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This study identified and profiled the types of player actions of Australian football players executed during high acceleration and/or deceleration efforts and identified how the duration exceeding the acceleration or deceleration threshold influenced the identified executed player actions. The commencing speed of the acceleration and deceleration efforts were also assessed. Acceleration and deceleration efforts of 22 Australian football players monitored with a 10-Hz GNSS device across two matches were analysed. Synchronised video footage of the matches was used to identify the player actions executed during acceleration and deceleration efforts. Linear mixed models were conducted to examine the relationship between commencing speed, player action, and duration exceeding the effort threshold. 'Linear movement' and 'jump' were the most frequently executed player actions for high accelerations and 'stop' and 'being tackled' for high decelerations. Significant differences were observed in commencing speed between player actions for the high deceleration efforts. Furthermore, it was found that a higher commencing speed was associated with an increased duration exceeding the deceleration threshold. These findings will help practitioners and researchers with selecting minimum-duration criteria for acceleration and deceleration efforts and provide an understanding of the types of player actions executed during these efforts.

This study examines differences in weekly load between the first (FT) and the under 19 team (U19) within a professional football setting. Data were collected in 11 FT and 9 U19 players (2016-2017 season). FT data was divided into weeks with (FT-M1) or without (FT-M0) a mid-week match. Indicators were total distance (TD) and TD at 12-15, 15-20, 20-25 and >25 km‧h-1 and were analysed as external load (m), intensity (m‧min-1) and load monotony (a.u.). TD-based load was higher for U19 compared to FT-M0 (very likely moderate) and FT-M1 (likely large). Differences at higher velocities were substantially less (trivial to possibly small), with TD >25 km‧h-1 being lower than FT-M0 (very likely moderate) and FT-M1 (likely small). All intensity indicators were lower for U19 (likely small to almost certainly large). Load monotony was higher compared to FT-M1 (possibly small to almost certainly very large). Compared to FT-M0, monotony was higher for TD (possibly very large) and TD >25 km‧h‑1 (possibly moderate) but lower for TD 12-15 (possibly small) and 15-20 km‧h‑1 (likely moderate). So, despite higher weekly external loads at low velocity for elite youth players, external intensity and load variation increases when these players may transition to professional football. ispartof: Science and Medicine in Football vol:5 issue:1 ispartof: location:England status: published

Talent identification (TID) and development (TDE) are large fields in professional soccer and in science. However, TID and TDE processes in youth academies have not been assessed in detail. As such, our aim was to survey professional clubs from around the world about their youth academy TID and TDE processes, with 29 clubs responding to the survey. TID and TDE processes changed as a function of player age. TID processes involved finding the best players locally and regionally, but for older players the search widened to nationally and internationally for the needs of the first team. Clubs used a multidisciplinary approach to TID, but more so with older players. Median number of academy players was 80, 100, and 66 players at 8-11 years, 12-16 years, and 17-21 years, respectively. Annual player turnover in the most recent season (selections/de-selections) was 29% across all age groups, with competition from other clubs cited as a limitation to TID. TDE processes involved weekly matches and 3-5 training sessions per week led by experienced, well-qualified coaches, with most clubs providing players with academic education, residency and transportation services. Our findings extend previous research assessing professional soccer youth academy TID and TDE processes by quantifying worldwide practices.

This study assessed the interchangeability between 10-Hz multi-GNSS GPS devices (Vector®) and two optical tracking systems (TRACAB® and Second Spectrum®). The agreement between data from the optical tracking systems when processed with manufacturer and GPS-filtered software was also assessed. Thirty players competing in the English Premier League were monitored using three different tracking systems across five matches. To determine the interchangeability between systems, player movement variables including, total distance, high-speed running distance (19.8-25.2 km·h

