Geert Savelsbergh - Academia.edu (original) (raw)

Papers by Geert Savelsbergh

Frontiers in Sports and Active Living

Perceptual–cognitive skills are found to be important factors for soccer players. The aim of this... more Perceptual–cognitive skills are found to be important factors for soccer players. The aim of this study was, therefore, to find within-group differences for game insight in an elite group of youth soccer players by means of a Game Insight inDicator (GID). In addition, the prospective value of perceptual–cognitive skills was examined by following the trajectory of the participants. The GID consisted of film clips that show game situations. The task of the players was to predict the trajectory and destination of the ball and move toward the correct position to receive the pass of a teammate. The film clips stopped 80 ms before, at, and 80 ms after the football contact of a teammate. We also sought to validate the GID against game performance. Participants were talented soccer players 11–13 years old and playing at the elite level for their age. Based on eight independent elite-coach judgments, two groups were created: highly talented players (HT) and less talented players (LT). The co...

International Journal of Sports Physiology and Performance

Purpose: To determine the test–retest reliability of the recently developed Hip Load metric, eval... more Purpose: To determine the test–retest reliability of the recently developed Hip Load metric, evaluate its construct validity, and assess the differences with Playerload during football-specific short-distance shuttle runs. Methods: Eleven amateur football players participated in 2 identical experimental sessions. Each session included 3 different shuttle runs that were performed at 2 pace-controlled running intensities. The runs consisted of only running, running combined with kicks, and running combined with jumps. Cumulative Playerload and Hip Loads of the preferred and nonpreferred kicking leg were collected for each shuttle run. Test–retest reliability was determined using intraclass correlations, coefficients of variation, and Bland–Altman analyses. To compare the load metrics with each other, they were normalized to their respective values obtained during a 54-m run at 9 km/h. Sensitivity of each load metric to running intensity, kicks, and jumps was assessed using separate li...

The impact of cognitive training activity (the Football IntelliGym training system) on football p... more The impact of cognitive training activity (the Football IntelliGym training system) on football performance has been tested within two elite football academies: PSV Eindhoven and AZ Alkmaar. The study compared the performance of an experimental group (IntelliGym) and a control group (placebo) based on an objective football performance metrics, using the Notation Analysis System (an objective performance analysis, developed by VU University), before and after cognitive intervention. In all tested groups, the study has found significantly better results in performance of the experimental group compared to the control group.

Annals of Human Biology, 2020

Sensors, 2020

Inertial sensor-based measurements of lower body kinematics in football players may improve physi... more Inertial sensor-based measurements of lower body kinematics in football players may improve physical load estimates during training sessions and matches. However, the validity of inertial-based motion analysis systems is specific to both the type of movement and the intensity at which movements are executed. Importantly, such a system should be relatively simple, so it can easily be used in daily practice. This paper introduces an easy-to-use inertial-based motion analysis system and evaluates its validity using an optoelectronic motion analysis system as a gold standard. The system was validated in 11 football players for six different football specific movements that were executed at low, medium, and maximal intensity. Across all movements and intensities, the root mean square differences (means ± SD) for knee and hip flexion/extension angles were 5.3° ± 3.4° and 8.0° ± 3.5°, respectively, illustrating good validity with the gold standard. In addition, mean absolute flexion/extens...

International Journal of Sports Science & Coaching, 2020

The aim of the study was to investigate whether performance of children can be improved by traini... more The aim of the study was to investigate whether performance of children can be improved by training with modified equipment that challenges movement execution. For that purpose, young field hockey players practiced with a modified and a regular hockey ball. The modified hockey ball enforces more variable movement execution during practice by rolling less predictably than a regular hockey ball and, thus, challenges the players’ stick–ball control. Two groups of 7- to 9-year old children, with 0 to 4 years of experience, participated in a crossover-design, in which they either received four training sessions with the modified ball followed by four training sessions with the regular ball or vice versa. In a pretest, intermediate test (i.e. following the first four training sessions) and a posttest, the participants dribbled an obstacle parcours with a regular ball. Results show that practice with the modified ball led to greater performance improvement than the intervention with the re...

Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte, 2019

BMJ Open Sport & Exercise Medicine, 2019

AimWe investigated the extent and characteristics of injuries in contemporary dance students.Meth... more AimWe investigated the extent and characteristics of injuries in contemporary dance students.MethodsDuring one academic year, 134 students of Bachelor dance and Bachelor dance teacher from Codarts University of the Arts (Rotterdam, the Netherlands) were prospectively monitored monthly, using the Performing Artist and Athlete Health Monitor which includes the Oslo Sports Trauma Research Centre Questionnaire on Health Problems.Results130 students were included in the analyses. The response rate of monthly completed questionnaires was 80%. During the academic year, 97% of students reported at least one injury, mental complaint or other health problem. The 1-year injury incidence proportion was 81%. Of these injured students, 58% were substantially injured (ie, problems leading to moderate or severe reductions in training volume or performance or complete inability to participate in activities). The monthly injury proportion (all injuries) ranged from 23% to 43% and for substantial inju...

Human Movement Science, 2018

Science and Medicine in Football, 2017

Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte, 2016

International Journal of Sports Science & Coaching, 2017

The objective of this study was to compose an objective and detailed notational analysis system f... more The objective of this study was to compose an objective and detailed notational analysis system for 3 vs. 2 + GK small-sided soccer games, in which three roles are examined: attacker with ball, attacker without ball and defender. The actions and the outcome of the actions were registered for each player and in each role. Players earn points for each action and outcome according to an a priori determined scheme. Performance scores for each role are calculated as the average number of points a participant earns per trial. This notation system was tested on 19 highly talented female soccer players and validity and reliability of the system were determined. In addition, practical applications were discussed and the most important items of the notation system were determined and using only these items, a simplified notation system was proposed. The notation system has high ecological validity and can discriminate the high and low categorized players, but further development is necessary ...

Movement & Sport Sciences - Science & Motricité, 2019

The purpose of the current paper is to advocate that the athletic skills model (ASM) serves as a ... more The purpose of the current paper is to advocate that the athletic skills model (ASM) serves as a suitable framework to structure (developmental) movement programs to enhance physical literacy as a foundation for expertise. Taking the non-linear developmental trajectories into account (including the possibility to follow the linear developmental pathway), the ASM applies three “roads” to reach this goal, that is, the concentric approach, creating challenging environments, and exploiting transfer. Each of these separately or in combination with each other will increase the level of physical literacy, that is creating more functional variation leading to an increasement of possibilities for adaptation of those involved (athletes, PE teachers, and coaches). ASM seeks a life-long physical activity participation and to maintain a balance between performance, fitness and health for the recreational as well for the disable and able (elite) athlete.

Frontiers in Human Neuroscience, 2021

The key to action control is one’s ability to adequately predict the consequences of one’s action... more The key to action control is one’s ability to adequately predict the consequences of one’s actions. Predictive processing theories assume that forward models enable rapid “preplay” to assess the match between predicted and intended action effects. Here we propose the novel hypothesis that “reading” another’s action intentions requires a rich forward model of that agent’s action. Such a forward model can be obtained and enriched through learning by either practice or simulation. Based on this notion, we ran a series of studies on soccer goalkeepers and novices, who predicted the intended direction of penalties being kicked at them in a computerized penalty-reading task. In line with hypotheses, extensive practice in penalty kicking improved performance in penalty reading among goalkeepers who had extensive prior experience in penalty blocking but not in penalty kicking. A robust benefit in penalty reading did not result from practice in kinesthetic motor imagery of penalty kicking in...

Scandinavian Journal of Medicine & Science in Sports

Funding information This study is funded by RAAK-PRO/SIA ref. 2014−01−114PRO Adequate gross motor... more Funding information This study is funded by RAAK-PRO/SIA ref. 2014−01−114PRO Adequate gross motor skills are an essential aspect of a child's healthy development. Where physical education (PE) is part of the primary school curriculum, a strong curriculum-based emphasis on evaluation and support of motor skill development in PE is apparent. Monitoring motor development is then a task for the PE teacher. To fulfill this task, teachers need adequate tools. The 4-Skills Scan is a quick and easily manageable gross motor skill instrument; however, its validity has never been assessed. Therefore, the purpose of this study was to assess the construct and concurrent validity of both 4-Skills Scans (version 2007 and version 2015). A total of 212 primary school children (6-12 years old) was requested to participate in both versions of the 4-Skills Scan. For assessing construct validity, children covered an obstacle course with video recordings for observation by an expert panel. For concurrent validity, a comparison was made with the M-ABC-2, by calculating Pearson correlations. Multivariable linear regression analyses were performed to determine the contribution of each subscale to the construct of gross motor skills, according to the M-ABC-2 and the expert panel. Correlations between the 4-Skills Scans and expert valuations were moderate, with coefficients of .47 (version 2007) and .46 (version 2015). Correlations between the 4-Skills Scans and the M-ABC-2 (gross) were moderate (.56) for version 2007 and high (.64) for version 2015. It is concluded that both versions of the 4-Skills Scans are satisfactory valid instruments for assessing gross motor skills during PE lessons. K E Y W O R D S motor skill assessment, physical education, primary school children, psychometrics, validity This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Down syndrome (DS) presents a unique etiology that affects many areas of development. Of specific... more Down syndrome (DS) presents a unique etiology that affects many areas of development. Of specific concern are the factors which may result in a delayed development of, for instance, fundamental motor patterns, physical fitness and the

