1,720,966 research outputs found
Effects of differential jump training on balance performance in female volleyball players
Full text linkThe purpose of this study was to determine whether coordinative jump training that induces neuromuscular stimuli can affect balance performance, associated with injury risk, in elite-level female volleyball players. During the competitive season, the balance performance of 12 elite female players (highest Austrian division) was obtained via a wobble board (WB; 200 Hz) placed on an AMTI force plate (1000 Hz). Three identically repeated measurements defined two intervals (control and intervention phases), both comparable in duration and regular training. The intervention included 6 weeks of differential training (8 sessions of 15–20 min) that delivered variations in dynamics around the ankle joints. Multilevel mixed models were used to assess the effect on postural control. WB performance decreased from 27.0 ± 13.2% to 19.6 ± 11.3% during the control phase and increased to 54.5 ± 16.2% during the intervention (β = 49.1 ± 3.5; p < 0.001). Decreased sway area [cm²] (β = −7.5 ± 1.6; p < 0.001), anterior–posterior (β = −4.1 ± 0.4; p < 0.001) and mediolateral sway [mm] (β = −2.7 ± 0.6; p = 0.12), and mean velocity [mm∙s−1] (β = −9.0 ± 3.6; p < 0.05) were observed during the intervention compared with the control phase. Inter-limb asymmetry was reduced (β = −41.8 ± 14.4; p < 0.05). The applied training concept enhanced balance performance and postural control in elite female volleyball players. Due to the low additional physiological loads of the program and increased injury risk during the competitive season, we recommend this intervention for supporting injury prevention during this period
Wobble board balance assessment in subjects with chronic ankle instability
No full textBackground: Wobble boards (WBs), commonly used to train postural control, have been recently equipped with accelerometers connected to a computer displaying real-time balance performances. However, little is known about their ability to detect balance deficits in subjects with unilateral chronic ankle instability (CAI).Objective: To determine if computerized WBs can detect balance deficits in subjects with unilateral CAI.Methods: Fifteen subjects with unilateral CAI and fifteen uninjured subjects performed one WB test and one Y Balance Test (YBT) during two separate randomized sessions. WB performance was assessed as the time (s) spent on the platform by keeping it flat at 0 degrees during three 30-s trials for each limb. Normalized (%) reach distances values for anterior, posteromedial, posterolateral directions and composite were recorded for YBT.Results: WB has been shown to be a reliable and accurate device for detecting balance deficits between and within subjects with unilateral CAI. The area under the curve for receiver operating characteristic was 0.80 (asymptotic significance 0.001), suggesting that WBs have the capability to accurately discriminate between injured and uninjured limbs.Significance: Computerized WBs can fill the gap caused by limitations between subjective-based clinical assessment and laboratory-based testing, especially in field-based settings, where specificity, transportability and time constraints are crucial. The results of the present study suggest that WBs may facilitate the detection of balance impairments in subjects with unilateral CAI, without complexity in its use or data interpretation
A novel approach to measuring wobble board performance in individuals with chronic ankle instability
No full textComputerized wobble boards (WB) are used to objectively assess balance in healthy and chronic ankle instability individuals. As in field setting health professionals might not own WB, objective evaluations are not always feasible. Therefore, the aim of this tudy was to investigate the contribution of sagittal plane joints angular-displacement and anthropometrics to predict equations to estimate WB performance by portable two-dimensional motion analysis (2D-MA) and cross-validate the developed equations in chronic ankle instability individuals. Thirty-nine healthy and twenty chronic ankle instability individuals stood on a WB in single stance position. The balance test consisted of three 30s trials per limb keeping the platform flat at 0°. Trials were video recorded, and three time-segments joints angular-displacement analyzed with 2D-MA: segment 1 (T1) including 30s data, segment 2 (T2) from second 0 to 10, segment 3 (T3) only the first 5s. Mixed regression for multilevel models was used to estimate WB performance for each time-segment and to examine limb differences for the predicted WB performance in chronic ankle instability sample. The accuracy of the equations to detect injured limbs was calculated via area under the curve for receiver operating characteristic. Ankle and knee angular-displacement parameters, body height and lower limb length were the major predictors of WB performance for the extrapolated models (p < 0.05; R2 = 0.83–0.56). The measured WB performance and T1 model showed significant (p < 0.05) performance differences between the injured and uninjured limbs. Receiver operating characteristic analysis showed an asymptotic significance of 0.03 for T1 equation with area under the curve of 0.70. The proposed models provide different methods to quantify the performance and accurately detect the injured limb in individuals with unilateral chronic ankle instability, when measuring balance via WB might not be feasible. App-makers may use the equations to provide an automatic all-in-one system to monitor the performance status and progress.Andrea Fusco, Philip X. Fuchs, Marianna De Maio, Herbert Wagner, Cristina Corti
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Establishing the Locomotor Performance Profile of Elite Ladies Gaelic Football across Position and Quarters
Full text linkThe aim of the current investigation was to examine the locomotor performance profile of elite ladies Gaelic football (LGF) players in relation to playing position and quarters of play. Thirty (n = 30) elite LGF players (age: 24 ± 4 years, height: 169 ± 5 cm, body mass: 61 ± 4 kg) were monitored using 10 Hz GPS technology (Playertek; Catapult Sports; Australia) resulting in 145 individual samples collected over 18 competitive matches across the 2021 and 2022 LGF seasons. Locomotor performance was determined across the following variables: total distance covered (TD, m), relative distance (m·min−1), high-speed running (HSR, ≥ 4.4 m·s−1), very high-speed running (VHSR, ≥ 5.5 m·s−1), relative HSR (RHSR; m·min−1), peak velocity (m·s−1), percentage peak velocity (%PeakV), accelerations (n; ≥ 3 m·s−2), and decelerations (n; ≤ −3 m·s−2). Data were classified based on playing position and quarter of play. The greatest TD was covered by half-backs, midfielders, and half-forwards, with these positions covering significantly greater distances than full-backs (p < 0.05). Similarly, half-backs, midfielders, and half-forwards covered the greatest high-speed distance (HSR). When running performance was analysed across quarters, a significant position by quarter interaction was observed for all running performance variables, except peak velocity and percentage peak velocity. A consistent trend for reduced locomotor performance was evident in the second and fourth quarters across all positional lines. The current data provide coaches with the position-specific locomotor requirements of LGF match-play, which can inform the design of training content for LGF players, along with match-day strategies. Given the reduction in locomotor performance observed across the match, performance staff may consider the use of nutritional interventions, rewarm-up strategies, or specific substitution policies to mitigate the decrement in locomotor performance observed across match-play
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