Purpose: Using elite youth soccer players’ maximal sprinting speeds collected from a criterion and non-criterion measure, we demonstrate how expert practitioner opinion can be used to determine measurement validity. Methods: Expert soccer practitioners (n = 50) from around the world were surveyed on issues relating to the measurement of maximal sprinting speed and 12 elite youth soccer players performed two maximal 40 m sprints, measured by 10-Hz GPS units (non-criterion) and a 100-Hz Laser (criterion). Setting statistical equivalence bounds as practitioner opinion of the practically acceptable amount of measurement error for maximal sprinting speed, we assessed agreement between GPS and Laser. Results: Survey respondents reported a combination of methods for deriving maximal sprinting speed (tests, training, match) but most did not assess system validity. Median value of the practically acceptable amount of measurement error for maximal sprinting speed was 0.20 m/s. Maximal sprinting speed was 8.79 ± 0.33 m/s (Laser) and 8.75 ± 0.32 m/s (GPS), and the mean difference was 0.04 (90% confidence interval −0.03 to 0.11) m/s. Using the median acceptable amount of measurement error, we set our lower and upper equivalence bounds to −0.10 m/s and +0.10 m/s, respectively. Equivalence testing showed Laser and GPS as likely equivalent measures (probability 93.7%). Conclusion: Using expert-informed equivalence thresholds represents a novel way to assess validity in sports performance research. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

Trewin, J, Meylan, C, Varley, MC, Cronin, J, and Ling, D. Effect of match factors on the running performance of elite female soccer players. J Strength Cond Res 32(7): 2002-2009, 2018-The purpose of this study was to examine the effects of match factors on the match running of elite female soccer players. Players from the same women's national team (n = 45) were monitored during 47 international fixtures (files = 606) across 4 years (2012-2015) using 10-Hz global positioning system devices. A mixed model was used to analyze the effects of altitude, temperature, match outcome, opposition ranking, and congested schedules. At altitude (>500 m), a small increase in the number of accelerations (effect size [ES] = 0.40) and a small decrease in total distance (ES = -0.54) were observed, whereas at higher temperatures, there were decreases in all metrics (ES = -0.83 to -0.16). Playing a lower ranked team in a draw resulted in a moderate increase in high-speed running (ES = 0.89), with small to moderate decreases in total distance and low-speed running noted in a loss or a win. Winning against higher ranked opponents indicated moderately higher total distance and low-speed running (ES = 0.75), compared with a draw. Although the number of accelerations were higher in a draw against lower ranked opponents, compared with a win and a loss (ES = 0.95 and 0.89, respectively). Practitioners should consider the effect of match factors on match running in elite female soccer.

Objectives The purpose of this study was to examine the match-to-match variation of match-running in elite female soccer players utilising GPS, using full-match and rolling period analyses. Design Longitudinal study. Methods Elite female soccer players (n = 45) from the same national team were observed during 55 international fixtures across 5 years (2012–2016). Data was analysed using a custom built MS Excel spreadsheet as full-matches and using a rolling 5-min analysis period, for all players who played 90-min matches (files = 172). Variation was examined using co-efficient of variation and 90% confidence limits, calculated following log transformation. Results Total distance per minute exhibited the smallest variation when both the full-match and peak 5-min running periods were examined (CV = 6.8–7.2%). Sprint-efforts were the most variable during a full-match (CV = 53%), whilst high-speed running per minute exhibited the greatest variation in the post-peak 5-min period (CV = 143%). Peak running periods were observed as slightly more variable than full-match analyses, with the post-peak period very-highly variable. Variability of accelerations (CV = 17%) and Player Load (CV = 14%) was lower than that of high-speed actions. Positional differences were also present, with centre backs exhibiting the greatest variation in high-speed movements (CV = 41–65%). Conclusions Practitioners and researchers should account for within player variability when examining match performances. Identification of peak running periods should be used to assist worst case scenarios. Whilst micro-sensor technology should be further examined as to its viable use within match-analyses.

It is common practice amongst researchers and practitioners to monitor the effects of external load via electronic tracking systems. Both semi-automatic multiple camera systems and global positioni...

