2010) 'Motion analysis of match-play in elite U12 to U16 age-group soccer players', Journal of Sp... more 2010) 'Motion analysis of match-play in elite U12 to U16 age-group soccer players', Journal of Sports Sciences,, First published on
International Journal of Sports Physiology and Performance, 2014
To quantify the effects of a 12-wk isolated core-training program on 50-m front-crawl swim time a... more To quantify the effects of a 12-wk isolated core-training program on 50-m front-crawl swim time and measures of core musculature functionally relevant to swimming. Twenty national-level junior swimmers (10 male and 10 female, 16 ± 1 y, 171 ± 5 cm, 63 ± 4 kg) participated in the study. Group allocation (intervention [n = 10], control [n = 10]) was based on 2 preexisting swim-training groups who were part of the same swimming club but trained in different groups. The intervention group completed the core training, incorporating exercises targeting the lumbopelvic complex and upper region extending to the scapula, 3 times/wk for 12 wk. While the training was performed in addition to the normal pool-based swimming program, the control group maintained their usual pool-based swimming program. The authors made probabilistic magnitude-based inferences about the effect of the core training on 50-m swim time and functionally relevant measures of core function. Compared with the control group, the core-training intervention group had a possibly large beneficial effect on 50-m swim time (-2.0%; 90% confidence interval -3.8 to -0.2%). Moreover, it showed small to moderate improvements on a timed prone-bridge test (9.0%; 2.1-16.4%) and asymmetric straight-arm pull-down test (23.1%; 13.7-33.4%), and there were moderate to large increases in peak EMG activity of core musculature during isolated tests of maximal voluntary contraction. This is the first study to demonstrate a clear beneficial effect of isolated core training on 50-m front-crawl swim performance.
To examine the within- and between-player variability of physical performance and player match lo... more To examine the within- and between-player variability of physical performance and player match loads in professional rugby union. A single cohort, observational study. Physical match performance data were collected from 28 male, professional, English Championship players over 15 competitive matches. Using microsensors, the variables selected for analysis were total distance, low-speed running distance, high-speed running distance, very high-speed running distance, total impacts, repeated high-intensity efforts, body load (PlayerLoad™), and low velocity (<7.2kmh(-1)) body load. Ratings of perceived exertion represented match internal loads. Variability was quantified using the coefficient of variation, with the meaningful interpretation of change in physical performance and match loads calculated using magnitude-based inferences. We found large between-match (within-player) variation for high-speed running distance (27.6%; ±90% confidence limits 6.9% [forwards], 20.1%; ±4.1% [backs]), very high-speed running distance (68%; ±19%, 34.1%; ±7.5%), total impacts (24.0%; ±5.9%, 36.4%; ±7.9%) and repeated high-intensity efforts (18.7%; ±4.4%, 39.5%; ±8.8%), with moderate variability for match ratings of perceived exertion (8.2%; ±1.8%, 10.8%; ±2.1%), body load (7.3%; ±1.7%, 10.0%; ±2.0%) and low velocity body load (8.9%; ±2.0%, 10.7%; ±2.1%). Threshold values for likely substantial between-match changes in high-intensity physical performance measures ranged from 21% to 76%, and were ∼10% for match ratings of perceived exertion, body load and low velocity body load. Within- and between-player variability of high-intensity activity in professional rugby union is large, yet ratings of perceived exertion, body load and low velocity body load appear more stable by comparison and may be interpreted with greater accuracy.
Intervention fidelity refers to the degree to which an experimental manipulation has been impleme... more Intervention fidelity refers to the degree to which an experimental manipulation has been implemented as intended, but simple, robust methods for quantifying fidelity have not been well documented. Therefore, we aim to illustrate a rigorous quantitative evaluation of intervention fidelity, using data collected during a high-intensity interval training intervention. Single-group measurement study. Seventeen adolescents (mean age ± standard deviation [SD] 14.0 ± 0.3 years) attended a 10-week high-intensity interval training intervention, comprising two exercise sessions per week. Sessions consisted of 4-7 45-s maximal effort repetitions, interspersed with 90-s rest. We collected heart rate data at 5-s intervals and recorded the peak heart rate for each repetition. The high-intensity exercise criterion was ≥ 90% of individual maximal heart rate. For each participant, we calculated the proportion of total exercise repetitions exceeding this threshold. A linear mixed model was applied to properly separate the variability in peak heart rate between- and within-subjects. Results are presented both as intention to treat (including missed sessions) and per protocol (only participants with 100% attendance; n=8). For intention to treat, the median (interquartile range) proportion of repetitions meeting the high-intensity criterion was 58% (42% to 68%). The mean peak heart rate was 85% of maximal, with a between-subject SD of 7.8 (95% confidence interval 5.4 to 11.3) percentage points and a within-subject SD of 15.1 (14.6 to 15.6) percentage points. For the per protocol analysis, the median proportion of high-intensity repetitions was 68% (47% to 86%). The mean peak heart rate was 91% of maximal, with between- and within-subject SDs of 3.1 (-1.3 to 4.6) and 3.4 (3.2 to 3.6) percentage points, respectively. Synthesising information on exercise session attendance and compliance (exercise intensity) quantifies the intervention dose and informs evaluations of treatment fidelity.
