Whilst smaller pitches have become the norm in junior football, they may still be too large for certain ages and levels of skill. To date there has been no research into the relationships between size of the pitch and the technical kicking ability (distance and accuracy) of young players (8 - 14 years of age). The purpose of this investigation was to examine variables that influence actual kicking distance and accuracy and also to measure what differences in play behaviour (passing and dribbling) emerge from self-selected changes in pitch size for different age groups (9 and 10 years of age). Data were collected on 120 (N=120) junior football players: Playing experience (M=2.85 years, SD=2.56), Height (M=1.44 m, SD=1.08), Weight (M=37.8 kg, SD=7.69), Lengths of lower limbs (knee/ankle: M=35.54 cm, SD=4.27; hip/knee: M=35.54 cm, SD=5.25), Step lengths (M=37.66 cm, SD=8.693), Estimated kicking distance (M=31.13 m, SD=16.63). Participants performed a series of three kicks along the ground, using the inside of the foot, and aiming for a target (25 m away). The distance (M=18.04 m; SD=6.56) and accuracy (M=8.32 m; SD=4.38) of each kick were measured. The children (9 and 10 years of age) were then assigned to teams and asked to construct a small-sided game on two different pitch sizes. The first pitch size used was the recommended regulation size. The second pitch size was self-selected by the players. Any changes to the playing dimensions (e.g., width of the pitch) and playing behaviours (e.g., total number of passes, dribbling) were measured and analysed. Kicking distance is best predicted by the player’s height (20.0%, P < 0.000), or a combination of the player’s height and estimated kicking distance (30.0%, P = 0.002). Kicking accuracy can be attributed to the influence of the player’s step lengths (8.1%, P = 0.016) and both their step lengths and estimated kicking distance (15.1%, P = 0.020). Furthermore, our findings demonstrate that the increase in pitch size (18.5% and 25%) resulted in a greater amount of dribbling (63% and 33%) and passing (12%). In general, our results support the idea that young children in New Zealand should be playing on a pitch and at a skill level which matches their football abilities. Grouping young players on a pitch according to their physical (e.g., height) and technical kicking ability (e.g., distance, accuracy) instead of their chronological age, seems to be the key factor to any other set of proposals. The findings of this thesis have important messages that could enhance the effectiveness of coaching, competitive game-play (pitch sizes) and consequently performance at all junior levels of football in New Zealand. Further research should manipulate the number of players per team to see if this factor affects competitive game-play in junior football. Additionally, the mean distances maintained between players in the same team (team-mates) during game play needs to be considered (with regard to the ‘beehive effect’). Further studies should examine different age groups of equivalent skill level and assess their performance in relation to their technical kicking ability on different pitches.

Whilst smaller pitches have become the norm in junior football, they may still be too large for certain ages and levels of skill. To date there has been no research into the relationships between size of the pitch and the technical kicking ability (distance and accuracy) of young players (8 - 14 years of age). The purpose of this investigation was to examine variables that influence actual kicking distance and accuracy and also to measure what differences in play behaviour (passing and dribbling) emerge from self-selected changes in pitch size for different age groups (9 and 10 years of age). Data were collected on 120 (N=120) junior football players: Playing experience (M=2.85 years, SD=2.56), Height (M=1.44 m, SD=1.08), Weight (M=37.8 kg, SD=7.69), Lengths of lower limbs (knee/ankle: M=35.54 cm, SD=4.27; hip/knee: M=35.54 cm, SD=5.25), Step lengths (M=37.66 cm, SD=8.693), Estimated kicking distance (M=31.13 m, SD=16.63). Participants