© 2017 Human Kinetics, Inc. Monitoring the load placed on athletes in both training and competition has become a very hot topic in sport science. Both scientists and coaches routinely monitor training loads using multidisciplinary approaches, and the pursuit of the best methodologies to capture and interpret data has produced an exponential increase in empirical and applied research. Indeed, the field has developed with such speed in recent years that it has given rise to industries aimed at developing new and novel paradigms to allow us to precisely quantify the internal and external loads placed on athletes and to help protect them from injury and ill health. In February 2016, a conference on "Monitoring Athlete Training Loads-The Hows and the Whys" was convened in Doha, Qatar, which brought together experts from around the world to share their applied research and contemporary practices in this rapidly growing field and also to investigate where it may branch to in the future. This consensus statement brings together the key findings and recommendations from this conference in a shared conceptual framework for use by coaches, sport-science and-medicine staff, and other related professionals who have an interest in monitoring athlete training loads and serves to provide an outline on what athlete-load monitoring is and how it is being applied in research and practice, why load monitoring is important and what the underlying rationale and prospective goals of monitoring are, and where athlete-load monitoring is heading in the future.

Passing ability is of great importance in the development of young football players. The Loughborough Soccer Passing Test (LSPT) was developed to assess short-distance passing ability under time pressure, in a controlled environment. While the test has strong discriminant validity and acceptable test–retest reliability, no information exists on its ability to predict passing performance during a game. The aim of the present study was to assess the criterion validity of the LSPT in elite youth football players. Twenty-four outfield male players from an U18 state-representative team performed the LSPT. Criterion measures of passing performance overall and in high-difficulty scenarios were provided by video analysis of the first eight subsequent games of a competitive season. Validity was quantified as Pearson’s correlations between the LSPT score (total and time-only) and the two criterion measures, adjusted for reliability of the criterion measures. The adjusted correlations ranged from 0.30 (90% c...

This study investigated the positional differences in physical performance of elite youth footballers in a tournament scenario and the influence of team success and opponent quality on team physical and technical performance. Match performance observations were collected using a semi-automated multi-camera tracking system across 2 elite under-17 international club tournaments from all players and teams (n = 1,457 individual cases). Teams were classified based on their final tournament ranking as top (1–4 ranking), middle (5–8 ranking) and bottom (9–12 ranking). Technical performance measures were expressed in absolute terms and relative to the time the team was in ball possession. Positional differences in physical performance and the influence of team success and opponent quality on team match performance were identified using a generalised linear mixed model. Positional differences were similar to that observed in elite senior players. Top ranking teams performed a greater number of absolute and...

Objectives To investigate the impact of physical efforts performed in the period preceding activity as a potential risk factor of muscle injury during match-play within a sample of professional soccer players. Design Observational cohort study. Methods Match load (running [>14.4–19.8 km/h], high-speed running [>19.8–25.2 km/h], sprinting [>25.2 km/h], leading and explosive sprint type) averaged in 1-min and 5-min periods prior to an event or non event for 29 professional outfield soccer players. Conditional logistic and Poisson regression models estimated the relationship between load and injury for a 2 within-subject standard deviation in match load or 1-action increment in the number of sprinting activities, respectively. Associations were deemed beneficial or harmful based on non-overlap of the 95% confidence intervals against thresholds of 0.90 and 1.11, respectively. Results An increment in sprinting distance [+2-SDs = 11 m] covered over a 1-min period (odds ratio [OR]: 1.22, 95%CI, 1.12 to 1.33) increased the odds of muscle injury. Conclusions Our study provides novel exploratory evidence that the volume of sprinting during competitive soccer match-play has a harmful association with muscle injury occurrence.

