and efficacy of dust curtains on a Sandvik mb650 continuous miner at kestrel colliery whilst mining a full face of roof stone during an overcast construction

With the correct identification and continued increase in CWP and related occupational lung disease in the Australian coal mining industry since May 2015, the industry’s focus has been directed at mining operations achieving statutory respirable dust level compliance to AS2985. The majority of dust control techniques currently installed and operational in Australian coal mines have been developed in the USA, UK and other western countries and their application is more suited to low to medium coal seam heights up to 3m. The Australian mining experience has indicated that the efficiency of some of the existing respirable dust control methods reduce significantly in thick coal seams, under high production environments and when mining roof stone. As the current trend in the industry is to substantially increase production levels, there is an urgent need for detailed investigation of various dust control options and development of appropriate dust management strategies based on quantifying the efficiency and efficacy of installed controls to mitigate respirable dust from the working environment. This paper details the approach taken to quantify the efficiency and efficacy of installed face curtains for respirable dust mitigation on a Sandvik MB650 continuous miner whilst mining a full face of roof stone cutting an overcast in the mains at Kestrel Colliery. Results of the project have shown that the installed face curtains are not suitable as a dust mitigation control

Earth\u27s magnetosphere and outer radiation belt under sub-Alfvénic solar wind

The interaction between Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values \u3c1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets

The Storm Time Development of Source Electrons and Chorus Wave Activity During CME- and CIR-Driven Storms

Whistler mode chorus waves influence the dynamics of the Earth\u27s radiation belts and the inner magnetosphere through gyroresonant wave particle interactions. Chorus waves are generated by anisotropic hot electrons from a few to tens of keV, called source electrons, which have increased access from the nightside plasma sheet to the inner magnetosphere during geomagnetic storms. The primary drivers of geomagnetic storms are coronal mass ejections (CMEs) and corotating interaction regions (CIRs). Through differences in their characteristic physical parameters, they can each impact the nightside plasma sheet differently. Using Van Allen Probes observations, we have conducted a superposed epoch analysis of chorus wave activity and source electron development across all local times between L = 2–6 during 25 CME- and 35 CIR-driven storms. The superposed epoch analysis shows that chorus wave power follows the storm phase-dependent access of the source electron population. Chorus waves and source electrons are observed on the dawnside during the main phase, when open drift path access via eastward convective drift from the plasma sheet is enhanced. During the recovery phase, chorus waves and source electrons are observed at all magnetic local times with low intensities, exemplifying the formation of a weak symmetric, trapped electron population. A linear theory approximation for wave growth from source electron observations shows that increased wave growth follows the enhanced source electrons during each storm phase. CME and CIR storms display similar behavior and levels of average wave power; however, chorus wave activity reaches lower L-shells during CME storms on average

The Storm-Time Ring Current Response to ICMEs and CIRs Using Van Allen Probe Observations

Using Van Allen Probe observations of the inner magnetosphere during geomagnetic storms driven by interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs), we characterize the impact of these drivers on the storm-time ring current development. Using 25 ICME- and 35 CIR-driven storms, we have determined the ring current pressure development during the prestorm, main, early-recovery, and late-recovery storm phases, as a function of magnetic local time, L shell and ion species (H+, He+, and O+) over the 100- to 600-keV energy range. Consistent with previous results, we find that during the storm main phase, most of the ring current pressure in the inner magnetosphere is contributed by particles on open drift paths drifting duskward leading to a strong partial ring current. The largest difference between the ICME and CIR ring current responses during the storm main and early-recovery phases is the difference in the response of the \u3c~55-keV O+ to these drivers. While the H+ pressure response shows similar source and convection patterns for ICME and CIR storms, the O+ pressure response is significantly stronger for ICME storms. The ICME O+ pressure increases more strongly than H+ with decreasing L and peaks at lower L shells than H+