To perform an exploratory characterization of repeated sprint sequences (RSS) and repeated accele... more To perform an exploratory characterization of repeated sprint sequences (RSS) and repeated acceleration sequences (RAS) in top level soccer referees. 7 field and 7 assistant referees were monitored during 2007 America's Soccer Cup with GPS technology. Sprints of >18 km·h(-1) and accelerations of >1.5 m·s(-2) were considered as high intensity activities. RSS and RAS were defined as a minimum of 3 consecutive bouts interspersed with a maximum of 45 s. Field and assistant referees performed substantially more accelerations than sprints. Neither field nor assistant referees recorded any RSS. In contrast, total distance performing RAS amounted to ∼37% and ∼20% of the total distance covered by accelerations during the entire match for field and assistant referees, respectively. Only field referees exhibited fatigue-related reductions in RAS characteristics between halves. The results of the present study would appear to support the appropriateness of a repeated acceleration abil...
We were interested to read the recent article by Mugglestone et al. [9], which examined high-spee... more We were interested to read the recent article by Mugglestone et al. [9], which examined high-speed running performances of University soccer players during the early stages of each half in competitive match-play. The data is a welcome addition to a small body of work examining the within-match trends in soccer work rate, with particular reference to the half-time interval and its impact upon players' subsequent physical performances. In this letter we direct the authors to several relevant studies that were not considered in their article . We hope that by highlighting these research contributions to the authors and readership, interpretation of withinmatch analysis trends can be undertaken with necessary due care and caution.
The aim of the present study was to determine the between-match variability in soccer referees... more The aim of the present study was to determine the between-match variability in soccer referees' match performances. 1 269 individual match observations were undertaken on 59 referees (range 2-79 games per referee) officiating in the English Premier League and Championship from 2003/2004 to 2007/2008 using a computerised tracking system (Prozone (®), Leeds, England). Between-match coefficients of variation (CV) were calculated for all games and then compared between referee age and experience groups. High mean CVs were observed for high-speed running distance (25.9±10.1%), recovery time (32.7±13.8%), explosive sprints (34.3±16.6%), total number of sprints (54.0±20.7%) and number of match fouls (28±4.6%). Smaller CVs were observed for total distance covered (3.8±1.5%), top sprinting speed (5.6±10.9%), distance from the ball (4.2±1.9%) and the distance from fouls (9.9±4.3%). Variability in match activities was not influenced by referee age or experience. The present study's fin...
International journal of sports physiology and performance, 2011
Athlete case studies have often focused on the training outcome and not the training process. Con... more Athlete case studies have often focused on the training outcome and not the training process. Consequently, there is a dearth of information detailing longitudinal training protocols, yet it is the combined assessment of both outcome and process that enhances the interpretation of physical test data. We were provided with a unique opportunity to assess the training load, physical match performance, and physiological fitness of an elite soccer referee from the referee's final season before attaining full-time, professional status (2002) until the season when he refereed the 2010 UEFA Champions League and FIFA World Cup finals. An increased focus on on-field speed and gym-based strength training was observed toward the end of the study period and longitudinal match data showed a tendency for decreased total distances but an increased intensity of movements. Laboratory assessments demonstrated that VO2max remained stable (52.3 vs 50.8 mL·kg-1·min-1), whereas running speed at the la...