Purpose:To investigate the influence of score line, level of opposition, and timing of substitutes on the activity profile of rugby sevens players and describe peak periods of activity.Methods:Velocity and distance data were measured via 10-Hz GPS from 17 international-level male rugby sevens players on 2–20 occasions over 4 tournaments (24 matches). Movement data were reported as total distance (TD), high-speed-running distance (HSR, 4.17−10.0 m/s), and the occurrence of maximal accelerations (Accel, ≥2.78 m/s2). A rolling 1-min sample period was used.Results:Regardless of score line or opponent ranking there was a moderate to large reduction in average and peak TD and HSR between match halves. A close halftime score line was associated with a greater HSR distance in the 1st minute of the 1st and 2nd halves compared with when winning. When playing against higher-compared with lower-ranked opposition, players covered moderately greater TD in the 1st minute of the 1st half (difference = 26%; 90% confidence limits = 6, 49). Compared with players who played a full match, substitutes who came on late in the 2nd half had a higher average HSR and Accel by a small magnitude (31%; 5, 65 vs 34%; 6, 69) and a higher average TD by a moderate magnitude (16%; 5, 28).Conclusions:Match score line, opposition, and substitute timing can influence the activity profile of rugby sevens players. Players are likely to perform more running against higher opponents and when the score line is close. This information may influence team selection.

This study investigated the effects of successive matches on match-running in elite under-23 soccer players during an international tournament. Match-running data was collected using a semi-automated multi-camera tracking system during an international under-23 tournament from all participating outfield players. Players who played 100% of all group stage matches were included (3 matches separated by 72 h, n = 44). Differences in match-running performance between matches were identified using a generalised linear mixed model. There were no clear effects for total, walking, jogging, running, high-speed running and sprinting distance between matches 1 and 3 (effect size (ES); -0.32 to 0.05). Positional analysis found that sprint distance was largely maintained from matches 1 to 3 across all positions. Attackers had a moderate decrease in total, jogging and running distance between matches 1 and 3 (ES; -0.72 to -0.66). Classifying players as increasers or decreasers in match-running revealed that match-running changes are susceptible to individual differences. Sprint performance appears to be maintained over successive matches regardless of playing position. However, reductions in other match-running categories vary between positions. Changes in match-running over successive matches affect individuals differently; thus, players should be monitored on an individual basis.

© 2017 Human Kinetics, Inc. Athlete-tracking devices that include global positioning system (GPS) and microelectrical mechanical system (MEMS) components are now commonplace in sport research and practice. These devices provide large amounts of data that are used to inform decision making on athlete training and performance. However, the data obtained from these devices are often provided without clear explanation of how these metrics are obtained. At present, there is no clear consensus regarding how these data should be handled and reported in a sport context. Therefore, the aim of this review was to examine the factors that affect the data produced by these athlete-tracking devices and to provide guidelines for collecting, processing, and reporting of data. Many factors including device sampling rate, positioning and fitting of devices, satellite signal, and data-filtering methods can affect the measures obtained from GPS and MEMS devices. Therefore researchers are encouraged to report device brand/model, sampling frequency, number of satellites, horizontal dilution of precision, and software/firmware versions in any published research. In addition, details of inclusion/exclusion criteria for data obtained from these devices are also recommended. Considerations for the application of speed zones to evaluate the magnitude and distribution of different locomotor activities recorded by GPS are also presented, alongside recommendations for both industry practice and future research directions. Through a standard approach to data collection and procedure reporting, researchers and practitioners will be able to make more confident comparisons from their data, which will improve the understanding and impact these devices can have on athlete performance.