performed a series of three kicks along the ground, using the inside of the foot, and aiming for a target (25 m away). The distance (M=18.04 m; SD=6.56) and accuracy (M=8.32 m; SD=4.38) of each kick were measured. The children (9 and 10 years of age) were then assigned to teams and asked to construct a small-sided game on two different pitch sizes. The first pitch size used was the recommended regulation size. The second pitch size was self-selected by the players. Any changes to the playing dimensions (e.g., width of the pitch) and playing behaviours (e.g., total number of passes, dribbling) were measured and analysed. Kicking distance is best predicted by the player’s height (20.0%, P < 0.000), or a combination of the player’s height and estimated kicking distance (30.0%, P = 0.002). Kicking accuracy can be attributed to the influence of the player’s step lengths (8.1%, P = 0.016) and both their step lengths and estimated kicking distance (15.1%, P = 0.020). Furthermore, our findings demonstrate that the increase in pitch size (18.5% and 25%) resulted in a greater amount of dribbling (63% and 33%) and passing (12%). In general, our results support the idea that young children in New Zealand should be playing on a pitch and at a skill level which matches their football abilities. Grouping young players on a pitch according to their physical (e.g., height) and technical kicking ability (e.g., distance, accuracy) instead of their chronological age, seems to be the key factor to any other set of proposals. The findings of this thesis have important messages that could enhance the effectiveness of coaching, competitive game-play (pitch sizes) and consequently performance at all junior levels of football in New Zealand. Further research should manipulate the number of players per team to see if this factor affects competitive game-play in junior football. Additionally, the mean distances maintained between players in the same team (team-mates) during game play needs to be considered (with regard to the ‘beehive effect’). Further studies should examine different age groups of equivalent skill level and assess their performance in relation to their technical kicking ability on different pitches.

Small-sided soccer games (SSGs) are being widely used to improve the technical-tactical behavior and soccer-specific endurance simultaneously. However, there are numerous factors, which can influence the exercise intensity of SSGs. In this regard, a number of studies on SSGs reported the different physical demands and physiological responses according to the altering the number of players, pitch dimension etc. However, there are no studies, which investigated the energetic profiles from three energy pathways. Thus, the aim of this study is to quantify the energetic contributions in the relation of physical demands and physiological responses according to 1) altering the number of players and game duration (study 1), 2) pitch dimensions (study 2) and 3) further to explore which number of players and pitch dimensions can reproduce more closely to real soccer match (study 3). Thirty-four male junior soccer players from youth academy of German semi- and professional teams participated in this study. A portable spirometry system was used to validly record the proportionate energy supply mechanisms and the running load was recorded using a global positioning system (GPS). The heart rate (HR) and the post-exercise blood lactate concentration (BLa) were recorded before and after the respective exercise. For the calculation of the energetic contributions from three energy pathways the method developed by Beneke et al. (2002) was utilized. The subjects conducted three game formats i.e., 2 vs. 2, 4 vs. 4 and 6 vs. 6 for 2 min, 4 min and 4 min, respectively to examine the effect of altering the number of players. The results showed that three game formats had no difference in total distance covered, but 2 vs. 2 elicited greater distance covered in sprint than the other two ones. This was in accordance with the higher BLa during 2 vs. 2 than the other two