Repeated-sprint training appears to be an efficient and practical means for the simultaneous deve... more Repeated-sprint training appears to be an efficient and practical means for the simultaneous development of different components of fitness relevant to team sports. Our objective was to systematically review the literature and meta-analyse the effect of repeated-sprint training on a selection of field-based measures of athletic performance, i.e. counter-movement jump, 10 m sprint, 20 m sprint, 30 m sprint, repeated-sprint ability and high-intensity intermittent running performance. The SPORTDiscus, PubMed, MEDLINE and Web of Science databases were searched for original research articles. Search terms included 'repeated-sprint training', 'sprint training', 'aerobic endurance', 'repeated-sprint ability', 'counter-movement jump' and 'sprint…
International journal of sports physiology and performance, 2011
Soccer referees' physical match performances at the start of the second half (46-60 min) were... more Soccer referees' physical match performances at the start of the second half (46-60 min) were evaluated in relation to both the corresponding phase of the first half (0-15 min) and players' performances during the same match periods. Match analysis data were collected (Prozone, UK) from 12 soccer referees on 152 English Premier League matches during the 2008/09 soccer season. Physical match performance categories for referees and players were total distance, high-speed running distance (speed >5.5 m/s), and sprinting distance (>7.0 m/s). The referees' heart rate was recorded from the start of their warm-up to the end of the match. The referees' average distances (in meters) from the ball and fouls were also calculated. No substantial differences were observed in duration (16:42 ± 2:35 vs 16:27 ± 1:00 min) or intensity (107 ± 11 vs 106 ± 14 beats/ min) of the referees' preparation periods immediately before each half. Physical match performance was reduced d...
The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarbo... more The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarbo-xylato)-ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombina...
To investigate the application of differential ratings of perceived exertion for the examination ... more To investigate the application of differential ratings of perceived exertion for the examination of internal load during Australian Football League (AFL) matches. Single cohort, observational study. Using the centiMax rating of perceived exertion (RPE) scale, 26 professional AFL players provided ratings for match exertion (RPE-M), along with differential ratings for breathlessness (RPE-B), leg exertion (RPE-L), and technical demand (RPE-T) following 129 matches (5.0±1.6 matches per player). Global positioning satellite (GPS) and accelerometer measures were also collected. Data were analysed using magnitude-based inferences. RPE scores were 93.0±8.2 AU (RPE-M), 89.0±11.0 AU (RPE-B), 91.5±9.8 AU (RPE-L), and 87.0±10.0 AU (RPE-T). There was a most likely small difference between RPE-L and RPE-T (5.5%; ±90% confidence limits 1.9%), a likely small difference between RPE-L and RPE-B (3.5%; ±1.5%) and a possibly small difference between RPE-B and RPE-T (1.9%; ±1.9%). Within-player correlations between RPE and GPS measures were small for RPE-M (r=0.14-0.28), unclear to small for RPE-B (r=0.06-0.24) and unclear to moderate for RPE-L (r=0.06-0.37). Differential RPE's combined to explain 76% of the variance in RPE-M. For all RPE scores, within-player variability was moderate to high (typical error: 7.9-12.4%), and the thresholds for a likely between-match change were 8.8-13.7%. As differential RPE's represent distinct sensory inputs, the collection of these scores facilitate the interpretation of internal match loads and therefore represent a valuable addition to match data collection procedures. Moderate to high within-player variability should be considered when interpreting between-match changes in all RPE scores.
ABSTRACT Study Background: The within-season variation in fitness measures of elite youth female ... more ABSTRACT Study Background: The within-season variation in fitness measures of elite youth female soccer players (<18 years of age) has not been investigated previously. Further knowledge of this area could allow more effective periodization of training, whilst also enabling coaches to design appropriate long-term athlete development models. This study investigated the within-season variation of fitness test performance in elite youth female soccer players. Methods: Nineteen elite youth female soccer players aged 11– 14 from two age group soccer teams (under 13 (U13) [n=10] and under 15 (U15) [n=9] corresponding to year of birth) participated in this study. A within-players design was used to investigate the variation of selected fitness parameters. The players completed a fitness testing protocol pre-, mid- and post-season, which tested 5 m acceleration, 20 m sprint, repeated-sprint (RSA) and change-ofdirectional (CoD) performance. Test-retest reliability for these tests was also investigated. Results: Substantial performance decrements were observed in 5 m acceleration, 20 m sprint and CoD performance at both midand post-season when compared to pre-season, with greatest decrements observed in the U13 players. For both groups the most substantial decrements were observed in CoD Performance (6.9 and 10.1% for U13 and U15s, respectively), and 5 m acceleration (8.0 and 3.6% for U13 and U15s, respectively) performance at the mid-season point. RSA was improved post-season in the U13s in comparison to pre- and mid- season. Test-retest reliability for the 20 m sprint, CoD and RSA tests was satisfactory (r>0.68), the 5 m acceleration test demonstrated poor reliability (r=0.24). Conclusion: In elite youth female soccer players, acceleration, sprint and CoD performance decreased over the course of a season, whilst RSA performance improved in U13 players. Coaches should consider the impact of physiological preparation on performance when working with youth female soccer players, implementing training interventions and recovery strategies accordingly to prevent reduced performance capacity during competition.