Introduction: Afferent information from exercising muscle contributes to the sensation of exercise-induced muscle pain. Transcutaneous electrical nerve stimulation (TENS) delivers low–voltage electrical currents to the skin, inhibiting nociceptive afferent information. The use of TENS in reducing perceptions of exercise-induced pain has not yet been fully explored. This study aimed to investigate the effect of TENS on exercise-induced muscle pain, pacing strategy, and performance during a 5-km cycling time trial (TT). Methods: On three separate occasions, in a single-blind, randomized, and cross-over design, 13 recreationally active participants underwent a 30-min TENS protocol, before performing a 5-km cycling TT. TENS was applied to the quadriceps prior to exercise under the following conditions; control (CONT), placebo with sham TENS application (PLAC), and an experimental condition with TENS application (TENS). Quadriceps fatigue was assessed with magnetic femoral nerve stimulation assessing changes in potentiated quadriceps twitch force at baseline, pre and post exercise. Subjective scores of exertion, affect and pain were taken every 1-km. Results: During TTs, application of TENS did not influence pain perceptions (P = 0.68, ηp2 = 0.03). There was no significant change in mean power (P = 0.16, ηp2 = 0.16) or TT duration (P = 0.17, ηp2 = 0.14), although effect sizes were large for these two variables. Changes in power output were not significant but showed moderate effect sizes at 500-m (ηp2 = 0.10) and 750-m (ηp2 = 0.10). Muscle recruitment as inferred by electromyography data was not significant, but showed large effect sizes at 250-m (ηp2 = 0.16), 500-m (ηp2 = 0.15), and 750-m (ηp2 = 0.14). This indicates a possible effect for TENS influencing performance up to 1-km. Discussion: These findings do not support the use of TENS to improve 5-km TT performance.

We compared the match activity profiles of elite footballers from Australian football (AF), rugby league (RL) and soccer (SOC), using identical movement definitions. Ninety-four elite footballers from AF, RL or SOC clubs in Australia participated in this study. Movement data were collected using a 5-Hz global positioning system from matches during the 2008–2011 competitive seasons, including measures of velocity, distance, acceleration and bouts of repeat sprints (RS). Australian footballers covered the greatest relative running distances (129 ± 17 m.min−1) compared to RL (97 ± 16 m.min−1) and SOC (104 ± 10 m.min−1) (effect size [ES]; 1.0–2.8). The relative distance covered (4.92 ± 2.10 m.min−1 vs. 5.42 ± 2.49 m.min−1; 0.74 ± 0.78 m.min−1 vs. 0.97 ± 0.80 m.min−1) and the number of high-velocity running (0.4 ± 0.2 no.min−1 vs. 0.4 ± 0.2 no.min−1) and sprint (0.06 ± 0.06 no.min−1 vs. 0.08 ± 0.07 no.min−1) efforts between RL and SOC players were similar (ES; 0.1–0.3). Rugby league players undertook t...

Purpose:Sprints and accelerations are popular performance indicators in applied sport. The methods used to define these efforts using athlete-tracking technology could affect the number of efforts reported. This study aimed to determine the influence of different techniques and settings for detecting high-intensity efforts using global positioning system (GPS) data.Methods:Velocity and acceleration data from a professional soccer match were recorded via 10-Hz GPS. Velocity data were filtered using either a median or an exponential filter. Acceleration data were derived from velocity data over a 0.2-s time interval (with and without an exponential filter applied) and a 0.3-second time interval. High-speed-running (≥4.17 m/s2), sprint (≥7.00 m/s2), and acceleration (≥2.78 m/s2) efforts were then identified using minimum-effort durations (0.1–0.9 s) to assess differences in the total number of efforts reported.Results:Different velocity-filtering methods resulted in small to moderate differences (effect size [ES] 0.28–1.09) in the number of high-speed-running and sprint efforts detected when minimum duration was Conclusions:Filtering techniques and minimum durations substantially affect the number of high-speed-running, sprint, and acceleration efforts detected with GPS. Changes to how high-intensity efforts are defined affect reported data. Therefore, consistency in data processing is advised.

The need to quantify aspects of training to improve training prescription has been the holy grail of sport scientists and coaches for many years. Recently, there has been an increase in scientific interest, possibly due to technological advancements and better equipment to quantify training activities. Over the last few years there has been an increase in the number of studies assessing training load in various athletic cohorts with a bias toward subjective reports and/or quantifications of external load. There is an evident lack of extensive longitudinal studies employing objective internal-load measurements, possibly due to the cost-effectiveness and invasiveness of measures necessary to quantify objective internal loads. Advances in technology might help in developing better wearable tools able to ease the difficulties and costs associated with conducting longitudinal observational studies in athletic cohorts and possibly provide better information on the biological implications of specific external-load patterns. Considering the recent technological developments for monitoring training load and the extensive use of various tools for research and applied work, the aim of this work was to review applications, challenges, and opportunities of various wearable technologies.

