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Samuel Ryan, Emidio Pacecca, Jye Tebble, Joel Hocking, Thomas Kempton and Aaron J. Coutts

changes in that test. 13 Using the CV%, the sensitivity of a test can be established via signal to noise ratio (SNR) analysis. 12 Indeed, measurement signal is often assessed via intervention studies where responsiveness (ie, a change in performance) is measured following the intervention 14 ; however

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Xingda Qu, Jianxin Jiang and Xinyao Hu

resonance theory, 11 many researchers have recently found that subsensory noise is able to enhance the sensitivity of the human proprioception. 12 , 13 For instance, Toledo et al 13 reported that detection time for passive joint movement was reduced by the addition of subsensory noise in both young and

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Carly C. Sacco, Erin M. Gaffney and Jesse C. Dean

for improving postural control. One possible method to enhance sensory feedback involves stochastic resonance, a phenomenon by which low-amplitude noise increases the likelihood that weak signals will exceed a given threshold, improving detection of signal fluctuations. 9 , 10 Such sensation

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Christian Unkelbach and Daniel Memmert

The home advantage is one of the best established phenomena in sports (Courneya & Carron, 1992), and crowd noise has been suggested as one of its determinants (Nevill & Holder, 1999). However, the psychological processes that mediate crowd noise influence and its contribution to the home advantage are still unclear. We propose that crowd noise correlates with the criteria referees have to judge. As crowd noise is a valid cue, referee decisions are strongly influenced by crowd noise. Yet, when audiences are not impartial, a home advantage arises. Using soccer as an exemplar, we show the relevance of this influence in predicting outcomes of real games via a database analysis. Then we experimentally demonstrate the influence of crowd noise on referees’ yellow cards decisions in soccer. Finally, we discuss why the focus on referee decisions is useful, and how more experimental research could benefit investigations of the home advantage.

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Ruud J. R. Den Hartigh, Ralf F. A. Cox, Christophe Gernigon, Nico W. Van Yperen and Paul L. C. Van Geert

The aim of this study was to examine (1) the temporal structures of variation in rowers’ (natural) ergometer strokes to make inferences about the underlying motor organization, and (2) the relation between these temporal structures and skill level. Four high-skilled and five lower-skilled rowers completed 550 strokes on a rowing ergometer. Detrended Fluctuation Analysis was used to quantify the temporal structure of the intervals between force peaks. Results showed that the temporal structure differed from random, and revealed prominent patterns of pink noise for each rower. Furthermore, the high-skilled rowers demonstrated more pink noise than the lower-skilled rowers. The presence of pink noise suggests that rowing performance emerges from the coordination among interacting component processes across multiple time scales. The difference in noise pattern between high-skilled and lower-skilled athletes indicates that the complexity of athletes’ motor organization is a potential key characteristic of elite performance.

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Maria W.G. Nijhuis-Van der Sanden, Edwin H.F. Van Asseldonk, Paul A.T.M. Eling and Gerard P. Van Galen

This study examined the relationship between decreased speed-accuracy tradeoff and increased neuromotor noise in girls with Turner Syndrome (TS). Fifteen girls with TS and 15 age-matched controls performed isometric force contractions with both index fingers separately at 5 force levels, based on their maximum voluntary contraction. The results revealed that (a) groups did not differ in speed-accuracy tradeoff or neuromotor noise, (b) output-variability increased linearly with force level, (c) signal-to-noise ratio changed according to an inverted U-shaped function, (d) broadening in the frequency profile is highest at the lower force levels, (e) with increasing force level, the power peak in the 0–4 Hz domain dominates, (f) frequency profile broadens more in the dominant hand. These findings suggest that, in girls with TS, motor performance is not diminished in an isometric force task, that motor recruitment is intact, and that neuromotor noise is not increased. The findings are discussed with respect to motor control and neuromotor noise.

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Bing Yu, David Gabriel, Larry Noble and Kai-Nan An

The purposes of this study were (a) to develop a procedure for objectively determining the optimum cutoff frequency for the Butterworth low-pass digital filler, and (b) to evaluate the cutoff frequencies derived from the residual analysis. A set of knee flexion-extension angle data in normal gait was used as the standard data set. The standard data were sampled at different sampling frequencies. Random errors with different magnitudes were added to the standard data to create different sets of raw data with a given sampling frequency. Each raw data set was filtered through a Butterworth low-pass digital filter at different cutoff frequencies. The cutoff frequency corresponding to the minimum error in the second time derivatives for a given set of raw data was considered as the optimum for that set of raw data. A procedure for estimating the optimum cutoff frequency from the sampling frequency and estimated relative mean error in the raw data set was developed. The estimated optimum cutoff frequency significantly correlated to the true optimum cutoff frequency with a correlation determinant value of 0.96. This procedure was applied to estimate the optimum cutoff frequency for another set of kinematic data. The calculated accelerations of the filtered data essentially matched the measured acceleration curve. There is no correlation between the cutoff frequency derived from the residual analysis and the true optimum cutoff frequency. The cutoff frequencies derived from the residual analysis were significantly lower than the optimum, especially when the sampling frequency is high.

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Marc R. Portus, David G. Lloyd, Bruce C. Elliott and Neil L. Trama

The measurement of lumbar spine motion is an important step for injury prevention research during complex and high impact activities, such as cricket fast bowling or javelin throwing. This study examined the performance of two designs of a lumbar rig, previously used in gait research, during a controlled high impact bench jump task. An 8-camera retro-reflective motion analysis system was used to track the lumbar rig. Eleven athletes completed the task wearing the two different lumbar rig designs. Flexion extension data were analyzed using a fast Fourier transformation to assess the signal power of these data during the impact phase of the jump. The lumbar rig featuring an increased and pliable base of support recorded moderately less signal power through the 0–60 Hz spectrum, with statistically less magnitudes at the 0–5 Hz (p = .039), 5–10 Hz (p = .005) and 10–20 Hz (p = .006) frequency bins. A lumbar rig of this design would seem likely to provide less noisy lumbar motion data during high impact tasks.

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Jian Chen, Bruce Oddson and Heather C. Gilbert

as described previously. 12 The 2 sensitivity symptoms (to light and to noise) were also tested as a cluster. To form and compare composite scores of the symptom groups, individual scale items were rated using the graded symptom scores. The composite scores were compared using t test. The Mann

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Evangelos Galanis, Antonis Hatzigeorgiadis, Nikos Comoutos, Fedra Charachousi and Xavier Sanchez

include factors such as intrusive thoughts (e.g., worrying), emotions (e.g., anger), and even bodily sensations (e.g., fatigue); whereas, external sources include factors such as visual triggers (e.g., crowd movements), auditory triggers (e.g., crowd noises), gamesmanship by opponents (e.g., verbal