To examine the effect of low-volume sprint interval training (SIT) on the development (part 1) an... more To examine the effect of low-volume sprint interval training (SIT) on the development (part 1) and subsequent maintenance (part 2) of aerobic fitness in soccer players. In part 1, 23 players from the same semiprofessional team participated in a 2-wk SIT intervention (SIT, n = 14, age 25 ± 4 y, weight 77 ± 8 kg; control, n = 9, age 27 ± 6 y, weight 72 ± 10 kg). The SIT group performed 6 training sessions of 4-6 maximal 30-s sprints, in replacement of regular aerobic training. The control group continued with their regular training. After this 2-wk intervention, the SIT group was allocated to either intervention (n = 7, 1 SIT session/wk as replacement of regular aerobic training) or control (n = 7, regular aerobic training with no SIT sessions) for a 5-wk period (part 2). Pre and post measures were the YoYo Intermittent Recovery Test Level 1 (YYIRL1) and maximal oxygen uptake (VO2max). In part 1, the 2-week SIT intervention had a small beneficial effect on YYIRL1 (17%; 90% confidence limits ±11%), and VO2max (3.1%; ±5.0%) compared with control. In part 2, 1 SIT session/wk for 5 wk had a small beneficial effect on VO2max (4.2%; ±3.0%), with an unclear effect on YYIRL1 (8%; ±16%). Two weeks of SIT elicits small improvements in soccer players' high-intensity intermittent-running performance and VO2max, therefore representing a worthwhile replacement of regular aerobic training. The effectiveness of SIT for maintaining SIT-induced improvements in high-intensity intermittent running requires further research.
2010) 'Motion analysis of match-play in elite U12 to U16 age-group soccer players', Journal of Sp... more 2010) 'Motion analysis of match-play in elite U12 to U16 age-group soccer players', Journal of Sports Sciences,, First published on
International Journal of Sports Physiology and Performance, 2014
To quantify the effects of a 12-wk isolated core-training program on 50-m front-crawl swim time a... more To quantify the effects of a 12-wk isolated core-training program on 50-m front-crawl swim time and measures of core musculature functionally relevant to swimming. Twenty national-level junior swimmers (10 male and 10 female, 16 ± 1 y, 171 ± 5 cm, 63 ± 4 kg) participated in the study. Group allocation (intervention [n = 10], control [n = 10]) was based on 2 preexisting swim-training groups who were part of the same swimming club but trained in different groups. The intervention group completed the core training, incorporating exercises targeting the lumbopelvic complex and upper region extending to the scapula, 3 times/wk for 12 wk. While the training was performed in addition to the normal pool-based swimming program, the control group maintained their usual pool-based swimming program. The authors made probabilistic magnitude-based inferences about the effect of the core training on 50-m swim time and functionally relevant measures of core function. Compared with the control group, the core-training intervention group had a possibly large beneficial effect on 50-m swim time (-2.0%; 90% confidence interval -3.8 to -0.2%). Moreover, it showed small to moderate improvements on a timed prone-bridge test (9.0%; 2.1-16.4%) and asymmetric straight-arm pull-down test (23.1%; 13.7-33.4%), and there were moderate to large increases in peak EMG activity of core musculature during isolated tests of maximal voluntary contraction. This is the first study to demonstrate a clear beneficial effect of isolated core training on 50-m front-crawl swim performance.