The Outer Radiation Belt Response to the Storm Time Development of Seed Electrons and Chorus Wave Activity During CME and CIR Driven Storms

Gyroresonant wave-particle interactions with very low frequency whistler mode chorus waves can accelerate subrelativistic seed electrons (hundreds of keV) to relativistic energies in the outer radiation belt during geomagnetic storms. In this study, we conduct a superposed epoch analysis of the chorus wave activity, the seed electron development, and the outer radiation belt electron response between L* = 2.5 and 5.5, for 25 coronal mass ejection and 35 corotating interaction region storms using Van Allen Probes observations. Electron data from the Magnetic Electron Ion Spectrometer and Relativistic Electron Proton Telescope instruments are used to monitor the storm-phase development of the seed and relativistic electrons, and magnetic field measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science instrument are used to identify the chorus wave activity. Our results show a deeper (lower L*), stronger (higher flux), and earlier (epoch time) average seed electron enhancement and a resulting greater average radiation belt electron enhancement in coronal mass ejection storms compared to the corotating interaction region storms despite similar levels and lifetimes of average chorus wave activity for the two storm drivers. The earlier and deeper seed electron enhancement during the coronal mass ejection storms, likely driven by greater convection and substorm activity, provides a higher probability for local acceleration. These results emphasize the importance of the timing and the level of the seed electron enhancements in radiation belt dynamics

Mapping Development of the Human Intestinal Niche at Single-Cell Resolution

The human intestinal stem cell niche supports self-renewal and epithelial function, but little is known about its development. We used single-cell mRNA sequencing with in situ validation approaches to interrogate human intestinal development from 7–21 weeks post conception, assigning molecular identities and spatial locations to cells and factors that comprise the niche. Smooth muscle cells of the muscularis mucosa, in close proximity to proliferative crypts, are a source of WNT and RSPONDIN ligands, whereas EGF is expressed far from crypts in the villus epithelium. Instead, an PDGFRAHI/F3HI/DLL1HI mesenchymal population lines the crypt-villus axis and is the source of the epidermal growth factor (EGF) family member NEUREGULIN1 (NRG1). In developing intestine enteroid cultures, NRG1, but not EGF, permitted increased cellular diversity via differentiation of secretory lineages. This work highlights the complexities of intestinal EGF/ERBB signaling and delineates key niche cells and signals of the developing intestine. Holloway, Czerwinski, Tsai et al. used scRNA-seq to characterize the cellular diversity of the developing human intestinal stem cell niche. Transcriptional and spatial profiling demonstrated that Neuregulin 1 (NRG1) is expressed by PGDFRAHI/F3HI/DLL1HI subepithelial mesenchyme and that NRG1, but not EGF, permitted secretory lineage differentiation in enteroid culture.http://deepblue.lib.umich.edu/bitstream/2027.42/175362/2/Holloway.pdfPublished versionDescription of Holloway.pdf : Published versio

Charting human development using a multi-endodermal organ atlas and organoid models

Organs are composed of diverse cell types that traverse transient states during organogenesis. To interrogate this diversity during human development, we generate a single-cell transcriptome atlas from multiple developing endodermal organs of the respiratory and gastrointestinal tract. We illuminate cell states, transcription factors, and organ-specific epithelial stem cell and mesenchyme interactions across lineages. We implement the atlas as a high-dimensional search space to benchmark human pluripotent stem cell (hPSC)-derived intestinal organoids (HIOs) under multiple culture conditions. We show that HIOs recapitulate reference cell states and use HIOs to reconstruct the molecular dynamics of intestinal epithelium and mesenchyme emergence. We show that the mesenchyme-derived niche cue NRG1 enhances intestinal stem cell maturation in vitro and that the homeobox transcription factor CDX2 is required for regionalization of intestinal epithelium and mesenchyme in humans. This work combines cell atlases and organoid technologies to understand how human organ development is orchestrated.ISSN:0092-8674ISSN:1097-417