Phases of the Traditional 505 Test: Between Session and Direction Reliability

Change of direction (COD) testing has commonly reported a single total time to quantify performance despite that tests are made up of a number of different phases. No investigation into these phases has been completed, therefore the aim of this study was to examine the reliability between sessions and directions of the different phases of a 505 test. Twenty-one male youth athletes performed the 505 test in both directions on three occasions. Differences between directions and sessions were determined via a T-test and Two-way ANOVA respectively and a significance threshold was set at P ≤ 0.05. All strategy variables show acceptable relative and absolute reliability in both directions between sessions (ICC = 0.73-0.94; CV = 2.3-6.3%) apart from ground contact time (GCT) (ICC = 0.57-0.68, CV = 14.8–22.4%). Significant differences were identified between session one and three for entry time. Significant differences between directions for exit time on day two and for full approach, entry and GCT on day three. The non-dominant turning direction showed lower relative and absolute reliability between session for entry time (ICC = 0.73 vs 0.89; CV = 6.3% vs 3.7%) and GCT (ICC = 0.57 vs 0.68; CV = 14.8% vs 22.4%). Results indicate the phases of a 505 COD test have high relative and absolute reliability between sessions, although turning directions should be considered independently

An audit of injuries in six English professional soccer academies

Regulations now state that professional academies in the United Kingdom are required to substantially increase the volume of soccer training. This study assessed the current injury occurrence, providing an update to reports published prior to the introduction of the Elite Player Performance Plan (EPPP). 608 soccer players aged 11–18 years from six professional soccer clubs were prospectively monitored, recording injuries during the 2014–2015 season. An injury rate of 1.32 injuries per player/season was indicated with a mean time loss of 21.9 days per injury. The greatest time loss per injury was in the U14s-U15s, and the highest rate of severe injuries in the U15s. Strains and sprains were the most common injury type, with the knee and ankle the most frequently injured anatomical sites. Seasonal variation indicated two peaks in injury incidence, occurring in September and January. In comparison to a published audit prior to the inception of the EPPP, this study indicates that academy soccer players are three-times more likely to experience an injury. Given that time loss and injury severity also increased during periods that typically follow rapid growth, these players should be considered an important group for training load monitoring and injury prevention strategies

Designing Efficient Taxi Pickup Operations at Airports

This paper provides a practical procedure for designing efficient taxi pickup operations at airports. How to do this effectively is an open question. Solutions are not available, and practices vary. They reflect different approaches to and lack of research on the subject. The solutions are often unsatisfactory. At many airports, passengers routinely suffer long waits outdoors, exposed to the elements, after a tiring journey. Such disagreeable experiences are avoidable. Designing efficient taxi pickup operations at airports is problematic. The peculiarities of the process preclude easy solutions. First, the process involves queuing, so system performance is a nonlinear function of the loads. Second, it features unstable transient situations, since travelers typically arrive in bulk over short periods. Third, traffic is significantly differentiated and consists of a wide variety of groups implying different service characteristics. Standard results from queuing theory thus do not have a useful application to this problem. The design process uses simulation that is based on detailed observation of local practices. It involves four steps: (a) detailed local measurements of the arrival of both travelers and taxis, and the service rates provided by taxis in different queuing positions; (b) creation and validation of a simulation model sufficiently detailed to account for these realities; (c) exploration of design alternatives to estimate the characteristics of the service they would provide; and (d) selection of a preferred design that properly balances efforts to minimize average and extreme wait times. The paper demonstrates the procedure through application to Lisbon International Airport, Portugal.SIMUL8 Corporatio

G-Quadruplex Dynamics Contribute To Regulation Of Mitochondrial Gene Expression

Single-stranded DNA or RNA sequences rich in guanine (G) can adopt non-canonical structures known as G-quadruplexes (G4). Mitochondrial DNA (mtDNA) sequences that are predicted to form G4 are enriched on the heavy-strand and have been associated with formation of deletion breakpoints. Increasing evidence supports the ability of mtDNA to form G4 in cancer cells; however, the functional roles of G4 structures in regulating mitochondrial nucleic acid homeostasis in non-cancerous cells remain unclear. Here, we demonstrate by live cell imaging that the G4-ligand RHPS4 localizes primarily to mitochondria at low doses. We find that low doses of RHPS4 do not induce a nuclear DNA damage response but do cause an acute inhibition of mitochondrial transcript elongation, leading to respiratory complex depletion. We also observe that RHPS4 interferes with mtDNA levels or synthesis both in cells and isolated mitochondria. Importantly, a mtDNA variant that increases G4 stability and anti-parallel G4-forming character shows a stronger respiratory defect in response to RHPS4, supporting the conclusion that mitochondrial sensitivity to RHPS4 is G4-mediated. Taken together, our results indicate a direct role for G4 perturbation in mitochondrial genome replication, transcription processivity, and respiratory function in normal cells