ones. Besides, the values of heart rate (HR) and oxygen uptake (VO2) during 2 vs. 2 and 4 vs. 4 were higher than 6 vs. 6. In contrast to these results, the change of number of players and game duration had less impact on the energetic contributions. The energy supply for all game formats with different game duration relies mainly on the aerobic system with more than 70 - 90 % of total energy supply. The share of anaerobic energy accounted for less than 15 - 30 % of total energy supply. Particularly, the glycolytic share had very small influence on energy supply with less than 3 - 10 %. Moreover, the energetic contribution significantly depends on the individual fitness level. For the second purpose of this study the subjects performed 4 vs. 4 on the three different pitch dimensions (relative individual pitch dimensions; 66 m2: SSG66, 166 m2: SSG166, 266 m2: SSG266) during 4 min for each pitch dimensions. The results showed that total distance and sprint distance covered increased when the pitch dimension increased, and SSG166 and SSG266 led to higher HR, LA and %VO2 compared to SSG66. These physical demands and physiological responses were in line with the energetic contributions. The least total distance and sprint covered for SSG66 led to the least total energy turnover among three pitch dimensions. Moreover, the greater sprint distance covered for SSG166 and SSG266 than SSG66 resulted to the greater anaerobic and aerobic share compared to SSG66. However, the most of energy was supplied by the aerobic energy system (approximately 80 %) with very small glycolytic share, irrespective of pitch dimension. Furthermore, it was to investigate which number of players and pitch dimensions can reproduce more closely to real soccer match. The subject conducted four friendly matches during the study period. The response of HR and physical demands during 2 vs. 2 and 4 vs. 4 with three different pitch dimensions (individual playing area; 66 m2: 4 vs. 4PA66, 166 m2: 4 vs. 4PA166, 266 m2: 4 vs. 4PA266) were compared with the real soccer match. While all SSGs reproduced the HR (except for 4 vs. 4PA66) and demands of acceleration activity executed during the real soccer match, the demand of sprint could be reproduced by 4 vs. 4PA266 only. This study concludes that SSGs are a very effective and suitable tool to influence the dominant aerobic energy system of soccer-specific performance. Furthermore, there are possibilities to modify the number of players and the field dimensions depending on the training objective.:Abbreviations I List of figures II List of tables V Chapter 1. Introduction 1 1.1. State of problem 4 1.2. Structure of study 5 Chapter 2. Literature review 7 2.1. Trend analysis of study on SSGs 7 2.2. Effect of number of players 11 2.3. Effect of pitch dimension 19 Chapter 3. General methods 25 3.1. Subjects 25 3.2. Experiment equipments 26 3.3. Diagnostics of endurance performance 30 3.3.1. VO2max test 30 3.3.2. Incremental running test 32 3.3.3. Yo-Yo intermittent recovery test level1 34 3.4. Calculation method for energetic contributions from three energy pathways 36 Chapter 4. Study 1: Effect of number of players during SSGs on the physical and technical demands and physiological responses in relation with energetic profile 41 4.1. Introduction 41 4.2. Methods 43 4.2.1. Subjects 43 4.2.2. Study design 43 4.2.3. Dependent variables 46 4.2.3.1. Physical performance 46 4.2.3.2. The number of technical actions with ball 48 4.2.3.3. Energetic contributions and physiological responses 48 4.2.4. Experimental procedures 48 4.2.5. Statistics 50 4.3. Results 51 4.3.1. Physical performance during SSGs 52 4.3.1.1. Distance covered at various speed zones 52 4.3.1.2. Analysis of sprint effort 56 4.3.1.3. Distance covered in acceleration at various intensities 58 4.3.1.4. Number of acceleration at various intensities and relation of acceleration distance to total distance 63 4.3.1.5. Body load 65 4.3.2. Technical actions with ball 66 4.3.3. Physiological responses to SSGs 67 4.3.3.1. Response of heart rate during SSGs 67 4.3.3.2. Response of blood lactate