To examine the within- and between-player variability of physical performance and player match lo... more To examine the within- and between-player variability of physical performance and player match loads in professional rugby union. A single cohort, observational study. Physical match performance data were collected from 28 male, professional, English Championship players over 15 competitive matches. Using microsensors, the variables selected for analysis were total distance, low-speed running distance, high-speed running distance, very high-speed running distance, total impacts, repeated high-intensity efforts, body load (PlayerLoad™), and low velocity (<7.2kmh(-1)) body load. Ratings of perceived exertion represented match internal loads. Variability was quantified using the coefficient of variation, with the meaningful interpretation of change in physical performance and match loads calculated using magnitude-based inferences. We found large between-match (within-player) variation for high-speed running distance (27.6%; ±90% confidence limits 6.9% [forwards], 20.1%; ±4.1% [backs]), very high-speed running distance (68%; ±19%, 34.1%; ±7.5%), total impacts (24.0%; ±5.9%, 36.4%; ±7.9%) and repeated high-intensity efforts (18.7%; ±4.4%, 39.5%; ±8.8%), with moderate variability for match ratings of perceived exertion (8.2%; ±1.8%, 10.8%; ±2.1%), body load (7.3%; ±1.7%, 10.0%; ±2.0%) and low velocity body load (8.9%; ±2.0%, 10.7%; ±2.1%). Threshold values for likely substantial between-match changes in high-intensity physical performance measures ranged from 21% to 76%, and were ∼10% for match ratings of perceived exertion, body load and low velocity body load. Within- and between-player variability of high-intensity activity in professional rugby union is large, yet ratings of perceived exertion, body load and low velocity body load appear more stable by comparison and may be interpreted with greater accuracy.
Intervention fidelity refers to the degree to which an experimental manipulation has been impleme... more Intervention fidelity refers to the degree to which an experimental manipulation has been implemented as intended, but simple, robust methods for quantifying fidelity have not been well documented. Therefore, we aim to illustrate a rigorous quantitative evaluation of intervention fidelity, using data collected during a high-intensity interval training intervention. Single-group measurement study. Seventeen adolescents (mean age ± standard deviation [SD] 14.0 ± 0.3 years) attended a 10-week high-intensity interval training intervention, comprising two exercise sessions per week. Sessions consisted of 4-7 45-s maximal effort repetitions, interspersed with 90-s rest. We collected heart rate data at 5-s intervals and recorded the peak heart rate for each repetition. The high-intensity exercise criterion was ≥ 90% of individual maximal heart rate. For each participant, we calculated the proportion of total exercise repetitions exceeding this threshold. A linear mixed model was applied to properly separate the variability in peak heart rate between- and within-subjects. Results are presented both as intention to treat (including missed sessions) and per protocol (only participants with 100% attendance; n=8). For intention to treat, the median (interquartile range) proportion of repetitions meeting the high-intensity criterion was 58% (42% to 68%). The mean peak heart rate was 85% of maximal, with a between-subject SD of 7.8 (95% confidence interval 5.4 to 11.3) percentage points and a within-subject SD of 15.1 (14.6 to 15.6) percentage points. For the per protocol analysis, the median proportion of high-intensity repetitions was 68% (47% to 86%). The mean peak heart rate was 91% of maximal, with between- and within-subject SDs of 3.1 (-1.3 to 4.6) and 3.4 (3.2 to 3.6) percentage points, respectively. Synthesising information on exercise session attendance and compliance (exercise intensity) quantifies the intervention dose and informs evaluations of treatment fidelity.
To perform an exploratory characterization of repeated sprint sequences (RSS) and repeated accele... more To perform an exploratory characterization of repeated sprint sequences (RSS) and repeated acceleration sequences (RAS) in top level soccer referees. 7 field and 7 assistant referees were monitored during 2007 America's Soccer Cup with GPS technology. Sprints of >18 km·h(-1) and accelerations of >1.5 m·s(-2) were considered as high intensity activities. RSS and RAS were defined as a minimum of 3 consecutive bouts interspersed with a maximum of 45 s. Field and assistant referees performed substantially more accelerations than sprints. Neither field nor assistant referees recorded any RSS. In contrast, total distance performing RAS amounted to ∼37% and ∼20% of the total distance covered by accelerations during the entire match for field and assistant referees, respectively. Only field referees exhibited fatigue-related reductions in RAS characteristics between halves. The results of the present study would appear to support the appropriateness of a repeated acceleration abil...
We were interested to read the recent article by Mugglestone et al. [9], which examined high-spee... more We were interested to read the recent article by Mugglestone et al. [9], which examined high-speed running performances of University soccer players during the early stages of each half in competitive match-play. The data is a welcome addition to a small body of work examining the within-match trends in soccer work rate, with particular reference to the half-time interval and its impact upon players' subsequent physical performances. In this letter we direct the authors to several relevant studies that were not considered in their article . We hope that by highlighting these research contributions to the authors and readership, interpretation of withinmatch analysis trends can be undertaken with necessary due care and caution.
