Training experience as a limiting factor in master long distance runners

En las últimas décadas ha aumentado el número de atletas veteranos en carreras populares de resistencia. El estudio, que incluyó 103 atletas, tuvo el objetivo de analizar cómo influye la edad y los años de experiencia en el rendimiento de corredores veteranos en largas distancias. Para ello se elaboró un cuestionario ad hoc. El análisis de los años de experiencia muestra correlaciones significativas (p<0,05) en todas las distancias de la categoría de 35-39 años, así como en la distancia de 21,1 km en categoría 40-44 años. Por otro lado, en la comparación entre categorías relacionados con el tiempo total, se encontraron diferencias significativas en la distancia de 21,1 km para los grupos de edad de 35-39/45-49 (p=0,014) y 35-39/50-54 (p=0,014) así como en la distancia de 42,2 km para los grupos de edad de 35-39/45-49 (p=0,022) y 45- 49/50-54 (p=0,050). Los años de experiencia parecen ser un factor limitante del rendimientoIn the last decades, the number of recreational master runners in long-distance running events has increased. This study, which included 103 runners, aimed to analyze the influence of age and training experience on master runners' performance over long distances. An ad hoc questionnaire was used. Training experience analysis showed significant correlations (p<0.05) in all distances in the 35-39 years category, as well as in the distance of 21.1 km in the 40-44 years category. Furthermore, in the comparison between categories related to the total time, significant differences were found in 21.1 km distance for age groups of 35-39 / 45-49 (p=0.014) and 35-39 / 50-54 (p= 0.014) as well as in 42.2 km distance for the age groups of 35-39 / 45-49 (p=0.022) and 45-49 / 50- 54 (p=0.050). Training experience appears to be a limiting factor for performance in recreational master runner

Equivalence of two approaches for the inhomogeneous density in the canonical ensemble

In this article we show that the inhomogeneous density obtained from a density-functional theory of classical fluids in the canonical ensemble (CE), recently presented by White et al [Phys. Rev. Lett. 84 (2000) 1220], is equivalent to first order to the result of the series expansion of the CE inhomogeneous density introduced by Gonzalez et al [Phys. Rev. Lett. 79 (1997) 2466].Comment: 6 pages, RevTe

Low temperature oxide desorption in GaAs (111)A substrates

Trabajo presentado al 17th european Molecular Beam Epitaxy Workshop celebrado en Levi (Finlandia) del 10 al 13 de Marzo de 2013.Peer Reviewe

Change of direction deficit in national team rugby union players: is there an Influence of playing position?

The aim of this study was to investigate the change of direction (COD) ability and deficits of elite rugby union players, discriminating between position (backs and forwards), and between "faster and slower players", in multiple COD tasks. Twenty-four male rugby union players from the Brazilian senior National team completed the following assessments: Squat and countermovement jumps; drop jump; standing long jump, horizontal triple jumps; 40-m linear sprint; Pro-agility, L-Drill, and Zig-zag COD tests; and squat 1-repetition maximum. The differences between backs and forwards and between faster and slower performers were examined using magnitude-based inferences. Backs were faster (in both linear and COD speed tests) and jumped higher than forwards. Moreover, they generated an inferior sprint momentum. No differences were found in COD deficit between playing positions. However, when dividing the sample by median split, faster players outperformed their slower counterparts in all power⁻speed variables and presented higher COD deficits. These results suggest that separating rugby players by playing position might not discriminate players with different COD skills and that the median split analysis is more sensitive to identifying these differences. Furthermore, the present data indicate that faster rugby players are less efficient at changing direction and tolerating higher approach velocities in COD maneuvers

Impact of combined versus single-mode training programs based on drop jump and specific multidirectional repeated sprint on bio-motor ability adaptations: a parallel study design in professional basketball players

