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Benjamin M. Jackson, Ted Polglaze, Brian Dawson, Trish King and Peter Peeling

In team sports, rapid changes in speed and direction are common, however changes in direction have been found to reduce the accuracy of GPS-derived distance measures, 13 and accelerations >4 m·s −2 have been found to reduce the reliability of GPS-derived speed measures. 14 Consequently, important

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Logan A. Lucas, Benjamin S. England, Travis W. Mason, Christopher R. Lanning, Taylor M. Miller, Alexander M. Morgan and Thomas Gus Almonroeder

3 times an athlete’s body weight. 7 These impact forces generate a transient spike in acceleration which is transmitted throughout the musculoskeletal system from the foot to the head. 8 Although the lower-extremity musculature can help to attenuate these impact accelerations, passive tissues also

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Kevin G. Aubol, Jillian L. Hawkins and Clare E. Milner

Tibial acceleration is thought to be related to overuse running injuries, particularly tibial stress fractures. 1 , 2 Peak axial tibial acceleration and peak resultant tibial acceleration are common outcome measures in studies of running. These measurements must be reliable so that the

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David S. Haydon, Ross A. Pinder, Paul N. Grimshaw and William S.P. Robertson

classifications, 1 as well as performance outcomes. 2 Despite an increase in popularity and research in wheelchair rugby (WCR), there is currently a limited understanding of how the level of activity limitation affects key kinematic variables and their impact on chair acceleration and sprint performance

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César Meylan, Joshua Trewin and Kelly McKean

The aims of the current study were to examine the external validity of inertial-based parameters (inertial movement analysis [IMA]) to detect multiplanar explosive actions during maximal sprinting and change of direction (COD) and to further determine its reliability, set appropriate magnitude bands for match analysis, and assess its variability during international women’s soccer matches. Twenty U20 female soccer players, wearing global positioning system (GPS) units with a built-in accelerometer, completed 3 trials of a 40-m sprint and a 20-m sprint with a change of direction to the right or left at 10 m. Furthermore, 13 women’s national-team players (157 files; 4–27 matches/player) were analyzed to ascertain match-to-match variability. Video synchronization indicated that the IMA signal was instantaneous with explosive movement (acceleration, deceleration, COD). Peak GPS velocity during the 40-m sprint showed similar reliability (coefficient of variation [CV] = 2.1%) to timing gates but increased before and after COD (CV = 4.5–13%). IMA variability was greater at the start of sprints (CV = 16–21%) than before and after COD (CV = 13–16%). IMA threshold for match analysis was set at 2.5 m · s–1 · s–1 by subtracting 1 SD from the mean IMA during sprint trials. IMA match variability (CV = 14%) differed from high-speed GPS metrics (35–60%). Practitioners are advised that timing lights should remain the gold standard for monitoring sprint and acceleration capabilities of athletes. However, IMA could be a reliable method to monitor explosive actions between matches and assess changes due to various factors such as congested schedule, tactics, heat, or altitude.

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Claire J. Brady, Andrew J. Harrison, Eamonn P. Flanagan, G. Gregory Haff and Thomas M. Comyns

Successful performance in sprint events requires rapid acceleration and a high maximum velocity. The starting-block phase and the subsequent acceleration phase are 2 important phases of sprint events, shown to directly generate results in a 60- and 100-m sprints. 1 During the acceleration phase

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Oren Tirosh, Guy Orland, Alon Eliakim, Dan Nemet and Nili Steinberg

stride length and moderately with stride frequency. 3 These findings are expected because tibia peak positive acceleration was found to increase with speed 3 , 4 while the body was found to respond to varying impact situations and sufficiently attenuate the impact shock to maintain constant head

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Ryu Nagahara, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa and Tetsuo Fukunaga

preceding acceleration. In contrast, Morin et al 6 and Rabita et al 8 found no significant relationship between averaged vertical force or impulse over a 40-m distance and either maximal speed or mean running speed over 40 m. They demonstrated that a larger propulsive force or impulse during the

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Lydia R. Vollavanh, Kathleen M. O’Day, Elizabeth M. Koehling, James M. May, Katherine M. Breedlove, Evan L. Breedlove, Eric A. Nauman, Debbie A. Bradney, J. Eric Goff and Thomas G. Bowman

rotational accelerations based on player position, event type, and location of impact in football. 7 , 16 Researchers also noted differences in mechanism, event type, and location of impact in youth and collegiate ice hockey. 4 , 14 To date, research into head impacts in men’s lacrosse is limited. 25 The

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Adriana M. Duquette and David M. Andrews

Considerable variability in tibial acceleration slope (AS) values, and different interpretations of injury risk based on these values, have been reported. Acceleration slope variability may be due in part to variations in the quantification methods used. Therefore, the purpose of this study was to quantify differences in tibial AS values determined using end points at various percentage ranges between impact and peak tibial acceleration, as a function of either amplitude or time. Tibial accelerations were recorded from 20 participants (21.8 ± 2.9 years, 1.7 m ± 0.1 m, 75.1 kg ± 17.0 kg) during 24 unshod heel impacts using a human pendulum apparatus. Nine ranges were tested from 5–95% (widest range) to 45–55% (narrowest range) at 5% increments. ASAmplitude values increased consistently from the widest to narrowest ranges, whereas the ASTime values remained essentially the same. The magnitudes of ASAmplitude values were significantly higher and more sensitive to changes in percentage range than ASTime values derived from the same impact data. This study shows that tibial AS magnitudes are highly dependent on the method used to calculate them. Researchers are encouraged to carefully consider the method they use to calculate AS so that equivalent comparisons and assessments of injury risk across studies can be made.