Efficacy of a four-week uphill sprint training intervention in field hockey players

Current evidence increasingly suggests that very short, supra-maximal bouts of exercise can have significant health and performance benefits. The majority of research conducted in the area however, uses laboratory-based protocols, which can lack ecological validity. The purpose of this study was to examine the effects of a high intensity sprint-training programme on hockey related performance measures. 14 semi-professional hockey players completed either a 4-week high intensity training (HIT) intervention, consisting of a total of six sessions HIT, which progressively increased in volume (n=7), or followed their normal training programme (Con; n=7). Straight-line sprint speed with and without a hockey stick and ball, and slalom sprint speed, with and without a hockey stick and ball were used as performance indicators. Maximal sprint speed over 22.9m was also assessed. Upon completion of the four-week intervention, straight-line sprint speed improved significantly in the HIT group (~3%), with no change in performance for the Con group. Slalom sprint speed, both with and without a hockey ball was not significantly different following the training programme in either group. Maximal sprint speed improved significantly (12.1%) in the HIT group, but there was no significant performance change in the Con group. The findings of this study indicate that a short period of HIT can significantly improve hockey related performance measures, and could be beneficial to athletes and coaches in field settings

Identification-based Diagnosis of Rainfall ¿Stream Flow Data: the Tinderry Catchment

System identification tools, such as transfer function (TF) model structure identification, recursive estimation, time-varying parameter (TVP) estimation and assessment of data information, are used to evaluate the quality of rainfall-stream flow data from the Tinderry catchment (ACT, Australia) and the timevarying behaviour of the rainfall-stream flow dynamics. For the catchment, given the wide range and the abrupt changes of the single input-single output transfer functions describing different periods or events, we conclude that further investigation of (i) local rainfall effects, (ii) time-varying time delays (travelling time), (iii) time-varying residence times related to the base flow and (iv) occurrence of negative residues is needed. Periods with high and low data information content, for further use in effective parameter estimation procedures, are clearly indicated by the analysis

IWRAM: An integrated toolbox for considering impacts of development and land use change in Northern Thailand

The IWRAM Decision Support System was developed to consider economic, environmental, and sociocultural trade-offs involved with resource competition and development in the Mae Chaem catchment in Northern Thailand. IWRAM contains two modelling toolboxes utilising a nodal network structure for catchment analysis: a Biophysical Toolbox, for considering the biophysical (erosion, streamflow, crop) implications of 'painted on' land use scenarios; and, an Integrated Modelling Toolbox, which links models of household decision making with the biophysical toolbox to allow for consideration of socioeconomic and environmental trade-offs of many development and policy scenarios. This paper describes the Integrated Modelling Toolbox within the IWRAM system. Links between household decision models, a socioeconomic impacts model and the biophysical toolbox are described and results for a number of forest encroachment scenarios are demonstrated using key indicators of social, economic and environmental performance. The potential for reapplication of the modelling framework to a large number of catchment situations is also discussed. (Résumé d'auteur

Effect of an acute dose of omega-3 fish oil following exercise-induced muscle damage

Purpose The purpose of this double-blind, placebo-controlled study was to examine the effect of two fish oil supplements, one high in EPA (750 mg EPA, 50 mg DHA) and one low in EPA (150 mg EPA, 100 mg DHA), taken acutely as a recovery strategy following EIMD. Methods Twenty-seven physically active males (26 ± 4 year, 1.77 ± 0.07 m, 80 ± 10 kg) completed 100 plyometric drop jumps to induce muscle damage. Perceptual (perceived soreness) and functional (isokinetic muscle strength at 60° and 180° s−1, squat jump performance and countermovement jump performance) indices of EIMD were recorded before, and 1, 24, 48, 72, and 96h after the damaging protocol. Immediately after the damaging protocol, volunteers ingested either a placebo (Con), a low-EPA fish oil (Low EPA) or a high-EPA fish oil (High EPA) at a dose of 1 g per 10 kg body mass. Results A significant group main effect was observed for squat jump, with the High EPA group performing better than Con and Low EPA groups (average performance decrement, 2.1, 8.3 and 9.8%, respectively), and similar findings were observed for countermovement jump performance, (average performance decrement, 1.7, 6.8 and 6.8%, respectively, p = 0.07). Significant time, but no interaction main effects were observed for all functional and perceptual indices measured, although large effect sizes demonstrate a possible ameliorating effect of high dose of EPA fish supplementation (effect sizes ≥0.14). Conclusion This study indicates that an acute dose of high-EPA fish oil may ameliorate the functional changes following EIMD

On random flights with non-uniformly distributed directions

This paper deals with a new class of random flights $\underline{\bf X}_d(t),t>0,$ defined in the real space $\mathbb{R}^d, d\geq 2,$ characterized by non-uniform probability distributions on the multidimensional sphere. These random motions differ from similar models appeared in literature which take directions according to the uniform law. The family of angular probability distributions introduced in this paper depends on a parameter $\nu\geq 0$ which gives the level of drift of the motion. Furthermore, we assume that the number of changes of direction performed by the random flight is fixed. The time lengths between two consecutive changes of orientation have joint probability distribution given by a Dirichlet density function. The analysis of $\underline{\bf X}_d(t),t>0,$ is not an easy task, because it involves the calculation of integrals which are not always solvable. Therefore, we analyze the random flight $\underline{\bf X}_m^d(t),t>0,$ obtained as projection onto the lower spaces $\mathbb{R}^m,m<d,$ of the original random motion in $\mathbb{R}^d$. Then we get the probability distribution of $\underline{\bf X}_m^d(t),t>0.$ Although, in its general framework, the analysis of $\underline{\bf X}_d(t),t>0,$ is very complicated, for some values of $\nu$, we can provide some results on the process. Indeed, for $\nu=1$, we obtain the characteristic function of the random flight moving in $\mathbb{R}^d$. Furthermore, by inverting the characteristic function, we are able to give the analytic form (up to some constants) of the probability distribution of $\underline{\bf X}_d(t),t>0.$Comment: 28 pages, 3 figure

Intensity distribution for waves in disordered media: deviations from Rayleigh statistics

We study the intensity distribution function, P(I), for monochromatic waves propagating in quasi one-dimensional disordered medium, assuming that a point source and a point detector are embedded in the bulk of the medium. We find deviations from the Rayleigh statistics at moderately large I and a logarithmically-normal asymptotic behavior of P(I). When the radiation source and the detector are located close to the opposite edges of the sample (on a distance much less then the sample length), an intermediate regime with a stretched-exponential behavior of P(I) emerges.Comment: 4 pages Revtex, 3 figures included as eps file