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Nick B. Murray, Tim J. Gabbett and Andrew D. Townshend

Objectives:

To investigate the relationship between the proportion of preseason training sessions completed and load and injury during the ensuing Australian Football League season.

Design:

Single-cohort, observational study.

Methods:

Forty-six elite male Australian football players from 1 club participated. Players were divided into 3 equal groups based on the amount of preseason training completed (high [HTL], >85% sessions completed; medium [MTL], 50–85% sessions completed; and low [LTL], <50% sessions completed). Global positioning system (GPS) technology was used to record training and game loads, with all injuries recorded and classified by club medical staff. Differences between groups were analyzed using a 2-way (group × training/competition phase) repeated-measures ANOVA, along with magnitude-based inferences. Injury incidence was expressed as injuries per 1000 h.

Results:

The HTL and MTL groups completed a greater proportion of in-season training sessions (81.1% and 74.2%) and matches (76.7% and 76.1%) than the LTL (56.9% and 52.7%) group. Total distance and player load were significantly greater during the first half of the in-season period for the HTL (P = .03, ES = 0.88) and MTL (P = .02, ES = 0.93) groups than the LTL group. The relative risk of injury for the LTL group (26.8/1000 h) was 1.9 times greater than that for the HTL group (14.2/1000 h) (χ2 = 3.48, df = 2, P = .17).

Conclusions:

Completing a greater proportion of preseason training resulted in higher training loads and greater participation in training and competition during the competitive phase of the season.

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Dac Minh Tuan Nguyen, Virgile Lecoultre, Yoshiyuki Sunami and Yves Schutz

Background:

Physical activity (PA) and related energy expenditure (EE) is often assessed by means of a single technique. Because of inherent limitations, single techniques may not allow for an accurate assessment both PA and related EE. The aim of this study was to develop a model to accurately assess common PA types and durations and thus EE in free-living conditions, combining data from global positioning system (GPS) and 2 accelerometers.

Methods:

Forty-one volunteers participated in the study. First, a model was developed and adjusted to measured EE with a first group of subjects (Protocol I, n = 12) who performed 6 structured and supervised PA. Then, the model was validated over 2 experimental phases with 2 groups (n = 12 and n = 17) performing scheduled (Protocol I) and spontaneous common activities in real-life condition (Protocol II). Predicted EE was compared with actual EE as measured by portable indirect calorimetry.

Results:

In protocol I, performed PA types could be recognized with little error. The duration of each PA type could be predicted with an accuracy below 1 minute. Measured and predicted EE were strongly associated (r = .97, P < .001).

Conclusion:

Combining GPS and 2 accelerometers allows for an accurate assessment of PA and EE in free-living situations.

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Mohamed S. Fessi, Fayçal Farhat, Alexandre Dellal, James J. Malone and Wassim Moalla

matches. 10 , 11 Common methods include time–motion analysis (such as video 11 and global positioning systems [GPS]), 12 – 14 heart-rate kinetics, 10 , 15 and rating of perceived exertion (RPE). 10 , 16 Usually, GPS technology is used to measure the distance covered or time spent at different running

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Nick B. Murray, Tim J. Gabbett and Andrew D. Townshend

use Global Positioning System (GPS) technology to provide information on the activity profiles of players during training and compeition. 3 – 5 With the physical demands of AF increasing, 6 it is critical that strength and conditioning staff prescribe an appropriate training stimulus to enhance the

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Gregory Roe, Joshua Darrall-Jones, Christopher Black, William Shaw, Kevin Till and Ben Jones

Purpose:

The purpose of this study was to investigate the validity of timing gates and 10-Hz global positioning systems (GPS) units (Catapult Optimeye S5) against a criterion measure (50-Hz radar gun) for assessing maximum sprint velocity (Vmax).

Methods:

Nine male professional rugby union players performed 3 maximal 40-m sprints with 3 min rest between efforts with Vmax assessed simultaneously via timing gates, 10-Hz GPSOpen (Openfield software), GPSSprint (Sprint software), and radar gun. Eight players wore 3 GPS units, while 1 wore a single unit during each sprint.

Results:

When compared with the radar gun, mean biases for GPSOpen, GPSSprint, and timing gates were trivial, small, and small, respectively. The typical error of the estimate (TEE) was small for timing gate and GPSOpen while moderate for GPSSprint. Correlations with radar gun were nearly perfect for all measures. Mean bias, TEE, and correlations between GPS units were trivial, small, and nearly perfect, respectively, while a small TEE existed when GPSOpenfield was compared with GPSSprint.

Conclusion:

Based on these findings, both 10-Hz GPS and timing gates provide valid measures of 40-m Vmax assessment compared with a radar gun. However, as error did exist between measures, the same testing protocol should be used when assessing 40-m Vmax over time. Furthermore, in light of the above results, it is recommended that when assessing changes in GPS-derived Vmax over time, practitioners should use the same unit for each player and perform the analysis with the same software, preferably Catapult Openfield.

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Joel Garrett, Stuart R. Graham, Roger G. Eston, Darren J. Burgess, Lachlan J. Garrett, John Jakeman and Kevin Norton

25-m halfway mark to help control for speed of the run. Average performance across the 3 trials was used as the criterion measure. The GPS-embedded triaxial accelerometers unit was worn in a specialized pocket in the training and match guernsey, located between the scapulae of the participant. For

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Esther Morencos, Blanca Romero-Moraleda, Carlo Castagna and David Casamichana

In recent years, global positioning system (GPS) analysis has become a widely used tool for quantifying competition demands, informing training prescription, and monitoring the training stimulus. 1 In team sports such as hockey, considered as intermittent, high-intensity activity, 2 reductions in

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Fergus O’Connor, Heidi R. Thornton, Dean Ritchie, Jay Anderson, Lindsay Bull, Alex Rigby, Zane Leonard, Steven Stern and Jonathan D. Bartlett

also represent a significant risk of soft-tissue injury, particularly if the athlete is not conditioned to undergo maximal sprinting early in the preseason. Developments in commercially available global positioning systems (GPS) allow practitioners to reliably measure maximal velocity when it occurs

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Jonathon J.S. Weakley, Dale B. Read, Hugh H.K. Fullagar, Carlos Ramirez-Lopez, Ben Jones, Cloe Cummins and John A. Sampson

end of each bout) during SSGs has not been assessed. Team sport athletes often wear microtechnology devices that contain a global positioning system (GPS) and inertial sensors during training and match play. 15 – 17 These devices are commonly used to monitor training loads and intensities, with

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Cesar Gallo-Salazar, Juan Del Coso, David Sanz-Rivas and Jaime Fernandez-Fernandez

-Eye, 5 or global position systems (GPS) 6 – 11 among the most typically used for these purposes. Quantifying this information during real or simulated tennis matches helps coaches to provide objective knowledge about the demands of match play, ultimately improving the preparation of more effective