Elite youth soccer player’s performance depends on a multitude of factors (Stølen et al. 2005). Muscular force production capability is of likely importance due to the frequency of powerful actions that occur within match play (Faude et al. 2012). Little is known though of the training undertaken at elite youth soccer academies to increase muscular force production capabilities particularly across maturation groups. There is also little evidence around the nature, or genetic influence on this variable in these populations. Greater knowledge on these areas would be beneficial to aid an understanding of performance and to plan practical interventions. Eight weeks of training for players in the under 9 (U9) through to under 21 (U21) age groups (Chapter 3) were recorded to investigate the duration of each training type completed. The total training duration increased from U9 to U14 before reducing at U15 and then remaining unchanged through to, and including, the U21 age group. Soccer training accounted for 97 ± 4 % of session time in the U9 to U14 groups and 74 ± 3 % in the U15 to U21 groups. The remainder of training was made up of work that was not soccer based. The data in this case study suggest that training time is focussed on the technical/tactical development throughout the academy, particularly in the younger age groups. Study 2, part A (Chapter 4) provided baseline isometric maximal voluntary force (MVF) data for players and an maturation-matched non-elite control group. MVF was slightly higher in the elite compared to control cohorts during an isometric mid-thigh pull (IMTP, 118.29 ± 13.47 N compared to 109.69 ± 17.00 N). Such data may indicate that ability to produce force, specifically isometric MVF, may not be a crucial determinant of performance in elite youth soccer based on this sample. The purpose of study 2, part B (Chapter 4) was to establish the effect of 8 weeks typical training on elite youth soccer players’ IMTP MVF. This was also compared to a non-elite control cohort matched for maturation status and not undertaking training. Isometric MVF did not change in either group over the 8 week period (P = 0.386). These data suggest that this elite youth soccer training simply maintained current strength levels and was not sufficient to elicit increases in isometric MVF. Study 3 (Chapter 5) examined variations in four separate genes, all identified as potentially having an influence on muscular force production capabilities: PPARA rs4253778, NOS3 rs2070744, COLIA1 rs2249492 and VDR rs2228570. Allele and genotype frequency was determined along with the influence of those single nucleotide polymorphisms (SNPs) on isometric MVF. Only NOS3 was different in genotype distribution between cohorts with TT genotype showing 45.0 % and 30.4 % frequency in elite and control cohorts respectively (P < 0.001). Furthermore, no difference was seen between cohorts for isometric MVF data when comparing influence of any genotypes of any gene. These data provide novel information around genotype frequency in this population and would suggest that the gene variations examined here might not play a role in force production in these populations. Overall, these findings suggest that muscular force production may be important for elite youth soccer performance, but that current training practices to improve this characteristic should be revised. This seems especially relevant given the lack of genetic association with force production in the gene variations examined here, i.e. elite youth soccer players do not appear to be selected based on a genetic predisposition for greater isometric force production capabilities.

Delayed onset muscle soreness (DOMS) is a muscle strain injury that presents as tender or aching muscles, often felt during palpation or movement. DOMS is associated with unaccustomed, high-force muscular work and is most pronounced if the work involves a significant eccentric component. Despite substantial research into DOMS its aetiology is still unresolved. There have been recent suggestions that reactive oxygen species (ROS) may be involved in the aetiology of DOMS, however the evidence for this association is equivocal. Therefore, the aims of this thesis were to investigate the effects of unaccustomed exercise (downhill running) on DOMS, specifically investigating the role of ROS in its aetiology. Once this had been established, the effects of dietary intervention and antioxidant supplementation on DOMS and ROS were also investigated. Study 1 demonstrated that downhill running, which resulted in DOMS, also induced the production of ROS, detected by ESR spectroscopy as well as an increases in serum malondialdehyde (MDA) concentration. It was noted that this increase in ROS occurred -72 h post exercise and was therefore likely to be a result of increased phagocyte activity. Furthermore, the increase in ROS occurred after peak DOMS and when muscle function (as determined by losses of muscle torque assessed by isokinetic dynamometry) was returning to pre-exercise levels, suggesting a temporal dissociation between ROS production and DOMS following downhill running. Circulating levels of ROS were still increasing 72 h post exercise so this study was unable to map the full time-course of ROS production following downhill running. Study 2 investigated the effects of dietary CHO intake on DOMS, ROS and muscle function. It was found that pre-exercise CHO status had no effect on ROS production, DOMS or losses of muscle function following downhill running. The study demonstrated a bi-phasic increase in creatine kinase (CK), with the second increase corresponding with the post-exercise ROS production. The study extended the postexercise sampling period to 96 h, however, ROS were still increasing at this time and therefore this study was also unable to conclude a definitive tune course of ROS production following downhill running. Study 3 demonstrated that prolonged ascorbic acid supplementation attenuated the post-exercise increase in ROS production compared to placebo. This attenuation in ROS prevented the secondary peak in CK activity, however it had no effect on DOMS. Interestingly, supplementation with ascorbic acid resulted in more prolonged losses of muscle function. ROS peaked at 96 h post exercise and therefore the time course ofROS production following downhill running was established. From these studies it was concluded that downhill running did result in post-exercise ROS production. This post-exercise ROS production was associated with secondary muscle damage as measured by plasma CK activity although it had no effect on DOMS. Since supplementation with ascorbic acid attenuated ROS production and prolonged the losses of muscle function, it was suggested that ROS produced by phagocytes m the days following muscle-damaging exercise have a positive role in assisting in the recovery from the trauma.