International Journal of Sports Science & Coaching, 2020

Visual gaze behaviour, and in particular Quiet Eye (QE), have been found to be important in aimin... more Visual gaze behaviour, and in particular Quiet Eye (QE), have been found to be important in aiming tasks in multiple sports. The aim of this study is to provide insight into the characteristics of gaze behaviour in a moving condition, that is of football players during the run-up and kick of free kicks. Fourteen skilled youth players performed a set of free-kick trials while their eyes were being tracked. Two QE periods have been determined prior to a critical phase of the kick: QE Target and QE Ball. For the scored trials both the QE Target (M = 886 ms SE = 78 ms) and QE Ball (M = 627 ms SE = 52 ms) duration were significantly longer than in the missed trials, QE Target (M = 488 ms SE = 45 ms) and QE Ball (M = 513 ms SE = 80 ms). The analysis of the number of fixations suggests that one fixation on a target is the optimum, and more (2-3x) or no fixations resulted in less accurate shooting. These results provide insight into the characteristics of football shooting that can be incor...

Motor Control, 2005

The aim of the present study was to examine the effects of balance training with visual feedback ... more The aim of the present study was to examine the effects of balance training with visual feedback on stance and gait in school-age children with hemiplegic cerebral palsy. Ten participants between 5 and 11 years of age were assigned to either the training or the control group according to an aged-stratified randomization. The training corresponded to three sessions per week during six weeks. Stance and gait parameters, based on force plate data, were assessed three times in both groups: (a) at the beginning of the study (before training); (b) after six weeks; (c) after ten weeks. Spatial and temporal parameters were calculated. The results for stance showed that the training improved the performances on the tasks that were trained. More interesting, the results for gait showed that the walking pattern became more symmetrical after the training.

Frontiers in Sports and Active Living

Perceptual–cognitive skills are found to be important factors for soccer players. The aim of this... more Perceptual–cognitive skills are found to be important factors for soccer players. The aim of this study was, therefore, to find within-group differences for game insight in an elite group of youth soccer players by means of a Game Insight inDicator (GID). In addition, the prospective value of perceptual–cognitive skills was examined by following the trajectory of the participants. The GID consisted of film clips that show game situations. The task of the players was to predict the trajectory and destination of the ball and move toward the correct position to receive the pass of a teammate. The film clips stopped 80 ms before, at, and 80 ms after the football contact of a teammate. We also sought to validate the GID against game performance. Participants were talented soccer players 11–13 years old and playing at the elite level for their age. Based on eight independent elite-coach judgments, two groups were created: highly talented players (HT) and less talented players (LT). The co...

International Journal of Sports Physiology and Performance

Purpose: To determine the test–retest reliability of the recently developed Hip Load metric, eval... more Purpose: To determine the test–retest reliability of the recently developed Hip Load metric, evaluate its construct validity, and assess the differences with Playerload during football-specific short-distance shuttle runs. Methods: Eleven amateur football players participated in 2 identical experimental sessions. Each session included 3 different shuttle runs that were performed at 2 pace-controlled running intensities. The runs consisted of only running, running combined with kicks, and running combined with jumps. Cumulative Playerload and Hip Loads of the preferred and nonpreferred kicking leg were collected for each shuttle run. Test–retest reliability was determined using intraclass correlations, coefficients of variation, and Bland–Altman analyses. To compare the load metrics with each other, they were normalized to their respective values obtained during a 54-m run at 9 km/h. Sensitivity of each load metric to running intensity, kicks, and jumps was assessed using separate li...

The impact of cognitive training activity (the Football IntelliGym training system) on football p... more The impact of cognitive training activity (the Football IntelliGym training system) on football performance has been tested within two elite football academies: PSV Eindhoven and AZ Alkmaar. The study compared the performance of an experimental group (IntelliGym) and a control group (placebo) based on an objective football performance metrics, using the Notation Analysis System (an objective performance analysis, developed by VU University), before and after cognitive intervention. In all tested groups, the study has found significantly better results in performance of the experimental group compared to the control group.