Background Jumping and specific multidirectional repeated sprint ability are important in basketball. The objective of this study was to assess the contributions of 8-week combined versus single-mode training programs based on drop jump (DJ) and specific multidirectional repeated sprint (MRSA) on repeated sprint ability performances, body balance and lower limbs power in male professional basketball players. Methods This study followed a randomized parallel study design. Fifty-two professional male basketball players from the Tunisian first division participated in this study. The players were randomly assigned to 4 groups: DJ group (JG; n = 13), MRSA group (RSG; n = 13), combined group (COMB; n = 13) and an active control group (CON; n = 13). The JG, RSG and COMB groups completed the 8-week training programs with 2 sessions per week while the CON continues their regular basketball training. Training volume was similar between groups all over the experimental period. Before and after the intervention, the four groups were evaluated for the stork test, Y-balance test, the repeated sprint ability test (IRSA(5COD)), the squat jump (SJ) and countermovement jump (CMJ) tests, the single leg drop jump test, the five time-jump test and T-change of direction (CoD) test. Results All measures displayed significant main effect, (medium/small) magnitude (effect size) improvements for time (post-test > pre-test) except the physiological parameters for IRSA(5COD). Significant time x group interactions were revealed for body balance, T test, IRSA(5COD) (total time and best time) and jump tests (vertical/horizontal). Bonferroni corrected post-hoc tests revealed significant greater improvement in favor of RSG and COMB compared to JG for body balance, CoD and IRSA(5COD). Moreover, greater improvement in CMJ, SJ and single leg DJ in favor of JG compared to the RSG. In addition, a greater CoD improvement was observed in favor of COMB when compared to the RSG. Conclusion Combined and single-mode training programs based on DJ and MRSA contributed to a significantly better performance in specific basketball physical fitness parameters with results favoring combined interventions

Kinematic and neuromuscular measures of intensity during drop jumps in female volleyball players

The aim of this study was to assess drop jump (DJ) performance variables (jump height, contact time, and reactive strength index) concomitant to surface electromyography (sEMG) of lower limb muscles during DJs from different drop heights (intensities). The eccentric and concentric phase sEMG from the gastrocnemius medialis, biceps femoris, and vastus medialis muscles were assessed during all tests, with sEMG activity normalized to maximal voluntary isometric contraction (MVIC). In a cross-sectional, study, 10 amateur female volleyball players (age 22.1 ± 1.8 years; body mass 72.9 ± 15.2 kg; height 1.70 ± 0.08 m) completed DJs from six heights [15-90 cm (DJ15 to DJ90)]. During DJs there was no jump-target box to rebound on to. Results of one-way analysis of variance (ANOVA) showed that the jump height, contact time, and reactive strength index were not significantly ( \u3e 0.05) different between drop heights. Mean biceps femoris eccentric and concentric sEMG ranged from 27 to 50%, although without significant differences between drop heights. Mean gastrocnemius medialis eccentric and concentric sEMG remained relatively constant (∼60-80% MVIC) across DJs heights, although eccentric values reached 90-120% MVIC from DJ75 to DJ90. Mean variations of ∼50-100% MVIC for eccentric and ∼50-70% MVIC for concentric sEMG activations were observed in the vastus medialis across DJs heights. The biceps femoris eccentric/concentric sEMG ratio during DJ45 (i.e., 1.0) was lower ( = 0.03) compared to the ratio observed after DJ90 (i.e., 3.2). The gastrocnemius medialis and vastus medialis eccentric/concentric sEMG ratio were not significantly different between drop heights. In conclusion, jumping performance and most neuromuscular markers were not sensitive to DJ height (intensity) in amateur female volleyball athletes

Evolución de las capacidades físicas en jugadores jóvenes de baloncesto de medio nivel