concentration during SSGs 69 4.3.3.3. Response of oxygen uptake during SSGs 71 4.3.4. Summary of physical and physiological demands and technical actions with ball 73 4.3.5. Energetic contribution to SSGs 74 4.3.5.1. The absolute energetic contribution to SSGs during 1. bout 74 4.3.5.2. The relative energetic contribution to SSGs during 1. bout 77 4.3.5.3. The absolute energetic contributions to SSGs during 4. bout 79 4.3.5.4. The relative energetic contribution to SSGs for 4. bout 81 4.3.5.5. The absolute energetic contribution to 2 vs. 2 for 8. bout 84 4.3.5.6. The relative energetic contribution to 2 vs. 2 for 8. bout 85 4.3.5.7. Comparison of the energetic contribution between 1. bout and 4. bout within each game format 87 4.3.6. Summary of results for the energetic contribution 88 4.4. Discussion 90 Chapter 5. Study 2: Effect of pitch dimension during SSGs on the physical and technical demands and physiological responses in relation with energetic profile 110 5.1. Introduction 110 5.2. Methods 112 5.2.1. Subject 112 5.2.2. Study design 112 5.2.3. Dependent variables 114 5.2.4. Experimental procedures 114 5.2.5. Statistics 115 5.3. Results 116 5.3.1. Physical performance during 4 vs. 4 on three pitch dimensions 117 5.3.1.1. Distance covered at various speed zones 117 5.3.1.2. Analysis of sprint effort 121 5.3.1.3. Distance covered in acceleration at various intensities 124 5.3.1.4. Number of acceleration at various intensities and relation of acceleration distance to total distance 129 5.3.1.5. Body load 131 5.3.2. Technical actions with ball 132 5.3.3. Physiological responses to 4 vs. 4 on three pitch dimensions 133 5.3.3.1. Response of heart rate to 4 vs. 4 on three pitch dimensions 133 5.3.3.2. Responses of blood lactate to 4 vs. 4 on three pitch dimensions 134 5.3.3.3. Response of oxygen uptake to 4 vs. 4 on three pitch dimensions 135 5.3.4. Summary of physical and physiological demands and technical actions with ball 137 5.3.5. Energetic contribution during 4 vs. 4 on three pitch dimensions 138 5.3.5.1. The energetic contribution during 1. bout 138 5.3.5.2. The energetic contribution during 4. bout 140 5.3.5.3. Comparison of energetic contribution between 1. and 4. bout within each pitch dimension 142 5.4. Discussion 143 Chapter 6. Study 3: Comparison of heart rate and physical demands between SSGs and real soccer match according to number of players and pitch dimensions 157 6.1. Introduction 157 6.2. Methods 158 6.2.1. Subjects 158 6.2.2. Study design 158 6.2.3. Dependent variables 160 6.2.4. Experimental procedures 160 6.2.5. Statistics 161 6.3. Results 162 6.3.1. Comparison of heart rate between SSGs and matches 162 6.3.2. Comparison of physical demands between SSGs and matches 163 6.3.2.1. Distance covered at various speed zones 163 6.3.2.2. Analysis of sprint effort 164 6.3.2.3. Distance covered in acceleration at various intensities 165 6.3.2.4. Number of acceleration at various intensities 166 6.4. Discussion 166 Chapter 7. Limitation of methods 172 Chapter 8. General summary 175 Chapter 9. Practical application 183 References 186 Appendix 201 Eidesstattliche Erklärung / Kleinfeldfussballspiele (sog. Small-sided games: SSGs) werden seit geraumer Zeit eingesetzt, um sowohl das technisch-taktische Verhalten als auch das fussballspezifische Ausdauertraining zu schulen. Dabei gibt es jedoch zahlreiche Faktoren, die eine Einwirkung auf die Intensitätsgestaltung der SSGs haben, so z.B. Spieleranzahl, Feldgröße, Spielregeln etc. Frühere Studien untersuchten dabei die Veränderung der verschiedenen physiologischen, körperlichen und technischen Parameter in Abhängigkeit der oben genannten Einflussgrößen. Bis dato gibt es jedoch keine Studien, die die anteilige Energiebereitstellung bei SSGs abschätzt. Daher ist es das Ziel der vorliegenden Studien die anteiligen Energiebereitstellungen unter Berücksichtigung der läuferischen und physiologischen Belastungen und in Abhängigkeit von der Spieleranzahl, Spielzeit (Studie 1) und Feldgrößen (Studie 2) zu quantifizieren. Darüber hinaus wurde auch untersucht, Welche Spielformen und Feldgröße