The effects of postactivation potentiation on sprint and jump performance of male academy soccer players.

The purpose of this investigation was to evaluate the postactivation potentiation (PAP) effects of both dynamic and isometric maximum voluntary contractions (MVCs) on sprint and jump performance and establish whether PAP methods could be used effectively in warm up protocols for soccer players. Twelve male soccer players performed 4 warm up protocols in a cross-over, randomized, and counterbalanced design. In addition to a control warm up, subjects performed deadlift (5 repetitions at 5 repetitions maximum), tuck jump (5 repetitions), and isometric MVC knee extensions (3 repetitions for 3 s) as PAP treatments in an otherwise identical warm up protocol. After each treatment, the subjects underwent 3 10 m and 20 m sprints 4, 5, and 6 minutes post-warm up and 3 vertical jumps (VJ) at 7, 8, and 9 minutes post-warm up. Repeated measures analysis of variance showed no significant differences in the first 10 m (p = 0.258) and 20 m (p = 0.253) sprint and VJ (p = 0.703) performance and the average 10 m (p = 0.215), 20 m (p = 0.388), and VJ (p = 0.529) performance between conditions. There were also no significant differences in performance responses between the strongest and weakest subjects, but large variations in individual responses were found between the subjects. The findings suggest that there was no significant group PAP effect on sprint and jump performance after dynamic and isometric MVCs compared with a control warm up protocol. However, the large variation in individual responses (-7.1% to +8.2%) suggests PAP should be considered on an individual basis. Factors such as method, volume, load, recovery, and interindividual variability of PAP must be considered in the practical application of PAP and the rigorous research design of future studies to evaluate the potential for performance enhancement

Curating NASA's Extraterrestrial Samples - Past, Present, and Future

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. The Astromaterials Acquisition and Curation Office at the NASA Johnson Space Center (JSC) is responsible for curating NASA s extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10E "Curation of Extraterrestrial Materials", JSC is charged with ". . . curation of all extraterrestrial material under NASA control, including future NASA missions." The Directive goes on to define Curation as including "documentation, preservation, preparation, and distribution of samples for research, education, and public outreach.

Simulation of a storm event in marine microcosms

A storm of moderate intensity and lasting for 14 hours was simulated in three of the Marine Ecosystems Research Laboratory (MERL) microcosms by increasing the intensity of microcosm mixing. The simulation resuspended ~0.3 cm of sediment and increased suspended particulate loads by 2 orders of magnitude. Concurrently, the concentrations of metals and nutrients increased in the water column...

Phosphoregulation of HORMA domain protein HIM-3 promotes asymmetric synaptonemal complex disassembly in meiotic prophase in Caenorhabditis elegans

正常な精子・卵子の形成メカニズムを解明 --染色体の分離に重要なタンパク質の発見--. 京都大学プレスリリース. 2020-12-04.In the two cell divisions of meiosis, diploid genomes are reduced into complementary haploid sets through the discrete, two-step removal of chromosome cohesion, a task carried out in most eukaryotes by protecting cohesion at the centromere until the second division. In eukaryotes without defined centromeres, however, alternative strategies have been innovated. The best-understood of these is found in the nematode Caenorhabditis elegans: after the single off-center crossover divides the chromosome into two segments, or arms, several chromosome-associated proteins or post-translational modifications become specifically partitioned to either the shorter or longer arm, where they promote the correct timing of cohesion loss through as-yet unknown mechanisms. Here, we investigate the meiotic axis HORMA-domain protein HIM-3 and show that it becomes phosphorylated at its C-terminus, within the conserved “closure motif” region bound by the related HORMA-domain proteins HTP-1 and HTP-2. Binding of HTP-2 is abrogated by phosphorylation of the closure motif in in vitro assays, strongly suggesting that in vivo phosphorylation of HIM-3 likely modulates the hierarchical structure of the chromosome axis. Phosphorylation of HIM-3 only occurs on synapsed chromosomes, and similarly to other previously-described phosphorylated proteins of the synaptonemal complex, becomes restricted to the short arm after designation of crossover sites. Regulation of HIM-3 phosphorylation status is required for timely disassembly of synaptonemal complex central elements from the long arm, and is also required for proper timing of HTP-1 and HTP-2 dissociation from the short arm. Phosphorylation of HIM-3 thus plays a role in establishing the identity of short and long arms, thereby contributing to the robustness of the two-step chromosome segregation

Variable and changing trajectories in youth athlete development: further verification in advocating a long-term inclusive tracking approach.

Athlete development through adolescence can vary greatly because of maturational processes. For example, variation can be observed in anthropometric and fitness measures with later maturing individuals "catching up" their earlier maturing peers at later time points. This study examined a methodological issue concerning how best to assess anthropometric and fitness change (i.e., "across age categories" or "per year") relative to an age and skill-matched population (N = 1,172). Furthermore, it examined changes in anthropometric and fitness characteristics in 3 cases of youth rugby league players (aged 13-15) across a 2-year period. Findings identified the "per year" method as generating less deviated z-scores across anthropometric and fitness measures (e.g., mean change p < 0.001), suggesting less substantial change in case players relative to the population. When applied to additional players, z-score and radar graphs showed developmental variability and longitudinal change. The possibility of a "later maturing player" increasing anthropometric (e.g., height: player 4 = 3.3 cm; player 5 = 13.2 cm; and player 6 = 15.7 cm) and fitness (e.g., 30-m sprint: player 4 = -0.18 s, player 5 = -0.46 s, and player 6 = -0.59 s) characteristics compared with early maturing players was confirmed. Findings affirm the potential for variable and changing trajectories in adolescent athletes. Practical implications advocate a long-term inclusive tracking approach of athletes, the avoidance of (de)selection, and the reduction of a performance emphasis in adolescent stages of sport systems

Using anthropometric and performance characteristics to predict selection in junior UK Rugby League players.