El objetivo de estudio fue analizar la evolución de las capacidades físicas de jugadores de medio nivel a lo largo de 2 años (categoría: cadete y júnior). Metodo. 15 jugadores fueron evaluados durante 2 años: en el ultimo año de la etapa cadete (U16) y el primer año de la etapa junior (U18). Los tests fueron realizados en 4 momentos (M) de cada temporada [1.Septiembre (pre-temporada), 2. Diciembre, 3. Abril y 4. Julio, para un total de 8 pruebas]. La batería consistió en un test de 20 m sprint (MST), un test de agilidad T (AGIT), un lanzamiento de balón medicinal de 5 kg (5KGT), un salto (CMJ), un test Sit and Reach (SAR) y la Course Navette (CN). Resultados. Los principales resultados fueron:,los jugadores mejoraron en MST: [1º M: 3.16 ± 0.27 m/s Vs. 4º M: 2.87 ± 0.17 m/s; (p&lt;0.05)]; en CMJ,observamos diferencias estadísticas entre el 1º y 8º M [1º M: 32.57 ± 2.8 cm Vs. 8º M: 42.14 ± 3.8 cm;(p&lt;0.05)]; los resultados en SAR mostraron que los valores decrecieron (1º M: 13.14 ± 12.27 cm al 8º M: 6.42 ± 7.36 cm); finalmente, observamos diferencias significativas entre 1º M y el 8º M en CNT [1º M: 10.36 ± 1.7 paliers Vs. 8º M: 12.5 ± 1.4 paliers; (p&lt;0.05)]. Conclusiones. Se constataron mejoras significativas en las capacidades neuromusculares, la potencia aeróbica y la flexibilidad

The effect of substrate on high-temperature annealing of GaN epilayers: Si versus sapphire

We have studied the effects of rapid thermal annealing at 1300¿°C on GaN epilayers grown on AlN buffered Si(111) and on sapphire substrates. After annealing, the epilayers grown on Si display visible alterations with craterlike morphology scattered over the surface. The annealed GaN/Si layers were characterized by a range of experimental techniques: scanning electron microscopy, optical confocal imaging, energy dispersive x-ray microanalysis, Raman scattering, and cathodoluminescence. A substantial Si migration to the GaN epilayer was observed in the crater regions, where decomposition of GaN and formation of Si3N4 crystallites as well as metallic Ga droplets and Si nanocrystals have occurred. The average diameter of the Si nanocrystals was estimated from Raman scattering to be around 3¿nm. Such annealing effects, which are not observed in GaN grown on sapphire, are a significant issue for applications of GaN grown on Si(111) substrates when subsequent high-temperature processing is required

Running pace decrease during a marathon is positively related to blood markers of muscle damage

Completing a marathon is one of the most challenging sports activities, yet the source of running fatigue during this event is not completely understood. The aim of this investigation was to determine the cause(s) of running fatigue during a marathon in warm weather

Compression stockings do not improve muscular performance during a half‑ironman triathlon race

Purpose This study aimed at investigating the effectiveness of compression stockings to prevent muscular damage and preserve muscular performance during a half-ironman triathlon. Methods Thirty-six experienced triathletes volunteered for this study. Participants were matched for age, anthropometric data and training status and placed into the experimental group (N = 19; using ankle-to-knee graduated compression stockings) or control group (N = 17; using regular socks). Participants competed in a half-ironman triathlon celebrated at 29 ± 3 °C and 73 ± 8 % of relative humidity. Race time was measured by means of chip timing. Pre- and post-race, maximal height and leg muscle power were measured during a countermovement jump. At the same time, blood myoglobin and creatine kinase concentrations were determined and the triathletes were asked for perceived exertion and muscle soreness using validated scales. Results Total race time was not different between groups (315 ± 45 for the control group and 310 ± 32 min for the experimental group; P = 0.46). After the race, jump height (−8.5 ± 3.0 versus −9.2 ± 5.3 %; P = 0.47) and leg muscle power reductions (−13 ± 10 versus −15 ± 10 %; P = 0.72) were similar between groups. Post-race myoglobin (718 ± 119 versus 591 ± 100 μg/mL; P = 0.42) and creatine kinase concentrations (604 ± 137 versus 525 ± 69 U/L; P = 0.60) were not different between groups. Perceived muscle soreness (5.3 ± 2.1 versus 6.0 ± 2.0 arbitrary units; P = 0.42) and the rating of perceived effort (17 ± 2 versus 17 ± 2 arbitrary units; P = 0.58) were not different between groups after the race. Conclusion Wearing compression stockings did not represent any advantage for maintaining muscle function or reducing blood markers of muscle damage during a triathlon event