Purpose: To quantify the effect of acute hypoxia on muscle oxygenation and power during simulated team-sport running. Methods: Seven individuals performed repeated and single sprint efforts, embedded in a simulated team-sport running protocol, on a non-motorized treadmill in normoxia (sea-level), and acute normobaric hypoxia (simulated altitudes of 2,000 and 3,000 m). Mean and peak power was quantified during all sprints and repeated sprints. Mean total work, heart rate, blood oxygen saturation, and quadriceps muscle deoxyhaemoglobin concentration (assessed via near-infrared spectroscopy) were measured over the entire protocol. A linear mixed model was used to estimate performance and physiological effects across each half of the protocol. Changes were expressed in standardized units for assessment of magnitude. Uncertainty in the changes was expressed as a 90% confidence interval and interpreted via non-clinical magnitude-based inference. Results: Mean total work was reduced at 2,000 m (−10%, 90% confidence limits ±6%) and 3,000 m (−15%, ±5%) compared with sea-level. Mean heart rate was reduced at 3,000 m compared with 2,000 m (−3, ±3 min−1) and sea-level (−3, ±3 min−1). Blood oxygen saturation was lower at 2,000 m (−8, ±3%) and 3,000 m (−15, ±2%) compared with sea-level. Sprint mean power across the entire protocol was reduced at 3,000 m compared with 2,000 m (−12%, ±3%) and sea-level (−14%, ±4%). In the second half of the protocol, sprint mean power was reduced at 3,000 m compared to 2,000 m (−6%, ±4%). Sprint mean peak power across the entire protocol was lowered at 2,000 m (−10%, ±6%) and 3,000 m (−16%, ±6%) compared with sea-level. During repeated sprints, mean peak power was lower at 2,000 m (−8%, ±7%) and 3,000 m (−8%, ±7%) compared with sea-level. In the second half of the protocol, repeated sprint mean power was reduced at 3,000 m compared to 2,000 m (−7%, ±5%) and sea-level (−9%, ±5%). Quadriceps muscle deoxyhaemoglobin concentration was lowered at 3,000 m compared to 2,000 m (−10, ±12%) and sea-level (−11, ±12%). Conclusions: Simulated team-sport running is impaired at 3,000 m compared to 2,000 m and sea-level, likely due to a higher muscle deoxygenation.

We quantified the acceleration and high-velocity running of elite Australian soccer players. We hypothesised that high-intensity activity would be underestimated when excluding acceleration during match analysis given its high metabolic demand and occurrence at low velocities. Player movements were observed from 29 players (forwards and central and wide defenders and midfielders) during domestic Australian competition using 5-Hz global positioning system. Effort occurrence were determined for high-velocity running, sprinting and maximal accelerations. The commencement and final velocity of maximal accelerations were also identified. Players undertook an 8~fold greater number of maximal accelerations than sprints per game (65±21 vs. 8±5). Of maximal accelerations ~98% commenced from a starting velocity lower than what would be considered high-velocity running while ~85% did not cross the high-velocity running threshold. The number of efforts performed in all categories were position dependent (P

