Soccer referees&a... 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 during the initial phase of the second half when compared with the first half in both referees (effect sizes-standardized mean differences-0.19 to 0.73) and players (effect sizes 0.20 to 1.01). The degree of the decreased performance was consistent between referees and players for total distance (4.7 m), high-speed running (1.5 m), and sprinting (1.1 m). The referees were closer to the ball (effect size 0.52) during the opening phase the second half. Given the similarity in the referees' preparation periods, it may be that the reduced physical match performances observed in soccer referees during the opening stages of the second half are a consequence of a slower tempo of play.
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.
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...
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.
Journal of Strength and Conditioning Research, 2015
The effectiveness of fundamental movement training interventions in adolescents is not fully unde... more The effectiveness of fundamental movement training interventions in adolescents is not fully understood. The Functional Movement Screen (FMS) may provide means of evaluating the effectiveness of such programs alongside traditional tests of physiological performance. Twenty-two children completed the FMS, plank, side plank, sit and reach, and multistage fitness test. Participants were pair matched by total FMS score and assigned to control or intervention. The intervention group received a weekly 4 × 30-minute training sessions with an emphasis on movement quality, whereas the control group was involved in generic multisport activity. A smallest worthwhile effect of 0.2 between-participant SDs was set a priori for all measures except total FMS score for which a change of 1 unit was chosen. When compared with the control, our intervention had a likely trivial effect for FMS score (0.2 Arbitrary Units [AU], 90% confidence limits ±1.2 AU), a very likely small beneficial effect for plank score (87 ± 55%), but a possibly small harmful effect for side plank score (-22 ± 49%). A likely trivial effect was observed for the sit and reach test (0.3 ± 15%), whereas the effect of the training intervention on predicted (Equation is included in full-text article.)was unclear (-0.3 ± 11%). Unexpectedly, generic multisport activity enhanced both side plank and sit and reach test performances in the control group. These results demonstrated that short-term interventions might affect specific isolated components of fitness but not FMS performance.
Journal of Strength and Conditioning Research, 2011
Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and ... more Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and semiautomated video-based performance data during elite soccer match play. J Strength Cond Res 25 : 2334-2336, 2011-In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone Ò [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; .4.0 mÁs -1 ) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD GPS: 1,755.4 6 245.4 m; PZ: 1,631.3 6 239.5 m; p , 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 6 24.0 m; GPS: 20.3 6 15.8 m; HIR: PZ, 368.1 6 129.8 m; GPS: 317.0 6 92.5 m; p , 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.
Journal of Strength and Conditioning Research, 2012
The aim of our study was to investigate the effect of a short, practical, 2-phase warm-up on repe... more The aim of our study was to investigate the effect of a short, practical, 2-phase warm-up on repeated sprint performance when compared with more traditional warm-up protocols that contain stretching activities. Eleven subelite male soccer players completed a warm-up protocol that commenced with 5 minutes jogging at approximately 65% of maximal heart rate, followed by no stretching, static stretching, or dynamic stretching and finishing with a task-specific high-intensity activity. Using a crossover design, the 3 warm-up protocols were performed in a counterbalanced order with at least 48 hours between sessions. Repeated sprint performance was measured using a repeated sprint test that consisted of 6 × 40-m maximal sprints interspersed with a 20-second recovery. There were trivial differences in mean sprint time (0.2%) and posttest blood lactate (3.1%) between the 2-phase warm-up and the 3-phase warm-up that included dynamic stretching, whereas the short warm-up had a possibly detrimental effect on fastest sprint time (0.7%). Fastest (-1.1%) and mean (-1.2%) sprint times were quicker and posttest blood lactates were higher (13.2%) after the 2-phase warm-up when compared with the 3-phase warm-up that included static stretching. Although it is not harmful to complete a traditional 3-phase warm-up that includes dynamic stretching, it appears practical for athletes preparing for activities dependent on repeated sprint ability to complete a 2-phase warm-up consisting of a cardiovascular and specific high-intensity activity.
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
Objectives: To re-examine the work-rate of soccer players immediately after a passive half-time i... more Objectives: To re-examine the work-rate of soccer players immediately after a passive half-time interval with an alternative approach to data reduction and statistical contrasts. Design: Time-motion analysis data (5 Hz global positioning system), were collected from 20 elite youth players (age: 17 ± 1 years) during 21 competitive league fixtures (5 ± 3 matches per player). Methods: Physical performances were categorised into total distance covered, total low-speed running (0-14.9 km h −1 ) and total high-speed running (15.0-35.0 km h −1 ). These dependent variables were subsequently time averaged into pre-determined periods of 5-, 15-and 45-min duration, and expressed in relative (m min −1 ) terms to allow direct comparisons between match periods of different lengths. During the 15-min half-time interval players were passive (seated rest). Results: There was a large reduction in relative total distance covered (effect size -standardised mean difference -1.85), low-speed running (effect size −1.74) and high-speed running (effect size −1.37) during the opening 5-min phase of the second half (46-50 min) when compared to the first half mean (0-45 min). When comparing the 51-55 and 56-60-min periods, effect sizes were trivial for relative total distance covered (effect size −0.13; −0.04), low-speed running (effect size −0.10; −0.11) and small/trivial for high-speed running (−0.39; 0.11). Conclusions: Using a more robust analytical approach, the findings of this study support and extend previous research demonstrating that players work-rate was markedly lower in the first 5-min after a passive half-time interval, although we observed this phenomenon to be transient in nature. Time-motion analysts might re-consider their data reduction methods and comparators to distinguish within-match player work-rate trends.
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.
