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Samuel Sigrist, Thomas Maier and Raphael Faiss

enough in order to optimize race transitions is needed for an ideal performance. Practical Applications Interestingly, visual (and thus video) analysis certainly represents an adequate way to investigate a team pursuit race scheme. For instance, our results indicate a very low intrarater variability for

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Sakiko Oyama, Araceli Sosa, Rebekah Campbell and Alexandra Correa

Video recordings are used to quantitatively analyze pitchers’ techniques. However, reliability and validity of such analysis is unknown. The purpose of the study was to investigate the reliability and validity of joint and segment angles identified during a pitching motion using video analysis. Thirty high school baseball pitchers participated. The pitching motion was captured using 2 high-speed video cameras and a motion capture system. Two raters reviewed the videos to digitize the body segments to calculate 2-dimensional angles. The corresponding 3-dimensional angles were calculated from the motion capture data. Intrarater reliability, interrater reliability, and validity of the 2-dimensional angles were determined. The intrarater and interrater reliability of the 2-dimensional angles were high for most variables. The trunk contralateral flexion at maximum external rotation was the only variable with high validity. Trunk contralateral flexion at ball release, trunk forward flexion at foot contact and ball release, shoulder elevation angle at foot contact, and maximum shoulder external rotation had moderate validity. Two-dimensional angles at the shoulder, elbow, and trunk could be measured with high reliability. However, the angles are not necessarily anatomically correct, and thus use of quantitative video analysis should be limited to angles that can be measured with good validity.

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Maggi M. Calo, Thomas Anania, Joseph D. Bello, Valerie A. Cohen, Siobhan C. Stack, Meredith D. Wells, Barbara C. Belyea, Deborah L. King and Jennifer M. Medina McKeon

a screening tool to be used successfully to identify athletes at risk of LE injury, the tool must be reliable and simple to use by clinicians. Three-dimensional (3D) video analysis has long been considered the gold standard for analyzing the kinematics of an individual’s movement, with good to

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Annemarie M.H. de Witte, Monique A.M. Berger, Marco J.M. Hoozemans, Dirkjan H.E.J. Veeger and Lucas H.V. van der Woude

video analysis. Players were filmed and observed during one entire match using an approach previously described by de Witte et al. ( 2016 ). In brief, video footage was collected during four entire games in the Dutch first division competition and five games at the Easter Tournament of Wheelchair

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Barry S. Mason, Rienk M.A. van der Slikke, Michael J. Hutchinson, Monique A.M. Berger and Victoria L. Goosey-Tolfrey

Welmoed Sinnema and Daan Crombach for their assistance with the video analysis and to Loughborough University for facilitating the study. References 1. Coutts KD . Dynamics of wheelchair basketball . Med Sci Sports Exerc . 1992 ; 24 ( 2 ): 231 – 234 . PubMed ID: 1532225 doi:10

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Aaron T. Scanlan, Jordan L. Fox, Nattai R. Borges and Vincent J. Dalbo

Purpose:

Declines in high-intensity activity during game play (in-game approach) and performance tests measured pre- and postgame (across-game approach) have been used to assess player fatigue in basketball. However, a direct comparison of these approaches is not available. Consequently, this study examined the commonality between in- and across-game jump fatigue during simulated basketball game play.

Methods:

Australian, state-level, junior male basketball players (n = 10; 16.6 ± 1.1 y, 182.4 ± 4.3 cm, 68.3 ± 10.2 kg) completed 4 × 10-min standardized quarters of simulated basketball game play. In-game jump height during game play was measured using video analysis, while across-game jump height was determined pre-, mid-, and postgame play using an in-ground force platform. Jump height was determined using the flight-time method, with jump decrement calculated for each approach across the first half, second half, and entire game.

Results:

A greater jump decrement was apparent for the in-game approach than for the across-game approach in the first half (37.1% ± 11.6% vs 1.7% ± 6.2%; P = .005; d = 3.81, large), while nonsignificant, large differences were evident between approaches in the second half (d = 1.14) and entire game (d = 1.83). Nonsignificant associations were evident between in-game and across-game jump decrement, with shared variances of 3–26%.

Conclusions:

Large differences and a low commonality were observed between in- and across-game jump fatigue during basketball game play, suggesting that these approaches measure different constructs. Based on our findings, it is not recommended that basketball coaches use these approaches interchangeably to monitor player fatigue across the season.

