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Øyvind Skattebo and Thomas Losnegard

major international championships (Olympics and World Championships) and World Cup (WC) races could be beneficial for evaluation and optimization of training preparation. Thus, the aims of the present study were to estimate the variability and predictability in skiing time, shooting time, proportion of

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Arturo Forner-Cordero, Virgínia H. Quadrado, Sitsofe A. Tsagbey and Bouwien C.M. Smits-Engelsman

load can improve the learning process of this task, three different types of loading conditions were applied to three groups of participants. In the first group, the load was applied by a constant spring representing a predictable load (PL). In the second group, a variable load was applied by changing

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Kathryn E. Phillips and Will G. Hopkins

-to-tournament within the season were estimated, with cyclist identity and the residual as the only random effects in each model. Tournament identity was again included as a fixed effect to adjust for any differences in mean caliber of athlete between tournaments. The predictability of athlete performance was

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Kathryn E. Phillips and Will G. Hopkins

Purpose:

To explore the extent to which factors that determine performance transfer within and between time-trial and mass-start events in the track-cycling Omnium.

Methods:

Official finish rank in the 3 time-trial events, in the 3 mass-start events, and in the competition overall were collated in 20 international Omnium competitions between 2010 and 2014 for 196 male and 140 female cyclists. Linear mixed modeling of the log-transformed finish time for the time-trial events and of log-transformed finish rank for all events and final rank provided estimates of within-athlete race-to-race changes in performance and average betweenathletes differences across a season. These estimates were converted to various correlations representing relationships within and between the various events and final rank.

Results:

Intraclass correlation coefficients, representing race-to-race reproducibility of performance, were similar whether derived from finish rank or finish time for the time-trial events. Log-transformed finish ranks are therefore a suitable measure to assess and compare performance in time-trial and mass-start events. Omnium cyclists were more predictable in their performances from race to race in the timed events, whereas reduced predictability was observed in mass-start events. Interevent correlations indicated stronger links in performance between the timed disciplines, whereas performance in any of the mass-start events had only a slight positive relationship with performance in the other massstart events and little or no relationship with the timed events.

Conclusions:

Further investigation is warranted to determine whether factors related to performance in mass-start events can be identified to improve reproducibility or whether variability in performance results from random chance.

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Kenneth G. Holt, Suh Fang Jeng and Linda Fetters

Preferred stride frequency (PSF) of adult human walking has been shown to be predictable as the resonant frequency of a force driven harmonic oscillator (FDHO). The purpose of this study was to determine whether the PSF of 9-year-old children was predictable using the same resonance formula as that of adults. Subjects walked around a gymnasium at a rate at which they felt comfortable. Stride frequency was measured as the time for 20 strides and the stride period was calculated. The best-fit prediction based on resonance was then calculated using the overall center of mass of three segments (foot, shank, thigh) to determine the simple pendulum equivalent (SPE) length. Results indicated that a constant of 2 applied to the gravitational constant of the resonance formula, the same formulation used for adults, can be used to predict the cadence of children.

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Matt Spencer, Thomas Losnegard, Jostein Hallén and Will G. Hopkins

Analyses of elite competitive performance provide useful information for research and practical applications.

Purpose:

Here the authors analyze performance times of cross-country skiers at international competitions (World Cup, World Championship, and Olympics) in classical and free styles of women’s and men’s distance and sprint events, each with a total of 410–569 athletes competing in 1–44 races at 15–25 venues from seasons 2002 to 2011.

Methods:

A linear mixed model of race times for each event provided estimates of within-athlete race-to-race variability expressed as a coefficient of variation (CV) after adjustment for fixed or random effects of snow conditions, altitude, race length, and competition terrain.

Results:

Within-athlete variability was similar for men and women over various events for all athletes (CV of 1.5–1.8%) and for the annual top-10 athletes (1.1–1.4%). Observed effects of snow conditions and altitude on mean time were substantial (~2%) but mostly unclear, owing to large effects of terrain (CV of 4–10% in top-10 analyses). Predictability of performance was extremely high for all athletes (intraclass correlations of .90–.96) but only trivial to poor for top-10 athletes (men .00–.03, women .03–.35).

Conclusion:

The race-to-race variability of top-ranked skiers is similar to that of other elite endurance athletes. Estimates of the smallest worthwhile performance enhancement (0.3× within-athlete variability) will help researchers and practitioners evaluate strategies affecting performance of elite skiers.

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Tiago M. Barbosa, Wan Xiu Goh, Jorge E. Morais and Mário J. Costa

The aim was to examine the variation of linear and nonlinear proprieties of the behavior in participants with different levels of swimming expertise among the four swim strokes. Seventy-five swimmers were split into three groups (highly qualified experts, experts and nonexperts) and performed a maximal 25m trial for each of the four competitive swim strokes. A speed-meter cable was attached to the swimmer’s hip to measure hip speed; from which speed fluctuation (dv), approximate entropy (ApEn) and fractal dimension (D) variables were derived. Although simple main effects of expertise and swim stroke were obtained for dv and D, no significant interaction of expertise and stroke were found except in ApEn. The ApEn and D were prone to decrease with increasing expertise. As a conclusion, swimming does exhibit nonlinear properties but its magnitude differs according to the swim stroke and level of expertise of the performer.

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Dionne A. Noordhof, Roy C.M. Mulder, Jos J. de Koning and Will G. Hopkins

Analysis of sport performance can provide effects of environmental and other venue-specific factors in addition to estimates of within-athlete variability between competitions, which determines smallest worthwhile effects.

Purpose:

To analyze elite long-track speed-skating events.

Methods:

Log-transformed performance times were analyzed with a mixed linear model that estimated percentage mean effects for altitude, barometric pressure, type of rink, and competition importance. In addition, coefficients of variation representing residual venue-related differences and within-athlete variability between races within clusters spanning ~8 d were determined. Effects and variability were assessed with magnitude-based inference.

Results:

A 1000-m increase in altitude resulted in very large mean performance improvements of 2.8% in juniors and 2.1% in seniors. An increase in barometric pressure of 100 hPa resulted in a moderate reduction in performance of 1.1% for juniors but an unclear effect for seniors. Only juniors competed at open rinks, resulting in a very large reduction in performance of 3.4%. Juniors and seniors showed small performance improvements (0.4% and 0.3%) at the more important competitions. After accounting for these effects, residual venue-related variability was still moderate to large. The within-athlete within-cluster race-to-race variability was 0.3–1.3%, with a small difference in variability between male (0.8%) and female juniors (1.0%) and no difference between male and female seniors (both 0.6%).

Conclusion:

The variability in performance times of skaters is similar to that of athletes in other sports in which air or water resistance limits speed. A performance enhancement of 0.1–0.4% by top-10 athletes is necessary to increase medal-winning chances by 10%.

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Dylan C. Perry, Christopher C. Moore, Colleen J. Sands, Elroy J. Aguiar, Zachary R. Gould, Catrine Tudor-Locke and Scott W. Ducharme

neurological health-specific cadences corresponding to intensities that are recommended in PA guidelines. Implications and Future Directions This study demonstrates the utility of modulating a single commercial song to entrain cadence to elicit predictable changes in gait speed and metabolic cost. Considering

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Patrick Delisle-Houde, Nathan A. Chiarlitti, Ryan E.R. Reid and Ross E. Andersen

in the hockey milieu and performed at the NHL combine, and will therefore be included in the common laboratory/field-based category of this study. The purpose of this study was to determine the predictability of common laboratory/field and novel laboratory tests for skating characteristics in