Aims To examine the oxygen (O2) kinetics during early recovery from peak exercise in patients with Type 2 diabetes and to examine whether oxygen O2 recovery is associated with fasting glucose and HbA1c in this population. Methods Eighty-nine participants (52 men) aged 51.8 ± 7.1 years (mean ± sd) were divided into three groups: normal weight (BMI ≤ 25.0 kg/m2), overweight/obese without diabetes (BMI ≥ 26 kg/m2) and overweight/obese with Type 2 diabetes. Participants were assessed for their aerobic power (VO2peak) on a cycle ergometer, provided a fasting blood sample and underwent a series of anthropometric measurements. Early recovery period was measured for 60 s from cessation of exercise and expressed as percentage of VO2peak (higher percentage represents slower recovery). Results No significant differences were observed for age between the three study groups. Both the overweight/obese groups without diabetes and with Type 2 diabetes had higher BMI than the normal weight group, with no significant differences between overweight/obese participants without diabetes and those with diabetes. Participants with Type 2 diabetes had lower VO2peak than overweight/obese participants without diabetes and normal weight individuals (19.6 ± 4.8, 22.6 ± 5.4 and 25.7 ± 5.3 ml kg−1 min−1, respectively, P < 0.004 for overall trends). Participants with Type 2 diabetes also had slower recovery in oxygen O2 kinetics after exercise, compared with both normal weight and overweight/obese individuals without diabetes (56.5 ± 7.7, 49.2 ± 7.2, 47.7 ± 7.4%, P < 0.004 for overall trends). Multiple regression analysis revealed that percentage of oxygen O2 recovery was a stronger predictor than VO2peak, BMI or age for fasting glucose and HbA1c. Conclusions Patients with Type 2 diabetes have lower VO2peak and prolonged oxygen O2 recovery from peak exercise. However, only prolonged oxygen O2 recovery was associated with fasting glucose and HbA1c.

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.

The question of whether altitude training can enhance subsequent sea-level performance has been well investigated over many decades. However, research on this topic has focused on athletes from individual or endurance sports, with scant number of studies on team-sport athletes. Questions that need to be answered include whether this type of training may enhance team-sport athlete performance, when success in team-sport is often more based on technical and tactical ability rather than physical capacity per se. This review will contrast and compare athletes from two sports representative of endurance (cycling) and team-sports (soccer). Specifically, we draw on the respective competition schedules, physiological capacities, activity profiles and energetics of each sport to compare the similarities between athletes from these sports and discuss the relative merits of altitude training for these athletes. The application of conventional live-high, train-high; live-high, train-low; and intermittent hypoxic training for team-sport athletes in the context of the above will be presented. When the above points are considered, we will conclude that dependent on resources and training objectives, altitude training can be seen as an attractive proposition to enhance the physical performance of team-sport athletes without the need for an obvious increase in training load.

Objectives We investigated the effect of high altitude on the match activity profile of elite youth high altitude and sea level residents. Methods Twenty Sea Level (Australian) and 19 Altitude-resident (Bolivian) soccer players played five games, two near sea level (430 m) and three in La Paz (3600 m). Match activity profile was quantified via global positioning system with the peak 5 min period for distance ((D5peak)) and high velocity running (>4.17 m/s, HIVR5peak); as well as the 5 min period immediately subsequent to the peak for both distance (D5sub) and high-velocity running (HIVR5sub) identified using a rolling 5 min epoch. The games at 3600 m were compared with the average of the two near sea-level games. Results The total distance per minute was reduced by a small magnitude in the first match at altitude in both teams, without any change in low-velocity running. There were variable changes in HiVR, D5peak and HiVR5peak from match to match for each team. There were within-team reductions in D5peak in each game at altitude compared with those at near sea level, and this reduction was greater by a small magnitude in Australians than Bolivians in game 4. The effect of altitude on HiVR5peak was moderately lower in Australians compared with Bolivians in game 3. There was no clear difference in the effect of altitude on maximal accelerations between teams. Conclusions High altitude reduces the distance covered by elite youth soccer players during matches. Neither 13 days of acclimatisation nor lifelong residence at high altitude protects against detrimental effects of altitude on match activity profile. Refereed/Peer-reviewed