die reale Wettkampfintensität näherungsweise abbilden können (Studie 3). Zur validen Erfassung der anteiligen Energiebereitstellungsmechanismen wurde ein portables Spirometriesystem verwendet und die Laufbelastung mittels eines Global Positioning Systems (GPS) erfasst. Vor und nach den jeweiligen Belastungen wurden die Herzfrequenz (HF) als auch die Nachbelastungsblutlaktatkonzentration (BLa) erhoben. Die Kalkulation bzw. Bestimmung der anteiligen Energiebereitstellungsprozesse erfolgte in Anlehnung an das Modell von Beneke et al. (2002). Alle Probanden absolvierten Spielformen 2 gegen 2 mit zweiminütiger Belastungszeit sowie 4 gegen 4 und 6 gegen 6 mit vierminütiger Belastungszeit; alle drei Spielformen wiesen keinen Unterschied bei der zurückgelegten Gesamtdistanz auf, die Spielform 2 gegen 2 zeigte im Vergleich zu den anderen Spielformen eine höhere Sprint- und Beschleunigungsdistanz. Diese Ergebnisse gingen einher mit höheren BLa-Werten bei 2 gegen 2 im Vergleich zu den anderen Spielformen. Die Herzfrequenz und die Sauerstoffaufnahme lagen bei 2 gegen 2 und 4 gegen 4 höher als bei 6 gegen 6. Im Gegensatz zu den Differenzen in der Laufbelastung zeigten HF und VO2 zwischen drei Spielformen nur einen geringen Einfluss auf die anteilige Energiebereitstellung. Bei allen Spielformen lag der größte Anteil der Energiebereitstellung im Bereich des aeroben Stoffwechsels mit mehr als 70 - 90 %. Der anaerobe Anteil betrug weniger als 15 - 30 % der gesamten Energiebereitstellung, wobei insbesondere der glykolytische Anteil mit 3 - 10% insgesamt sehr gering war. Es ergab sich weiter, dass die anteilige Energiebereitstellung vom individuellen konditionellen Niveau abhängig ist. Um den Einfluss der Feldgröße zu untersuchen absolvierten die Probanden die Spielform 4 gegen 4 auf drei unterschiedlichen Feldgrößen (kleine Feldgröße = KF, mittlere Feldgröße = MF und große Feldgröße = GF) mit jeweils vierminütiger Belastung. Es konnte beobachtet werden, dass die zurückgelegten Gesamtdistanzen und Sprintdistanzen auf MF und GF länger als auf KF waren. Die jeweils ermittelte VO2, HF und BLa auf MF und GF waren größer als auf KF. Erwartungsgemäß wiesen die geringsten Gesamt- und Sprintdistanzen auf dem KF auch den niedrigsten Gesamtenergieumsatz auf. Größere Anteile an Sprintdistanz auf MF und GF hatten höhere anaerobe und aerobe Anteile im Vergleich zu KF zur Folge. Trotzdem wird, unabhängig von der Feldgröße, der größte Anteil der Energiebereitstellung über den aeroben Stoffwechsel (ca. 80 %) mit einem sehr geringen glykolytischen Anteil abgedeckt. In weiteren Verlauf der Untersuchungen absolvierten die Probanden vier Wettkampfspiele, wobei die Laufbelastung und die HF der Wettkampfspiele mit der Belastungssituation 2 gegen 2 und 4 gegen 4 auf drei Feldgrößen verglichen wurden. Die Befunde zeigten, dass die Spielformen 2 gegen 2 und 4 gegen 4 auf MF und GF die HF und Beschleunigungsbelastungen der realen Wettkampfspiele weitgehend abbilden konnten. Als zusammenfassende Konsequenz kann statuiert werden, dass SSGs je nach der angedachten Verwendung ein sehr probates und geeignetes Mittel darstellen, den primär aeroben Anteil der fussballspezifischen Leistung in Training und Wettkampf zu beeinflussen bzw. zu trainieren. Weiter ergibt sich insgesamt ein sehr umfangreiches und breites Spektrum, die Spieleranzahl und Feldgröße je nach Trainingsziel entsprechend zu modifizieren und gemäß den jeweiligen trainingsmethodischen Zielsetzungen für die Belange in der Praxis auszurichten.:Abbreviations I List of figures II List of tables V Chapter 1. Introduction 1 1.1. State of problem 4 1.2. Structure of study 5 Chapter 2. Literature review 7 2.1. Trend analysis of study on SSGs 7 2.2. Effect of number of players 11 2.3. Effect of pitch dimension 19 Chapter 3. General methods 25 3.1. Subjects 25 3.2. Experiment equipments 26 3.3. Diagnostics of endurance performance 30 3.3.1. VO2max test 30 3.3.2. Incremental running test 32 3.3.3. Yo-Yo intermittent recovery test level1 34 3.4. Calculation method for energetic contributions from three energy pathways 36 Chapter 4. Study 