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Denise Jennings, Stuart Cormack, Aaron J. Coutts, Luke Boyd and Robert J. Aughey

Purpose:

To assess the validity and reliability of distance data measured by global positioning system (GPS) units sampling at 1 and 5 Hz during movement patterns common to team sports.

Methods:

Twenty elite Australian Football players each wearing two GPS devices (MinimaxX, Catapult, Australia) completed straight line movements (10, 20, 40 m) at various speeds (walk, jog, stride, sprint), changes of direction (COD) courses of two different frequencies (gradual and tight), and a team sport running simulation circuit. Position and speed data were collected by the GPS devices at 1 and 5 Hz. Distance validity was assessed using the standard error of the estimate (±90% confidence intervals [CI]). Reliability was estimated using typical error (TE) ± 90% CI (expressed as coefficient of variation [CV]).

Results:

Measurement accuracy decreased as speed of locomotion increased in both straight line and the COD courses. Difference between criterion and GPS measured distance ranged from 9.0% to 32.4%. A higher sampling rate improved validity regardless of distance and locomotion in the straight line, COD and simulated running circuit trials. The reliability improved as distance traveled increased but decreased as speed increased. Total distance over the simulated running circuit exhibited the lowest variation (CV 3.6%) while sprinting over 10 m demonstrated the highest (CV 77.2% at 1 Hz).

Conclusion:

Current GPS systems maybe limited for assessment of short, high speed straight line running and efforts involving change of direction. An increased sample rate improves validity and reliability of GPS devices.

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Ryu Nagahara, Alberto Botter, Enrico Rejc, Masaaki Koido, Takeshi Shimizu, Pierre Samozino and Jean-Benoit Morin

Purpose:

To test the concurrent validity of data from 2 different global positioning system (GPS) units for obtaining mechanical properties during sprint acceleration using a field method recently validated by Samozino et al.

Methods:

Thirty-two athletes performed maximal straight-line sprints, and their running speed was simultaneously measured by GPS units (sampling rate: 20 or 5 Hz) and either a radar or laser device (devices taken as references). Lower-limb mechanical properties of sprint acceleration (theoretical maximal force, theoretical maximal speed, maximal power) were derived from a modeling of the speed–time curves using an exponential function in both measurements. Comparisons of mechanical properties from 20- and 5-Hz GPS units with those from reference devices were performed for 80 and 62 trials, respectively.

Results:

The percentage bias showed a wide range of overestimation or underestimation for both systems (-7.9% to 9.7% and -5.1% to 2.9% for 20- and 5-Hz GPS), while the ranges of its 90% confidence limits for 20-Hz GPS were markedly smaller than those for 5-Hz GPS. These results were supported by the correlation analyses.

Conclusions:

Overall, the concurrent validity for all variables derived from 20-Hz GPS measurements was better than that obtained from the 5-Hz GPS units. However, in the current state of GPS devices’ accuracy for speed–time measurements over a maximal sprint acceleration, it is recommended that radar, laser devices, and timing gates remain the reference methods for implementing the computations of Samozino et al.

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Denise Jennings, Stuart J. Cormack, Aaron J. Coutts and Robert J. Aughey

Purpose:

The purpose of this study was to investigate the influence of multiple games on exercise intensity during a world-class hockey tournament.

Methods:

15 players (mean ± SD age 27 ± 4 y, stature 179 ± 5 cm, body mass 77 ± 5 kg, and estimated VO2 64.2 ± 3.1 mL · kg−1 · min−1) competing in the Champions Trophy (CT). Global-positioning systems assessed total distance (TD), low-speed activity (LSA; 0.10–4.17 m/s), and high-speed running (HSR; >4.17 m/s) distance. Differences in movement demands (TD, LSA, HSR) between positions and matches were assessed using the effect size and percent difference ± 90% confidence intervals. Two levels of comparison were made. First, data from subsequent matches were compared with match 1, and, second, data from each match compared with a tournament average (TA).

Results:

In all matches, compared with game 1, midfielders performed less HSR distance. However, the amount of HSR did not decrease as the tournament progressed. When compared with the TA, defenders showed more variation in each match. All positions showed lower movement outputs when the team won by a large margin.

Conclusions:

It was possible for elite team-sport athletes to maintain exercise intensity when playing 6 matches in a period of 9 days, contrary to the only other investigation of this in elite male field hockey.

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Andrew D. White and Niall MacFarlane

Purpose:

The current study assessed the impact of full-game (FG) and time-on-pitch (TOP) procedures for global-positioning-system (GPS) analysis on the commonly used markers of physical performance in elite field hockey.

Methods:

Sixteen international male field hockey players, age 19–30, were studied (yielding 73 player analyses over 8 games). Physical activity was recorded using a 5-Hz GPS.