The aim of the present study was to determine the between-match variability in soccer referees... more The aim of the present study was to determine the between-match variability in soccer referees' match performances. 1 269 individual match observations were undertaken on 59 referees (range 2-79 games per referee) officiating in the English Premier League and Championship from 2003/2004 to 2007/2008 using a computerised tracking system (Prozone (®), Leeds, England). Between-match coefficients of variation (CV) were calculated for all games and then compared between referee age and experience groups. High mean CVs were observed for high-speed running distance (25.9±10.1%), recovery time (32.7±13.8%), explosive sprints (34.3±16.6%), total number of sprints (54.0±20.7%) and number of match fouls (28±4.6%). Smaller CVs were observed for total distance covered (3.8±1.5%), top sprinting speed (5.6±10.9%), distance from the ball (4.2±1.9%) and the distance from fouls (9.9±4.3%). Variability in match activities was not influenced by referee age or experience. The present study's fin...
International journal of sports physiology and performance, 2011
Athlete case studies have often focused on the training outcome and not the training process. Con... more Athlete case studies have often focused on the training outcome and not the training process. Consequently, there is a dearth of information detailing longitudinal training protocols, yet it is the combined assessment of both outcome and process that enhances the interpretation of physical test data. We were provided with a unique opportunity to assess the training load, physical match performance, and physiological fitness of an elite soccer referee from the referee's final season before attaining full-time, professional status (2002) until the season when he refereed the 2010 UEFA Champions League and FIFA World Cup finals. An increased focus on on-field speed and gym-based strength training was observed toward the end of the study period and longitudinal match data showed a tendency for decreased total distances but an increased intensity of movements. Laboratory assessments demonstrated that VO2max remained stable (52.3 vs 50.8 mL·kg-1·min-1), whereas running speed at the la...
Repeated-sprint training appears to be an efficient and practical means for the simultaneous deve... more Repeated-sprint training appears to be an efficient and practical means for the simultaneous development of different components of fitness relevant to team sports. Our objective was to systematically review the literature and meta-analyse the effect of repeated-sprint training on a selection of field-based measures of athletic performance, i.e. counter-movement jump, 10 m sprint, 20 m sprint, 30 m sprint, repeated-sprint ability and high-intensity intermittent running performance. The SPORTDiscus, PubMed, MEDLINE and Web of Science databases were searched for original research articles. Search terms included 'repeated-sprint training', 'sprint training', 'aerobic endurance', 'repeated-sprint ability', 'counter-movement jump' and 'sprint…
International journal of sports physiology and performance, 2011
Soccer referees' physical match performances at the start of the second half (46-60 min) were... more Soccer referees' physical match performances at the start of the second half (46-60 min) were evaluated in relation to both the corresponding phase of the first half (0-15 min) and players' performances during the same match periods. Match analysis data were collected (Prozone, UK) from 12 soccer referees on 152 English Premier League matches during the 2008/09 soccer season. Physical match performance categories for referees and players were total distance, high-speed running distance (speed >5.5 m/s), and sprinting distance (>7.0 m/s). The referees' heart rate was recorded from the start of their warm-up to the end of the match. The referees' average distances (in meters) from the ball and fouls were also calculated. No substantial differences were observed in duration (16:42 ± 2:35 vs 16:27 ± 1:00 min) or intensity (107 ± 11 vs 106 ± 14 beats/ min) of the referees' preparation periods immediately before each half. Physical match performance was reduced d...
The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarbo... more The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarbo-xylato)-ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombina...