Purpose:The efficacy of a single exposure to 14 min of contrast water therapy (CWT) or cold-water immersion (COLD) on recovery postmatch in elite professional footballers was investigated.Method:Twenty-four elite footballers participated in a match followed by 1 of 3 recovery interventions. Recovery was monitored for 48 h postmatch. Repeat-sprint ability (6 × 20-m), static and countermovement jump performance, perceived soreness, and fatigue were measured prematch and immediately, 24 h, and 48 h after the match. Soreness and fatigue were also measured 1 h postmatch. Postmatch, players were randomly assigned to complete passive recovery (PAS; n = 8), COLD (n = 8), or CWT (n = 8).Results:Immediately postmatch, all groups exhibited similar psychometric and performance decrements, which persisted for 48 h only in the PAS group. Repeatsprinting performance remained slower at 24 and 48 h for PAS (3.9% and 2.0%) and CWT (1.6% and 0.9%) but was restored by COLD (0.2% and 0.0%). Soreness after 48 h was most effectively attenuated by COLD (ES 0.59 ± 0.10) but remained elevated for CWT (ES 2.39 ± 0.29) and PAS (ES 4.01 ± 0.97). Similarly, COLD more successfully reduced fatigue after 48 h (ES 1.02 ± 0.72) than did CWT (ES 1.22 ± 0.38) and PAS (ES 1.91 ± 0.67). Declines in static and countermovement jump were ameliorated best by COLD.Conclusions:An elite professional football match results in prolonged physical and psychometric deficits for 48 h. COLD was more successful at restoring physical performance and psychometric measures than CWT, with PAS being the poorest.

Purpose:The authors investigated the efficacy of a single exposure to 14 min of cold-water immersion (COLD) and contrast water therapy (CWT) on posttraining recovery in Australian football (AF).Method:Fourteen AF players participated in 3 wk of standardized training. After week 1 training, all players completed a passive recovery (PAS). During week 2, COLD or CWT was randomly assigned. Players undertook the opposing intervention in week 3. Repeat-sprint ability (6 × 20 m), countermovement and squat jumps, perceived muscle soreness, and fatigue were measured pretraining and over 48 h posttraining.Results:Immediately posttraining, groups exhibited similar performance and psychometric declines. At 24 h, repeat-sprint time had deteriorated by 4.1% for PAS and 1.0% for CWT but was fully restored by COLD (0.0%). At 24 and 48 h, both COLD and CWT attenuated changes in mean muscle soreness, with COLD (0.6 ± 0.6 and 0.0 ± 0.4) more effective than CWT (1.9 ± 0.7 and 1.0 ± 0.7) and PAS having minimal effect (5.5 ± 0.6 and 4.0 ± 0.5). Similarly, after 24 and 48 h, COLD and CWT both effectively reduced changes in perceived fatigue, with COLD (0.6 ± 0.6 and 0.0 ± 0.6) being more successful than CWT (0.8 ± 0.6 and 0.7 ± 0.6) and PAS having the smallest effect (2.2 ± 0.8 and 2.4 ± 0.6).Conclusions:AF training can result in prolonged physical and psychometric deficits persisting for up to 48 h. For restoring physical-performance and psychometric measures, COLD was more effective than CWT, with PAS being the least effective. Based on these results the authors recommend that 14 min of COLD be used after AF training.

In this study, we assessed the validity and reliability of 5 and 10 Hz global positioning systems (GPS) for measuring instantaneous velocity during acceleration, deceleration, and constant velocity while straight-line running. Three participants performed 80 running trials while wearing two GPS units each (5 Hz, V2.0 and 10 Hz, V4.0; MinimaxX, Catapult Innovations, Scoresby, VIC, Australia). The criterion measure used to assess GPS validity was instantaneous velocity recorded using a tripod-mounted laser. Validity was established using the standard error of the estimate (± 90% confidence limits). Reliability was determined using typical error (± 90% confidence limits, expressed as coefficient of variation) and Pearson's correlation. The 10 Hz GPS devices were two to three times more accurate than the 5 Hz devices when compared with a criterion value for instantaneous velocity during tasks completed at a range of velocities (coefficient of variation 3.1-11.3%). Similarly, the 10 Hz GPS units were up to six-fold more reliable for measuring instantaneous velocity than the 5 Hz units (coefficient of variation 1.9-6.0%). Newer GPS may provide an acceptable tool for the measurement of constant velocity, acceleration, and deceleration during straight-line running and have sufficient sensitivity for detecting changes in performance in team sport. However, researchers must account for the inherent match-to-match variation reported when using these devices.