Results:

Distance covered, player load, maximum velocity, high-acceleration efforts, and distance covered at specified speed zones were all agreeable for both analysis procedures (P > .05). However, percentage time spent in 0–6 km/h was higher for FG (ES: –21% to –16%; P < .001), whereas the percentage time in all other speed zones (1.67–3.06 m/s, 3.06–4.17 m/s, 4.17–5.28 m/s, and > 6.39 m/s) and relative distance (m/min) were higher for TOP (ES: 8–10%, 2–7%, 2–3%, 1–1%, 0–1%, respectively; P < .001).

Conclusions:

These data demonstrate that GPS analysis procedures should be appropriate for the nature of the sport being studied. In field hockey, TOP and FG analysis procedures are comparable for distance-related variables but significantly different for time-dependent factors. Using inappropriate analysis procedures can alter the perceived physiological demand of elite field hockey because of “rolling” substitutions. Inaccurate perception of physiological demand could negatively influence training prescription (for both intensity and volume).

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Luis Suarez-Arrones, Javier Núñez, Eduardo Sáez de Villareal, Javier Gálvez, Gabriel Suarez-Sanchez and Diego Munguía-Izquierdo

Purpose:

To describe the repeated-high-intensity activity and internal training load of rugby sevens players during international matches and to compare the differences between the 1st and 2nd halves.

Methods:

Twelve international-level male rugby sevens players were monitored during international competitive matches (n = 30 match files) using global positioning system technology and heart-rate monitoring.

Results:

The relative total distance covered by the players throughout the match was 112.1 ± 8.4 m/min. As a percentage of total distance, 35.0% (39.2 ± 9.0 m/min) was covered at medium speed and 17.1% (19.2 ± 6.8 m/min) at high speed. A substantial decrease in the distance covered at >14.0 km/h and >18.0 km/h, the number of accelerations of >2.78 m/s and >4.0 m/s, repeated-sprint sequences interspersed with ≤60 s rest, and repeated-acceleration sequences interspersed with ≤30 s or ≤60 s rest was observed in the 2nd half compared with the 1st half. A substantial increase in the mean heart rate (HR), HRmax, percentage of time at >80% HRmax and at >90% HRmax, and Edwards training load was observed in the 2nd half compared with the 1st half.

Conclusion:

This study provides evidence of a pronounced reduction in high-intensity and repeated-highintensity activities and increases in internal training load in rugby sevens players during the 2nd half of international matches.

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Rich D. Johnston, Tim J. Gabbett and David G. Jenkins

Purpose:

To assess the influence of playing standard and physical fitness on pacing strategies during a junior team-sport tournament.

Methods:

A between-groups, repeated-measures design was used. Twenty-eight junior team-sport players (age 16.6 ± 0.5 y, body mass 79.9 ± 12.0 kg) from a high-standard and low-standard team participated in a junior rugby league tournament, competing in 5 games over 4 d (4 × 40-min and 1 × 50-min game). Players wore global positioning system (GPS) microtechnology during each game to provide information on match activity profiles. The Yo-Yo Intermittent Recovery Test (level 1) was used to assess physical fitness before the competition.

Results:

High-standard players had an initially higher pacing strategy than the low-standard players, covering greater distances at high (ES = 1.32) and moderate speed (ES = 1.41) in game 1 and moderate speed (ES = 1.55) in game 2. However, low-standard players increased their playing intensity across the competition (ES = 0.57–2.04). High-standard/high-fitness players maintained a similar playing intensity, whereas high-standard/low-fitness players reduced their playing intensities across the competition.

Conclusions:

Well-developed physical fitness allows for a higher-intensity pacing strategy that can be maintained throughout a tournament. High-standard/low-fitness players reduce playing intensity, most likely due to increased levels of fatigue as the competition progresses. Low-standard players adopt a pacing strategy that allows them to conserve energy to produce an “end spurt” in the latter games. Maximizing endurance fitness across an entire playing group will maximize playing intensity and minimize performance reductions during the latter stages of a tournament.

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Georgia M. Black and Tim J. Gabbett

Purpose:

No study has investigated the frequency and nature of repeated high-intensity-effort (RHIE) bouts across elite and semielite rugby league competitions. This study examined RHIE activity in rugby league match play across playing standards.

Participants:

36 elite and 64 semielite rugby league players.

Methods:

Global positioning system analysis was completed during 17 elite and 14 semielite matches.

Results:

The most commonly occurring RHIE bouts involved 2 efforts (2-RHIE) for both elite and semielite players. Only small differences were found in 2-RHIE activity between elite and semielite match play (effect size [ES] ≥0.31 ± 0.15, ≥88%, likely). RHIE bouts were more likely to involve contact as the number of efforts in a bout increased (ES ≥0.40 ± 0.15, 100%, almost certainly). Semielite players performed a greater proportion of 2-contact-effort RHIE bouts than their elite counterparts (68.2% vs 60.6%, ES 0.33 ± 0.15, 92%, likely), while elite players performed a greater proportion of 3-effort bouts (26.9% vs 21.1%, ES 0.31 ± 0.15, 88%, likely). Elite players also had a shorter recovery (1.00−3.99 vs ≥4.00 min) between RHIE bouts (ES ≥1.60 ± 0.71, ≥94%, likely).