Annals of Human Biology, 2020

Sensors, 2020

Inertial sensor-based measurements of lower body kinematics in football players may improve physi... more Inertial sensor-based measurements of lower body kinematics in football players may improve physical load estimates during training sessions and matches. However, the validity of inertial-based motion analysis systems is specific to both the type of movement and the intensity at which movements are executed. Importantly, such a system should be relatively simple, so it can easily be used in daily practice. This paper introduces an easy-to-use inertial-based motion analysis system and evaluates its validity using an optoelectronic motion analysis system as a gold standard. The system was validated in 11 football players for six different football specific movements that were executed at low, medium, and maximal intensity. Across all movements and intensities, the root mean square differences (means ± SD) for knee and hip flexion/extension angles were 5.3° ± 3.4° and 8.0° ± 3.5°, respectively, illustrating good validity with the gold standard. In addition, mean absolute flexion/extens...

International Journal of Sports Science & Coaching, 2020

The aim of the study was to investigate whether performance of children can be improved by traini... more The aim of the study was to investigate whether performance of children can be improved by training with modified equipment that challenges movement execution. For that purpose, young field hockey players practiced with a modified and a regular hockey ball. The modified hockey ball enforces more variable movement execution during practice by rolling less predictably than a regular hockey ball and, thus, challenges the players’ stick–ball control. Two groups of 7- to 9-year old children, with 0 to 4 years of experience, participated in a crossover-design, in which they either received four training sessions with the modified ball followed by four training sessions with the regular ball or vice versa. In a pretest, intermediate test (i.e. following the first four training sessions) and a posttest, the participants dribbled an obstacle parcours with a regular ball. Results show that practice with the modified ball led to greater performance improvement than the intervention with the re...

Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte, 2019

BMJ Open Sport & Exercise Medicine, 2019

AimWe investigated the extent and characteristics of injuries in contemporary dance students.Meth... more AimWe investigated the extent and characteristics of injuries in contemporary dance students.MethodsDuring one academic year, 134 students of Bachelor dance and Bachelor dance teacher from Codarts University of the Arts (Rotterdam, the Netherlands) were prospectively monitored monthly, using the Performing Artist and Athlete Health Monitor which includes the Oslo Sports Trauma Research Centre Questionnaire on Health Problems.Results130 students were included in the analyses. The response rate of monthly completed questionnaires was 80%. During the academic year, 97% of students reported at least one injury, mental complaint or other health problem. The 1-year injury incidence proportion was 81%. Of these injured students, 58% were substantially injured (ie, problems leading to moderate or severe reductions in training volume or performance or complete inability to participate in activities). The monthly injury proportion (all injuries) ranged from 23% to 43% and for substantial inju...

Human Movement Science, 2018

Science and Medicine in Football, 2017

Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte, 2016

International Journal of Sports Science & Coaching, 2017

The objective of this study was to compose an objective and detailed notational analysis system f... more The objective of this study was to compose an objective and detailed notational analysis system for 3 vs. 2 + GK small-sided soccer games, in which three roles are examined: attacker with ball, attacker without ball and defender. The actions and the outcome of the actions were registered for each player and in each role. Players earn points for each action and outcome according to an a priori determined scheme. Performance scores for each role are calculated as the average number of points a participant earns per trial. This notation system was tested on 19 highly talented female soccer players and validity and reliability of the system were determined. In addition, practical applications were discussed and the most important items of the notation system were determined and using only these items, a simplified notation system was proposed. The notation system has high ecological validity and can discriminate the high and low categorized players, but further development is necessary ...

Movement & Sport Sciences - Science & Motricité, 2019

The purpose of the current paper is to advocate that the athletic skills model (ASM) serves as a ... more The purpose of the current paper is to advocate that the athletic skills model (ASM) serves as a suitable framework to structure (developmental) movement programs to enhance physical literacy as a foundation for expertise. Taking the non-linear developmental trajectories into account (including the possibility to follow the linear developmental pathway), the ASM applies three “roads” to reach this goal, that is, the concentric approach, creating challenging environments, and exploiting transfer. Each of these separately or in combination with each other will increase the level of physical literacy, that is creating more functional variation leading to an increasement of possibilities for adaptation of those involved (athletes, PE teachers, and coaches). ASM seeks a life-long physical activity participation and to maintain a balance between performance, fitness and health for the recreational as well for the disable and able (elite) athlete.