1: Effect of number of players during SSGs on the physical and technical demands and physiological responses in relation with energetic profile 41 4.1. Introduction 41 4.2. Methods 43 4.2.1. Subjects 43 4.2.2. Study design 43 4.2.3. Dependent variables 46 4.2.3.1. Physical performance 46 4.2.3.2. The number of technical actions with ball 48 4.2.3.3. Energetic contributions and physiological responses 48 4.2.4. Experimental procedures 48 4.2.5. Statistics 50 4.3. Results 51 4.3.1. Physical performance during SSGs 52 4.3.1.1. Distance covered at various speed zones 52 4.3.1.2. Analysis of sprint effort 56 4.3.1.3. Distance covered in acceleration at various intensities 58 4.3.1.4. Number of acceleration at various intensities and relation of acceleration distance to total distance 63 4.3.1.5. Body load 65 4.3.2. Technical actions with ball 66 4.3.3. Physiological responses to SSGs 67 4.3.3.1. Response of heart rate during SSGs 67 4.3.3.2. Response of blood lactate concentration during SSGs 69 4.3.3.3. Response of oxygen uptake during SSGs 71 4.3.4. Summary of physical and physiological demands and technical actions with ball 73 4.3.5. Energetic contribution to SSGs 74 4.3.5.1. The absolute energetic contribution to SSGs during 1. bout 74 4.3.5.2. The relative energetic contribution to SSGs during 1. bout 77 4.3.5.3. The absolute energetic contributions to SSGs during 4. bout 79 4.3.5.4. The relative energetic contribution to SSGs for 4. bout 81 4.3.5.5. The absolute energetic contribution to 2 vs. 2 for 8. bout 84 4.3.5.6. The relative energetic contribution to 2 vs. 2 for 8. bout 85 4.3.5.7. Comparison of the energetic contribution between 1. bout and 4. bout within each game format 87 4.3.6. Summary of results for the energetic contribution 88 4.4. Discussion 90 Chapter 5. Study 2: Effect of pitch dimension during SSGs on the physical and technical demands and physiological responses in relation with energetic profile 110 5.1. Introduction 110 5.2. Methods 112 5.2.1. Subject 112 5.2.2. Study design 112 5.2.3. Dependent variables 114 5.2.4. Experimental procedures 114 5.2.5. Statistics 115 5.3. Results 116 5.3.1. Physical performance during 4 vs. 4 on three pitch dimensions 117 5.3.1.1. Distance covered at various speed zones 117 5.3.1.2. Analysis of sprint effort 121 5.3.1.3. Distance covered in acceleration at various intensities 124 5.3.1.4. Number of acceleration at various intensities and relation of acceleration distance to total distance 129 5.3.1.5. Body load 131 5.3.2. Technical actions with ball 132 5.3.3. Physiological responses to 4 vs. 4 on three pitch dimensions 133 5.3.3.1. Response of heart rate to 4 vs. 4 on three pitch dimensions 133 5.3.3.2. Responses of blood lactate to 4 vs. 4 on three pitch dimensions 134 5.3.3.3. Response of oxygen uptake to 4 vs. 4 on three pitch dimensions 135 5.3.4. Summary of physical and physiological demands and technical actions with ball 137 5.3.5. Energetic contribution during 4 vs. 4 on three pitch dimensions 138 5.3.5.1. The energetic contribution during 1. bout 138 5.3.5.2. The energetic contribution during 4. bout 140 5.3.5.3. Comparison of energetic contribution between 1. and 4. bout within each pitch dimension 142 5.4. Discussion 143 Chapter 6. Study 3: Comparison of heart rate and physical demands between SSGs and real soccer match according to number of players and pitch dimensions 157 6.1. Introduction 157 6.2. Methods 158 6.2.1. Subjects 158 6.2.2. Study design 158 6.2.3. Dependent variables 160 6.2.4. Experimental procedures 160 6.2.5. Statistics 161 6.3. Results 162 6.3.1. Comparison of heart rate between SSGs and matches 162 6.3.2. Comparison of physical demands between SSGs and matches 163 6.3.2.1. Distance covered at various speed zones 163 6.3.2.2. Analysis of sprint effort 164 6.3.2.3. Distance covered in acceleration at various intensities 165 6.3.2.4. Number of acceleration at various intensities 166 6.4. Discussion 166 Chapter 7. Limitation of methods 172 Chapter 8. General summary 175 Chapter 9. Practical application 183 References 186 Appendix 201 Eidesstattliche Erklärung