Conclusion:

These findings highlight the RHIE demands of elite and semielite rugby league match play. Elite players are more likely to perform RHIE bouts consisting of 3 efforts and to have a shorter recovery time between bouts. Exposing players to these RHIE demands in training is likely to improve their ability to tolerate the most demanding passages of match play.

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Rich D. Johnston, Tim J. Gabbett and David G. Jenkins

Purpose:

To determine the influence the number of contact efforts during a single bout has on running intensity during game-based activities and assess relationships between physical qualities and distances covered in each game.

Methods:

Eighteen semiprofessional rugby league players (age 23.6 ± 2.8 y) competed in 3 off-side small-sided games (2 × 10-min halves) with a contact bout performed every 2 min. The rules of each game were identical except for the number of contact efforts performed in each bout. Players performed 1, 2, or 3 × 5-s wrestles in the single-, double-, and triple-contact game, respectively. The movement demands (including distance covered and intensity of exercise) in each game were monitored using global positioning system units. Bench-press and back-squat 1-repetition maximum and the 30−15 Intermittent Fitness Test (30−15IFT) assessed muscle strength and high-intensity-running ability, respectively.

Results:

There was little change in distance covered during the single-contact game (ES = −0.16 to −0.61), whereas there were larger reductions in the double- (ES = −0.52 to −0.81) and triple-contact (ES = −0.50 to −1.15) games. Significant relationships (P < .05) were observed between 30–15IFT and high-speed running during the single- (r = .72) and double- (r = .75), but not triple-contact (r = .20) game.

Conclusions:

There is little change in running intensity when only single contacts are performed each bout; however, when multiple contacts are performed, greater reductions in running intensity result. In addition, high-intensity-running ability is only associated with running performance when contact demands are low.

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Laura A. Garvican, Kristal Hammond, Matthew C. Varley, Christopher J. Gore, Francois Billaut and Robert J. Aughey

Purpose:

This study investigated the decrement in running performance of elite soccer players competing at low altitude and time course for abatement of these decrements.

Methods:

Twenty elite youth soccer players had their activity profile, in a sea-level (SL) and 2 altitude (Alt, 1600 m, d 4, and d 6) matches, measured with a global positioning system. Measures expressed in meters per minute of match time were total distance, low- and high-velocity running (LoVR, 0.01–4.16 m/s; HiVR, 4.17–10.0 m/s), and frequency of maximal accelerations (>2.78 m/s2). The peak and subsequent stanza for each measure were identified and a transient fatigue index calculated. Mean heart rate (HR) during the final minute of a submaximal running task (5 min, 11 km/h) was recorded at SL and for 10 d at Alt. Differences were determined between SL and Alt using percentage change and effect-size (ES) statistic with 90% confidence intervals.

Results:

Mean HR almost certainly increased on d 1 (5.4%, ES 1.01 ± 0.35) and remained probably elevated on both d 2 (ES 0.42 ± 0.31) and d3 (ES 0.30 ± 0.25), returning to baseline at d 5. Total distance was almost certainly lower than SL (ES –0.76 ± 0.37) at d 4 and remained probably reduced on d 6 (ES –0.42 ± 0.36). HiVR probably decreased at d 4 vs SL (–0.47 ± 0.59), with no clear effect of altitude at d 6 (–0.08 ± 0.41). Transient fatigue in matches was evident at SL and Alt, with a possibly greater decrement at Alt.

Conclusion:

Despite some physiological adaptation, match running performance of youth soccer players is compromised for at least 6 d at low altitude.

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Tim J. Gabbett

Purpose:

A limitation of most rugby league time–motion studies is that researchers have examined the demands of single teams, with no investigations of all teams in an entire competition. This study investigated the activity profiles and technical and tactical performances of successful and less-successful teams throughout an entire rugby league competition.

Methods:

In total, 185 rugby league players representing 11 teams from a semiprofessional competition participated in this study. Global positioning system analysis was completed across the entire season. Video footage from individual matches was also coded via notational analysis for technical and tactical performance of teams.

Results:

Trivial to small differences were found among Top 4, Middle 4, and Bottom 4 teams for absolute and relative total distances covered and distances covered at low speeds. Small, nonsignificant differences (P = .054, ES = 0.31) were found between groups for the distance covered sprinting, with Top 4 teams covering greater sprinting distances than Bottom 4 teams. Top 4 teams made more meters in attack and conceded fewer meters in defense than Bottom 4 teams. Bottom 4 teams had a greater percentage of slow play-the-balls in defense than Top 4 teams (74.8% ± 7.3% vs 67.2% ± 8.3%). Middle 4 teams showed the greatest reduction in high-speed running from the first to the second half (–20.4%), while Bottom 4 teams completed 14.3% more high-speed running in the second half than in the first half.

Conclusion:

These findings demonstrate that a combination of activity profiles and technical and tactical performance are associated with playing success in semiprofessional rugby league players.