Frontiers in Human Neuroscience, 2021

The key to action control is one’s ability to adequately predict the consequences of one’s action... more The key to action control is one’s ability to adequately predict the consequences of one’s actions. Predictive processing theories assume that forward models enable rapid “preplay” to assess the match between predicted and intended action effects. Here we propose the novel hypothesis that “reading” another’s action intentions requires a rich forward model of that agent’s action. Such a forward model can be obtained and enriched through learning by either practice or simulation. Based on this notion, we ran a series of studies on soccer goalkeepers and novices, who predicted the intended direction of penalties being kicked at them in a computerized penalty-reading task. In line with hypotheses, extensive practice in penalty kicking improved performance in penalty reading among goalkeepers who had extensive prior experience in penalty blocking but not in penalty kicking. A robust benefit in penalty reading did not result from practice in kinesthetic motor imagery of penalty kicking in...

Scandinavian Journal of Medicine & Science in Sports

Funding information This study is funded by RAAK-PRO/SIA ref. 2014−01−114PRO Adequate gross motor... more Funding information This study is funded by RAAK-PRO/SIA ref. 2014−01−114PRO Adequate gross motor skills are an essential aspect of a child's healthy development. Where physical education (PE) is part of the primary school curriculum, a strong curriculum-based emphasis on evaluation and support of motor skill development in PE is apparent. Monitoring motor development is then a task for the PE teacher. To fulfill this task, teachers need adequate tools. The 4-Skills Scan is a quick and easily manageable gross motor skill instrument; however, its validity has never been assessed. Therefore, the purpose of this study was to assess the construct and concurrent validity of both 4-Skills Scans (version 2007 and version 2015). A total of 212 primary school children (6-12 years old) was requested to participate in both versions of the 4-Skills Scan. For assessing construct validity, children covered an obstacle course with video recordings for observation by an expert panel. For concurrent validity, a comparison was made with the M-ABC-2, by calculating Pearson correlations. Multivariable linear regression analyses were performed to determine the contribution of each subscale to the construct of gross motor skills, according to the M-ABC-2 and the expert panel. Correlations between the 4-Skills Scans and expert valuations were moderate, with coefficients of .47 (version 2007) and .46 (version 2015). Correlations between the 4-Skills Scans and the M-ABC-2 (gross) were moderate (.56) for version 2007 and high (.64) for version 2015. It is concluded that both versions of the 4-Skills Scans are satisfactory valid instruments for assessing gross motor skills during PE lessons. K E Y W O R D S motor skill assessment, physical education, primary school children, psychometrics, validity This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Down syndrome (DS) presents a unique etiology that affects many areas of development. Of specific... more Down syndrome (DS) presents a unique etiology that affects many areas of development. Of specific concern are the factors which may result in a delayed development of, for instance, fundamental motor patterns, physical fitness and the

International Journal of Sports Science & Coaching, 2020

Visual gaze behaviour, and in particular Quiet Eye (QE), have been found to be important in aimin... more Visual gaze behaviour, and in particular Quiet Eye (QE), have been found to be important in aiming tasks in multiple sports. The aim of this study is to provide insight into the characteristics of gaze behaviour in a moving condition, that is of football players during the run-up and kick of free kicks. Fourteen skilled youth players performed a set of free-kick trials while their eyes were being tracked. Two QE periods have been determined prior to a critical phase of the kick: QE Target and QE Ball. For the scored trials both the QE Target (M = 886 ms SE = 78 ms) and QE Ball (M = 627 ms SE = 52 ms) duration were significantly longer than in the missed trials, QE Target (M = 488 ms SE = 45 ms) and QE Ball (M = 513 ms SE = 80 ms). The analysis of the number of fixations suggests that one fixation on a target is the optimum, and more (2-3x) or no fixations resulted in less accurate shooting. These results provide insight into the characteristics of football shooting that can be incor...

Motor Control, 2005

The aim of the present study was to examine the effects of balance training with visual feedback ... more The aim of the present study was to examine the effects of balance training with visual feedback on stance and gait in school-age children with hemiplegic cerebral palsy. Ten participants between 5 and 11 years of age were assigned to either the training or the control group according to an aged-stratified randomization. The training corresponded to three sessions per week during six weeks. Stance and gait parameters, based on force plate data, were assessed three times in both groups: (a) at the beginning of the study (before training); (b) after six weeks; (c) after ten weeks. Spatial and temporal parameters were calculated. The results for stance showed that the training improved the performances on the tasks that were trained. More interesting, the results for gait showed that the walking pattern became more symmetrical after the training.