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Pedro Figueiredo, George P. Nassis and João Brito

perceived exertion (s-RPE). Players also used 10-Hz global positioning system (GPS) pods during training sessions (Viper Pod; STATSports, Newry, Northern Ireland). External load variables included total training time, total distance covered, distance covered per minute, high-speed distance (>14.4 km

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Liam Anderson, Graeme L. Close, Ryland Morgans, Catherine Hambly, John Roger Speakman, Barry Drust and James P. Morton

contractions etc) that are not often considered when using global positioning system (GPS) data to make inferences of daily EE. Methods Overview of the Player The player is a 27-year old male professional GK (body mass 85.6 kg, height 191 cm from a headless scan, percentage body fat 11.9%, fat mass 9.8 kg

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Jeroen de Bruijn, Henk van der Worp, Mark Korte, Astrid de Vries, Rick Nijland and Michel Brink

Corporation, Annapolis, MD, US). This system consists of a chest strap, a data module, GPS-trackers, and a laptop including Zephyr ™ software. The chest strap has the ability to measure heart rate due to 2 electrocardiogram (ECG) sensors and the GPS trackers can be easily attached to the chest strap using an

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Tannath J. Scott, Heidi R. Thornton, Macfarlane T.U. Scott, Ben J. Dascombe and Grant M. Duthie

Advancements in technology have led to the extensive implementation of global positioning systems (GPS) and microtechnology in team sports to quantify movement demands. The ability to more reliably quantify and interpret these demands has led to a greater understanding of the external loads

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Heidi R. Thornton, Jace A. Delaney, Grant M. Duthie and Ben J. Dascombe

sessions and matches were quantified using GPS units at a sampling rate of 5 Hz, interpolated to 15 Hz (SPI HPU, GPSports, Canberra, Australia). These were placed in a custom-made pouch in a vest positioned between the scapulae of the upper back. These units are deemed valid and reliable for quantifying

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Darcy M. Brown, Dan B. Dwyer, Samuel J. Robertson and Paul B. Gastin

The purpose of this study was to assess the validity of a global positioning system (GPS) tracking system to estimate energy expenditure (EE) during exercise and field-sport locomotor movements. Twenty-seven participants each completed a 90-min exercise session on an outdoor synthetic futsal pitch. During the exercise session, they wore a 5-Hz GPS unit interpolated to 15 Hz and a portable gas analyzer that acted as the criterion measure of EE. The exercise session was composed of alternating 5-minute exercise bouts of randomized walking, jogging, running, or a field-sport circuit (×3) followed by 10 min of recovery. One-way analysis of variance showed significant (P < .01) and very large underestimations between GPS metabolic power– derived EE and oxygen-consumption (VO2) -derived EE for all field-sport circuits (% difference ≈ –44%). No differences in EE were observed for the jog (7.8%) and run (4.8%), whereas very large overestimations were found for the walk (43.0%). The GPS metabolic power EE over the entire 90-min session was significantly lower (P < .01) than the VO2 EE, resulting in a moderate underestimation overall (–19%). The results of this study suggest that a GPS tracking system using the metabolic power model of EE does not accurately estimate EE in field-sport movements or over an exercise session consisting of mixed locomotor activities interspersed with recovery periods; however, is it able to provide a reasonably accurate estimation of EE during continuous jogging and running.

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Grégoire P. Millet and Kilian Jornet

98%, and the subject reported regularly “dizziness symptoms.” The training volumes/contents as well as the duration of NH or HH exposures were calculated from his training diary. The times and uphill velocities were calculated from his GPS online data. Results The details of the activity (running

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Matt Greig and Philip Nagy

Context:

Epidemiological studies highlight a prevalence of lumbar vertebrae injuries in cricket fast bowlers, with governing bodies implementing rules to reduce exposure. Analysis typically requires complex and laboratory-based biomechanical analyses, lacking ecological validity. Developments in GPS microtechnologies facilitate on-field measures of mechanical intensity, facilitating screening toward prevention and rehabilitation.

Objective:

To examine the efficacy of using GPS-mounted triaxial accelerometers to quantify accumulated body load and to investigate the effect of GPS-unit placement in relation to epidemiological observations.

Design:

Repeated measures, field-based.

Setting:

Regulation cricket pitch.

Participants:

10 male injury-free participants recruited from a cricket academy (18.1 ± 0.6 y).

Intervention:

Each participant was fitted with 2 GPS units placed at the cervicothoracic and lumbar spines to measure triaxial acceleration (100 Hz). Participants were instructed to deliver a 7-over spell of fast bowling, as dictated by governing-body guidelines.

Main Outcome Measures:

Triaxial total accumulated body and the relative uniaxial contributions were calculated for each over.

Results:

There was no significant main effect for overs bowled, in either total load or the triaxial contributions to total load. This finding suggests no cumulative fatigue effect across the 10-over spell. However, there was a significant main effect for GPS-unit location, with the lumbar unit exposed to significantly greater load than the cervicothoracic unit in each of the triaxial planes.

Conclusions:

There was no evidence to suggest that accumulated load significantly increased as a result of spell duration. In this respect the governing-body guidelines for this age group can be considered safe, or potentially even conservative. However, the observation of higher body load at the lumbar spine than at the cervicothoracic spine supports epidemiological observations of injury incidence. GPS microtechnologies might therefore be considered in screening and monitoring of players toward injury prevention and/or during rehabilitation.

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Ralph Maddison, Yannan Jiang, Stephen Vander Hoorn, Daniel Exeter, Cliona Ni Mhurchu and Enid Dorey

This study aimed to describe the location and intensity of free-living physical activity in New Zealand adolescents during weekdays and weekend days using Global Positioning Systems (GPS), accelerometry, and Geographical Information Systems (GIS). Participants (n = 79) aged 12–17 years (M = 14.5, SD 1.6) recruited from two large metropolitan high schools each wore a GPS watch and an accelerometer for four consecutive days. GPS and accelerometer data were integrated with GIS software to map the main locations of each participant’s episodes of moderate-vigorous physical activity. On average participants performed 74 (SD 36) minutes of moderate and 7.5 (SD 8) minutes of vigorous activity per day, which on weekdays was most likely to occur within a 1 km radius of their school or 150 meters of their home environment. On weekends physical activity patterns were more disparate and took place outside of the home environment. Example maps were generated to display the location of moderate to vigorous activity for weekdays and weekends.

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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.