Correction to “Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate”

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): B04299, doi:10.1029/2009JB006451

The effects of a 6-week strength training on critical velocity, anaerobic running distance, 30-m sprint and yo-yo intermittent running test performances in male soccer players

The objectives of this study were to examine the effects of a moderate intensity strength training on changes in critical velocity (CV), anaerobic running distance (D'), sprint performance and Yo-Yo intermittent running test (Yo-Yo IR1) performances. Methods: two recreational soccer teams were divided in a soccer training only group (SO; n = 13) and a strength and soccer training group (ST; n = 13). Both groups were tested for values of CV, D', Yo-Yo IR1 distance and 30-m sprint time on two separate occasions (pre and post intervention). The ST group performed a concurrent 6-week upper and lower body strength and soccer training, whilst the SO group performed a soccer only training. Results: after the re-test of all variables, the ST demonstrated significant improvements for both, YoYo IR1 distance (p = 0.002) and CV values (p<0.001) with no significant changes in the SO group. 30-m sprint performance were slightly improved in the ST group with significantly decreased performance times identified in the SO group (p<0.001). Values for D' were slightly reduced in both groups (ST -44.5 m, 95% CI = -90.6 to 1.6; SO -42.6 m, 95% CI = -88.7 to 3.5). Conclusions: combining a 6-week moderate strength training with soccer training significantly improves CV, Yo-Yo IR1 whilst moderately improving 30-m sprint performances in non-previously resistance trained male soccer players. Critical Velocity can be recommended to coaches as an additional valid testing tool in soccer

Yo-Yo IR2 test e teste de margaria: validade, confiabilidade e obtenção da frequência cardíaca máxima em jogadores jovens de futebol

Os objetivos do presente estudo foram: i) avaliar a validade de constructo do Yo-Yo Intermittente Recovery Test Level 2 (Yo-Yo IR2) e do teste de Margaria (TM) com o desempenho em alta intensidade de exercício durante jogos oficiais em jogadores de futebol; ii) verificar a confiabilidade (teste-reteste) dos dois testes; iii) comparar os valores da frequência cardíaca máxima (FCM) obtida nesses protocolos e em jogo. Dezoito jogadores (média ± DP; idade 14 ± 0,8 anos, estatura 172 ± 9cm, peso 64,3 ± 8,5kg) pertencentes à mesma equipe foram avaliados em teste-reteste nos referidos protocolos e no percentual de tempo de permanência acima de 85% da FCM individual (PTP>85%FCM) em dois jogos oficiais do Campeonato Mineiro Infantil. Uma alta correlação foi encontrada entre o desempenho no Yo-Yo IR2 e PTP>85%FCM (rs = 0,71; p 85%FCM (rs = 0,44; p = 0,06). O Yo-Yo IR2 se mostrou mais variável e menos reprodutível (CV = 11%; CCI [95% IC] = 0,38) do que TM (CV = 1%; CCI [95% IC] = 0,93). O maior valor de FCM (p < 0,001) ocorreu no jogo (202 ± 8bpm). A FCM no Yo-Yo IR2 (194 ± 4bpm) foi menor (p < 0,006) do que TM (197 ± 6bpm). Conclui-se que o Yo-Yo IR2 pode ser considerado mais válido para predizer a manutenção de alta intensidade de exercício em jogo que é uma importante medida de desempenho no futebol. Porém, há necessidade de padronização rigorosa entre os procedimentos de avaliação para estabilidade da medida. A FCM deve ser observada em diversas situações, principalmente competitiva, para possibilitar que ocorra o maior valor individual

Laboratory measurements of compressional and shear wave speeds through methane hydrate

Simultaneous measurements of compressional and shear wave speeds through polycrystalline methane hydrate have been made. Methane hydrate, grown directly in a wave speed measurement chamber, was uniaxially compacted to a final porosity below 2%. At 277 K, the compacted material's compressional wave speed was 3650 {+-} 50 m/s. The shear wave speed, measured simultaneously, was 1890 {+-} 30 m/s. From these wave speed measurements, we derive Vp/Vs, Poisson's Ratio, bulk, shear and Young's moduli

The reliability of running economy among trained distance runners and field-based players

Whilst the reliability of running economy (RE) has been widely established, there is limited investigation of the reliability of various performance variables during a RE test. Subsequently, the purpose of the current study was to examine the reliability of time-to-exhaustion (TTE) and rating of perceived exertion (RPE) during a RE test amongst trained runners (TR) and moderately endurance trained men (METM). Absolute V̇O2 (ml.min-1), V̇O2 relative to body mass (ml.kg-1.min-1), oxygen cost of running (CR) defined as V̇O2 relative to body mass raised to the power of 0.75 and metre (ml.kg-0.75.m-1), heart rate (HR), ventilation (V̇E), carbon dioxide production (V̇CO2), respiratory exchange ratio (RER) and RPE were measured whilst treadmill running on two occasions at three discontinuous incremental speeds corresponding to 70-, 90- and 110% of the second ventilatory threshold (VT2). The duration of the last increment was measured as TTE. The reliability was determined using intra-class correlation coefficient (ICC) and 95% ratio limits of agreement. The intra-individual variability was examined using coefficient of variation (CV). There were no significant differences between the two RE trials for absolute V̇O2, relative V̇O2, CR, V̇E, V̇CO2, RER and RPE (P ≥ 0.05) except for differences in RPE during the first increment and TTE (P < 0.05). The reliability was high for absolute O2, relative O2, CR, HR and TTE and moderate for V̇E and RPE. Small intra-individual variability was found for absolute V̇O2, relative V̇O2, CR, HR and RPE. The findings will enable sport scientists to incorporate a variety of performance variables when examining RE