In vivo measurements of muscle specific tension in adults and children

This article is available open access through the publisher’s website at the link below. Copyright @ 2009 The Authors.To better understand the effects of pubertal maturation on the contractile properties of skeletal muscle in vivo, the present study investigated whether there are any differences in the specific tension of the quadriceps muscle in 20 adults and 20 prepubertal children of both sexes. Specific tension was calculated as the ratio between the quadriceps tendon force and the sum of the physiological cross-sectional area (PCSA) multiplied by the cosine of the angle of pennation of each head within the quadriceps muscle. The maximal quadriceps tendon force was calculated from the knee extension maximal voluntary contraction (MVC) by accounting for EMG-based estimates of antagonist co-activation, incomplete quadriceps activation using the interpolation twitch technique and magnetic resonance imaging (MRI)-based measurements of the patellar tendon moment arm. The PCSA was calculated as the muscle volume, measured from MRI scans, divided by optimal fascicle length, measured from ultrasound images during MVC at the estimated angle of peak quadriceps muscle force. It was found that the quadriceps tendon force and PCSA of men (11.4 kN, 214 cm2) were significantly greater than those of the women (8.7 kN, 152 cm2; P 0.05) between groups: men, 55 ± 11 N cm−2; women, 57.3 ± 13 N cm−2; boys, 54 ± 14 N cm−2; and girls, 59.8 ± 15 N cm−2. These findings indicate that the increased muscle strength with maturation is not due to an increase in the specific tension of muscle; instead, it can be attributed to increases in muscle size, moment arm length and voluntary activation level

Linearity of the scale for mass and volume within the air displacement plethysmograph (BodPod): A Methodological Investigation

Introduction: In order to maintain the accuracy and reliability for both volume and mass measurements of the air displacement plethysmograph (BodPod) on a day-to-day basis, quality assurance processes are undertaken. Given the importance of accurate estimation of body mass and body volume in determining body composition, the aim of this methodological investigation was to further examine the calibration approaches and to independently determine both the linearity and reliability of mass and volume measurements throughout the potential measurement range. Detailed abstract available to download

NADPH oxidase 2 inhibitors CPP11G and CPP11H attenuate endothelial cell inflammation & vessel dysfunction and restore mouse hind-limb flow.

First described as essential to the phagocytic activity of leukocytes, Nox2-derived ROS have emerged as mediators of a range of cellular and tissue responses across species from salubrious to deleterious consequences. Knowledge of their role in inflammation is limited, however. We postulated that TNFα-induced endothelial reactive oxygen species (ROS) generation and pro-inflammatory signaling would be ameliorated by targeting Nox2. Herein, we in silico-modelled two first-in-class Nox2 inhibitors developed in our laboratory, explored their cellular mechanism of action and tested their efficacy in in vitro and mouse in vivo models of inflammation. Our data show that these inhibitors (CPP11G and CPP11H) disrupted canonical Nox2 organizing factor, p47phox, translocation to Nox2 in the plasma membrane; and abolished ROS production, markedly attenuated stress-responsive MAPK signaling and downstream AP-1 and NFκB nuclear translocation in human cells. Consequently, cell adhesion molecule expression and monocyte adherence were significantly inhibited by both inhibitors. In vivo, TNFα-induced ROS and inflammation were ameliorated by targeted Nox2 inhibition, which, in turn, improved hind-limb blood flow. These studies identify a proximal role for Nox2 in propagated inflammatory signaling and support therapeutic value of Nox2 inhibitors in inflammatory disease

Agreement between methods to determine procedure for maximal exhalation during Hydrostatic Weighing: A Methodological Investigation

Introduction: Current evidence suggests that there are many contentious issues that can impact significantly upon hydrostatic weighing assessments, for instance, obtaining reliable and precise data values within the testing environment [1,2]. Researchers such as Demura et al., [3] have addressed some of these issues, but there is still much uncertainty and significant challenges in terms of the procedure for maximal exhalation during hydrostatic weighing. Therefore, the due to some of these challenges, it was necessary to conduct a methodological investigation to reduce measurement error. Methods: (n = 22) students were recruited from the University of Gloucestershire BSc (Hons) Undergraduate programmes. All participants were over 18 years of age and all were free from disease, illness or injury ( s; age = 20.5 years, body mass = 68.7 kg and stretched stature = 172.0 8.3 cm). Results: When comparing body mass in water values between the two exhalation techniques, (pre-submersion and post-submersion exhalation) results indicated systematic bias (lower value for post-submersion technique). There was a significant difference in body mass values between pre-submersion technique (Mean SD = 2.6 1.2 kg) and post-submersion technique (2.2 1.1 kg), t21 = 4.19 P < 0.01. Conclusion: When using hydrostatic weighing, the post-submersion exhalation technique was associated with greater measurement benefits thus resulting in a more reliable method

Fine structure in the off-resonance conductance of small Coulomb blockade systems

We show how a fine, multiple-peak structure can arise in the off-resonance, zero-bias conductance of Coulomb blockade systems. In order to understand how this effect comes about one must abandon the orthodox, mean-field understanding of the Coulomb blockade phenomenon and consider quantum fluctuations in the occupation of the single-particle electronic levels. We illustrate such an effect with a spinless Anderson-like model for multi-level systems and an equation-of-motion method for calculating Green's functions that combines two simple decoupling schemes.Comment: 5 pages, 3 figures, postscript file also available at http://www.pa.uky.edu/~palacios/papers/eom.ps One figure added. Discussion of results extende