Soccer referees&a... 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 during the initial phase of the second half when compared with the first half in both referees (effect sizes-standardized mean differences-0.19 to 0.73) and players (effect sizes 0.20 to 1.01). The degree of the decreased performance was consistent between referees and players for total distance (4.7 m), high-speed running (1.5 m), and sprinting (1.1 m). The referees were closer to the ball (effect size 0.52) during the opening phase the second half. Given the similarity in the referees' preparation periods, it may be that the reduced physical match performances observed in soccer referees during the opening stages of the second half are a consequence of a slower tempo of play.
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.
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...
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.
Journal of Strength and Conditioning Research, 2015
The effectiveness of fundamental movement training interventions in adolescents is not fully unde... more The effectiveness of fundamental movement training interventions in adolescents is not fully understood. The Functional Movement Screen (FMS) may provide means of evaluating the effectiveness of such programs alongside traditional tests of physiological performance. Twenty-two children completed the FMS, plank, side plank, sit and reach, and multistage fitness test. Participants were pair matched by total FMS score and assigned to control or intervention. The intervention group received a weekly 4 × 30-minute training sessions with an emphasis on movement quality, whereas the control group was involved in generic multisport activity. A smallest worthwhile effect of 0.2 between-participant SDs was set a priori for all measures except total FMS score for which a change of 1 unit was chosen. When compared with the control, our intervention had a likely trivial effect for FMS score (0.2 Arbitrary Units [AU], 90% confidence limits ±1.2 AU), a very likely small beneficial effect for plank score (87 ± 55%), but a possibly small harmful effect for side plank score (-22 ± 49%). A likely trivial effect was observed for the sit and reach test (0.3 ± 15%), whereas the effect of the training intervention on predicted (Equation is included in full-text article.)was unclear (-0.3 ± 11%). Unexpectedly, generic multisport activity enhanced both side plank and sit and reach test performances in the control group. These results demonstrated that short-term interventions might affect specific isolated components of fitness but not FMS performance.
Journal of Strength and Conditioning Research, 2011
Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and ... more Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and semiautomated video-based performance data during elite soccer match play. J Strength Cond Res 25 : 2334-2336, 2011-In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone Ò [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; .4.0 mÁs -1 ) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD GPS: 1,755.4 6 245.4 m; PZ: 1,631.3 6 239.5 m; p , 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 6 24.0 m; GPS: 20.3 6 15.8 m; HIR: PZ, 368.1 6 129.8 m; GPS: 317.0 6 92.5 m; p , 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.
Journal of Strength and Conditioning Research, 2012
The aim of our study was to investigate the effect of a short, practical, 2-phase warm-up on repe... more The aim of our study was to investigate the effect of a short, practical, 2-phase warm-up on repeated sprint performance when compared with more traditional warm-up protocols that contain stretching activities. Eleven subelite male soccer players completed a warm-up protocol that commenced with 5 minutes jogging at approximately 65% of maximal heart rate, followed by no stretching, static stretching, or dynamic stretching and finishing with a task-specific high-intensity activity. Using a crossover design, the 3 warm-up protocols were performed in a counterbalanced order with at least 48 hours between sessions. Repeated sprint performance was measured using a repeated sprint test that consisted of 6 × 40-m maximal sprints interspersed with a 20-second recovery. There were trivial differences in mean sprint time (0.2%) and posttest blood lactate (3.1%) between the 2-phase warm-up and the 3-phase warm-up that included dynamic stretching, whereas the short warm-up had a possibly detrimental effect on fastest sprint time (0.7%). Fastest (-1.1%) and mean (-1.2%) sprint times were quicker and posttest blood lactates were higher (13.2%) after the 2-phase warm-up when compared with the 3-phase warm-up that included static stretching. Although it is not harmful to complete a traditional 3-phase warm-up that includes dynamic stretching, it appears practical for athletes preparing for activities dependent on repeated sprint ability to complete a 2-phase warm-up consisting of a cardiovascular and specific high-intensity activity.
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
Objectives: To re-examine the work-rate of soccer players immediately after a passive half-time i... more Objectives: To re-examine the work-rate of soccer players immediately after a passive half-time interval with an alternative approach to data reduction and statistical contrasts. Design: Time-motion analysis data (5 Hz global positioning system), were collected from 20 elite youth players (age: 17 ± 1 years) during 21 competitive league fixtures (5 ± 3 matches per player). Methods: Physical performances were categorised into total distance covered, total low-speed running (0-14.9 km h −1 ) and total high-speed running (15.0-35.0 km h −1 ). These dependent variables were subsequently time averaged into pre-determined periods of 5-, 15-and 45-min duration, and expressed in relative (m min −1 ) terms to allow direct comparisons between match periods of different lengths. During the 15-min half-time interval players were passive (seated rest). Results: There was a large reduction in relative total distance covered (effect size -standardised mean difference -1.85), low-speed running (effect size −1.74) and high-speed running (effect size −1.37) during the opening 5-min phase of the second half (46-50 min) when compared to the first half mean (0-45 min). When comparing the 51-55 and 56-60-min periods, effect sizes were trivial for relative total distance covered (effect size −0.13; −0.04), low-speed running (effect size −0.10; −0.11) and small/trivial for high-speed running (−0.39; 0.11). Conclusions: Using a more robust analytical approach, the findings of this study support and extend previous research demonstrating that players work-rate was markedly lower in the first 5-min after a passive half-time interval, although we observed this phenomenon to be transient in nature. Time-motion analysts might re-consider their data reduction methods and comparators to distinguish within-match player work-rate trends.
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.
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Papers by M. Portas