Research examining the factors influencing selection within talented junior Rugby League players is limited. The aims of this study were firstly to determine whether differences existed for anthropometric and performance characteristics between regional and national selection in high performance UK junior Rugby League players, and secondly to identify variables that discriminated between these selection levels. Regional representative (n=1172) selected junior players (aged 13-16 years) undertook an anthropometric and fitness testing battery with players split according to selection level (i.e., national, regional). MANCOVA analyses, with age and maturation controlled, identified national players as having lower sum of 4 skinfolds scores compared to regional players, and also performed significantly better on all physical tests. Stepwise discriminant analysis identified that estimated maximum oxygen uptake (VO2max), chronological age, body mass, 20 m sprint, height, sum of 4 skinfolds and sitting height discriminated between selection levels, accounting for 28.7% of the variance. This discriminant analysis corresponded to an overall predictive accuracy of 63.3% for all players. These results indicate that performance characteristics differed between selection levels in junior Rugby League players. However, the small magnitude of difference between selection levels suggests that physical qualities only partially explain higher representative selection. The monitoring and evaluation of such variables, alongside game related performance characteristics, provides greater knowledge and understanding about the processes and consequences of selection, training and performance in youth sport

Seasonal changes in anthropometric and physical characteristics within English academy rugby league players.

Professional rugby league clubs implement training programmes for the development of anthropometric and physical characteristics within an academy programme. However, research that examines seasonal changes in these characteristics is limited. The purpose of the study was to evaluate the seasonal changes in anthropometric and physical characteristics of academy rugby league players by age category (i.e., under 14, 16, 18, 20). Data were collected on 75 players pre- and postseason over a 6-year period (resulting in a total of 195 assessments). Anthropometric (body mass, sum of 4 skinfolds) and physical (10- and 20-m sprint, vertical jump, Yo-Yo intermittent recovery test and 1 repetition maximum squat, bench press, and prone row) measures were collected. The under 14s and 16s showed greater seasonal improvements in body mass (e.g., under 14s = 7.4 ± 4.3% vs. under 20s = 1.2 ± 3.3%) and vertical jump performance than under 18s and under 20s. In contrast, under 18s and under 20s players showed greater seasonal improvements in Yo-Yo performance and 10-m sprint (e.g., under 14s = 1.3 ± 3.9% vs. under 20s = -1.9 ± 1.2%) in comparison to under 14s and under 16s. Seasonal strength improvements were greater for the under 18s compared with under 20s. This study provides comparative data for seasonal changes in anthropometric and physical characteristics within rugby league players aged 13-20 years. Coaches should be aware that seasonal improvements in speed may not exist within younger age categories, until changes in body mass stabilize and consider monitoring changes in other characteristics (e.g., momentum). Large interplayer variability suggests that player development should be considered on an individual and longitudinal basis

Anthropometric and physical characteristics of english academy rugby league players.

The purpose of the present study was to evaluate the anthropometric and physical characteristics of English academy rugby league players by annual-age category (under 16s-under 20s) and between backs and forwards. Data were collected on 133 academy players over a 6-year period (resulting in a total of 257 assessments). Player assessments comprised of anthropometric (height, body mass, sum of 4 skinfolds) and physical (vertical jump, 10- and 20-m sprint, estimated V[Combining Dot Above]O2max via the yo-yo intermittent recovery test level 1, absolute 1 repetition maximum [1RM], and relative squat, bench press, and prone row) measures. Univariate analysis of variance demonstrated significant (p ≤ 0.05) increases in height, body mass, vertical jump, absolute, and relative strength measures across the 5 annual-age categories (e.g., body mass: under 16s = 75.2 ± 11.1, under 20s = 88.9 ± 8.5 kg; vertical jump: under 16s = 45.7 ± 5.2, under 20s = 52.8 ± 5.4 cm; 1RM bench press: under 16s = 73.9 ± 13.2, under 20s = 114.3 ± 15.3 kg). Independent t-tests identified significant (p ≤ 0.05) differences between backs and forwards for anthropometric (e.g., under 16s body mass: backs = 68.4 ± 8.6, forwards = 80.9 ± 9.7 kg) and physical (e.g., under 19s 20-m sprint: backs = 3.04 ± 0.08, forwards = 3.14 ± 0.12s; under 18s relative squat: backs = 1.65 ± 0.18, forwards = 1.51 ± 0.17 kg·kg) characteristics that were dependent on the age category and measure assessed. Findings highlight that anthropometric and physical characteristics develop across annual-age categories and between backs and forwards in academy rugby league players. These findings provide comparative data for such populations and support the need to monitor player development in junior rugby league players