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Edward J. Bradley, Bob Hogg and David T. Archer

This study examined whether changes in scrum engagement laws from the “crouch-touch-set” in 2013 to the “PreBind” engagement from 2014 onward have led to changes in scrum characteristics, specifically timing, in international rugby union. Duration and outcomes were identified for all scrums occurring in the 2013–16 Six Nations (N = 60 games) using video analysis. Scrum duration increased after the introduction of the PreBind engagement from 59 s in 2013 to 69 s in 2016 (P = .024, effect size = 0.93). A significant increase in mean contact duration per scrum occurred when prebinding was adopted (P < .05), moving from 7.5 s under the crouch-touch-set process to 8.5, 10.0, and 10.8 s with PreBind in 2014, 2015, and 2016 (effect size = 0.71, 2.05, and 3.0, respectively). The number of scrum resets and collapsed scrums, along with early engagement and pulling down infringements, was lower under the PreBind process. Overall, the PreBind engagement resulted in longer scrums with significant increases observed in overall and contact durations, with improved stability-related characteristics. The longer contact time is a consequence of increased stability with a shift from high-energy impact to a sustained push phase with a lower force that is a benefit to player welfare.

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Philip Davis, Peter R. Benson, James D. Pitty, Andrew J. Connorton and Robert Waldock

An activity profile of competitive 3 × 3-min elite-level amateur boxing was created from video footage of 29 Olympic final and semifinal bouts in 39 male boxers (mean ± SD) age 25.1 ± 3.6 y, height 178.3 ± 10.4 cm, and body mass 69.7 ± 16.5 kg. Boxing at this level requires the ability to maintain an activity rate of ~1.4 actions/s, consisting of ~20 punches, ~2.5 defensive movements, and ~47 vertical hip movements, all per minute, over 3 subsequent rounds lasting ~200 s each. Winners had higher total punches landed (P = .041) and a lower ratio of punches thrown to landed (P = .027) than losers in round 3. The hook rearhand landed was also higher for winners than losers in round 2 (P = .038) and round 3 (P = .016), and defensive movements were used less by winners (P = .036). However, the results suggest that technical discrimination between winners and losers is difficult; bout outcome may be more dependent on which punch is “lucky” enough to be scored by the judges or who appears to be dominant on the day. This study gives both boxers and coaches a good idea of where subelite boxers need to aim if they want to become among the best amateur boxers in the world.

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Philip Davis, Peter R. Benson, Robert Waldock and Andrew J. Connorton

Female boxing debuted at the 2012 London Olympic Games. To better understand the performance aspects of the sport, video footage of eighteen 4 × 2-min bouts were analyzed. The boxers involved in the competition were of an elite level (mean ± SD), age 26.4 ± 4.6 y, height 169.3 ± 6.2 cm, and weight 60.3 ± 10.0 kg. Analysis revealed an activity rate of ~1.6 actions/s, including ~16 punches, ~3.3 defensive movements, and ~63 vertical hip movements, all per minute, over the 4 × ~132-s rounds (R). A 2 × 4 (outcome × round) ANOVA with repeated measures over the rounds was used to analyze the data. Winners maintained a higher activity rate in round 1 (R1) and R2; a higher movement rate in R2, R3, and R4; and an increased punch accuracy including the ratio of total punches to punches landed in R3 and air punches as a percentage of punches missed in R1 and R3. Specific techniques that discriminate between successful and unsuccessful female amateur boxers include the straight rear-hand and body punches, higher for winners in R1, as well as uppercut punches and defensive foot movements, higher for winners in R4. Findings highlight the current demands of elite amateur female boxing. These data will be useful for those designing training programs and may also be useful for guiding sport-specific fitness testing.

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Aurel Coza, Benno M. Nigg and Ladina Fliri

Soft-tissue vibrations can be used to quantify selected properties of human tissue and their response to impact. Vibrations are typically quantified using high-speed motion capture or accelerometry. The aim of this study was to compare the amplitude and frequency of soft-tissue vibrations during running when quantified by highspeed motion capture and accelerometry simultaneously. This study showed: (a) The estimated measurement errors for amplitude and frequency were of the same order of magnitude for both techniques. (b) There were no significant differences in the mean peak frequencies and peak amplitudes measured by the two methods. (c) The video method showed an inability to capture high frequency information. This study has shown that a tradeoff has to be made between the accuracy in amplitude and frequency when these methods are employed to quantify soft tissue vibrations in running.