To investigate the application of differential ratings of perceived exertion for the examination ... more To investigate the application of differential ratings of perceived exertion for the examination of internal load during Australian Football League (AFL) matches. Single cohort, observational study. Using the centiMax rating of perceived exertion (RPE) scale, 26 professional AFL players provided ratings for match exertion (RPE-M), along with differential ratings for breathlessness (RPE-B), leg exertion (RPE-L), and technical demand (RPE-T) following 129 matches (5.0±1.6 matches per player). Global positioning satellite (GPS) and accelerometer measures were also collected. Data were analysed using magnitude-based inferences. RPE scores were 93.0±8.2 AU (RPE-M), 89.0±11.0 AU (RPE-B), 91.5±9.8 AU (RPE-L), and 87.0±10.0 AU (RPE-T). There was a most likely small difference between RPE-L and RPE-T (5.5%; ±90% confidence limits 1.9%), a likely small difference between RPE-L and RPE-B (3.5%; ±1.5%) and a possibly small difference between RPE-B and RPE-T (1.9%; ±1.9%). Within-player correlations between RPE and GPS measures were small for RPE-M (r=0.14-0.28), unclear to small for RPE-B (r=0.06-0.24) and unclear to moderate for RPE-L (r=0.06-0.37). Differential RPE's combined to explain 76% of the variance in RPE-M. For all RPE scores, within-player variability was moderate to high (typical error: 7.9-12.4%), and the thresholds for a likely between-match change were 8.8-13.7%. As differential RPE's represent distinct sensory inputs, the collection of these scores facilitate the interpretation of internal match loads and therefore represent a valuable addition to match data collection procedures. Moderate to high within-player variability should be considered when interpreting between-match changes in all RPE scores.
ABSTRACT Study Background: The within-season variation in fitness measures of elite youth female ... more ABSTRACT Study Background: The within-season variation in fitness measures of elite youth female soccer players (<18 years of age) has not been investigated previously. Further knowledge of this area could allow more effective periodization of training, whilst also enabling coaches to design appropriate long-term athlete development models. This study investigated the within-season variation of fitness test performance in elite youth female soccer players. Methods: Nineteen elite youth female soccer players aged 11– 14 from two age group soccer teams (under 13 (U13) [n=10] and under 15 (U15) [n=9] corresponding to year of birth) participated in this study. A within-players design was used to investigate the variation of selected fitness parameters. The players completed a fitness testing protocol pre-, mid- and post-season, which tested 5 m acceleration, 20 m sprint, repeated-sprint (RSA) and change-ofdirectional (CoD) performance. Test-retest reliability for these tests was also investigated. Results: Substantial performance decrements were observed in 5 m acceleration, 20 m sprint and CoD performance at both midand post-season when compared to pre-season, with greatest decrements observed in the U13 players. For both groups the most substantial decrements were observed in CoD Performance (6.9 and 10.1% for U13 and U15s, respectively), and 5 m acceleration (8.0 and 3.6% for U13 and U15s, respectively) performance at the mid-season point. RSA was improved post-season in the U13s in comparison to pre- and mid- season. Test-retest reliability for the 20 m sprint, CoD and RSA tests was satisfactory (r>0.68), the 5 m acceleration test demonstrated poor reliability (r=0.24). Conclusion: In elite youth female soccer players, acceleration, sprint and CoD performance decreased over the course of a season, whilst RSA performance improved in U13 players. Coaches should consider the impact of physiological preparation on performance when working with youth female soccer players, implementing training interventions and recovery strategies accordingly to prevent reduced performance capacity during competition.
To examine the effect of low-volume sprint interval training (SIT) on the development (part 1) an... more To examine the effect of low-volume sprint interval training (SIT) on the development (part 1) and subsequent maintenance (part 2) of aerobic fitness in soccer players. In part 1, 23 players from the same semiprofessional team participated in a 2-wk SIT intervention (SIT, n = 14, age 25 ± 4 y, weight 77 ± 8 kg; control, n = 9, age 27 ± 6 y, weight 72 ± 10 kg). The SIT group performed 6 training sessions of 4-6 maximal 30-s sprints, in replacement of regular aerobic training. The control group continued with their regular training. After this 2-wk intervention, the SIT group was allocated to either intervention (n = 7, 1 SIT session/wk as replacement of regular aerobic training) or control (n = 7, regular aerobic training with no SIT sessions) for a 5-wk period (part 2). Pre and post measures were the YoYo Intermittent Recovery Test Level 1 (YYIRL1) and maximal oxygen uptake (VO2max). In part 1, the 2-week SIT intervention had a small beneficial effect on YYIRL1 (17%; 90% confidence limits ±11%), and VO2max (3.1%; ±5.0%) compared with control. In part 2, 1 SIT session/wk for 5 wk had a small beneficial effect on VO2max (4.2%; ±3.0%), with an unclear effect on YYIRL1 (8%; ±16%). Two weeks of SIT elicits small improvements in soccer players' high-intensity intermittent-running performance and VO2max, therefore representing a worthwhile replacement of regular aerobic training. The effectiveness of SIT for maintaining SIT-induced improvements in high-intensity intermittent running requires further research.
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