No description available.

No description available.

The thesis outlines a collaborative research project that was undertaken between the Malta Football Association (MFA), the Malta National Sports School (NSS) and Liverpool John Moores University (LJMU). Drawing on transition frameworks, models and contemporary literature (Schlossberg, 1981; Stambulova 2003; Wylleman & Lavalle, 2004; Morris, Tod & Oliver, 2015; Morris, Tod & Eubank, 2016; Richardson, Littlewood & Gilbourne, 2005; Richardson, Littlewood, Nesti & Benstead, 2012), the research adopted an action research methodology to examine the psycho-social and cultural challenges that young Maltese football players and parents experienced within migratory based transitions. The author adopted the role of practitioner-researcher to understand, plan and support a range of key stakeholders during the transition process. Specifically, Study One (Reconnaissance Phase) examined the challenges experienced by Maltese footballers that had migrated to European professional football. Individual semi-structured interviews were conducted with 12 male Maltese players who had experienced migration to a foreign club. Results evidenced that players experienced homesickness and lacked psycho-social knowledge and skills for an effective transition. Players also experienced culturally based challenges. The findings are framed around a unique and deeply embedded Maltese cultural identity. Study Two (Reconnaissance Phase) utilised a focus group methodology with parents of players from the Maltese Football Association (MFA) Academy, parents of young players that had previously experienced migration, head coaches from top Maltese nurseries, and coaches from the National Sports School (NSS) and MFA. Findings of Study One were disseminated to facilitate reflection, discussion and to identify issues that required consideration in order to better prepare young players for future migratory based transition. Study Three (Action Planning) used focus groups to disseminate the findings of Study One and Two with the Headmaster of the NSS, and parent representatives of the school. A number of change strategies were developed to improve the school’s programme of preparation for students who may migrate to foreign clubs. A separate action meeting was conducted with the Technical Director of the MFA to discuss and highlight change strategies to improve the MFA’s programme of preparation for young footballers seeking a career abroad in professional football. The Implementation and Monitoring phases focused on applying the action strategies agreed. These were; (i) to experience migration and independent living, (ii) psycho-social and cultural support and development of young players, and (iii) parental education. Regular evaluation of change strategy activities evidenced positive change and also continued to enhance the efficacy of the strategies being implemented. Young players who have migrated overseas over the past year and who had engaged in a programme of preparation prior to migration have coped well with the challenges they have so far faced.

There is no information available in the scientific literature that documents a specific assessment protocol for analysing a soccer player’s maximal power capabilities. As soccer-associated muscular power has not previously been investigated, it is not known how important power is in elite soccer and, if it is, the physiological and genetic determinants of soccer-associated power remain unknown. Such information could be used to optimise soccer-specific talent identification and development strategies. With this in mind, the overriding aim of our thesis was to investigate the physiological and genetic factors underpinning powerful actions in elite youth soccer. When devising an assessment of soccer-associated muscular power, there needs be a detailed analysis of the specific actions performed during elite competitive match-play that can be described as powerful. The aims of our first experimental study (Chapter Three) were to compare the frequency and durations of powerful actions during competitive English Premier League [under 18 (U18) and under 21 (U21)] elite youth soccer matches using a novel soccer specific powerful action (SSPA) notational analysis coding system. We found that while elite soccer match-play requires players to perform powerful actions in multiple directions [68 horizontal accelerations (in the horizontal-forward or mediolateral directions), eight sprints, and six vertical jumps (three bilateral and three unilateral)], horizontal accelerations of short duration (< 1.5 s) from different starting speeds were the most dominant type of explosive action. This activity profile provides a strong rationale for devising a muscular power assessment protocol that evaluates the ability to produce maximal power in multiple directions, from a unilateral stance. Our data also suggests that such a protocol could provide a specific lower body power profile in elite soccer players (ESP). The aim of our second study (Chapter Four) was therefore, to determine whether countermovement jumps (CMJs) in different directions [CMJs: bilateral vertical (BV), unilateral vertical (UV), unilateral horizontal-forward (UH) and unilateral medial (UM)] assessed independent lower-limb power qualities, and if CMJ performance differed between ESP (representing an English Premier League Academy regularly at U18 and under U21 levels) and non-elite soccer players (NSP). We found that unilateral CMJs in different directions assessed independent peak vertical power (V-power) and resultant take-off velocity capabilities, and the UH CMJ required significantly greater bicep femoris electromyographic (EMG) activation in comparison all other CMJs. Moreover, in comparison to NSP, ESP achieved greater V-power during all CMJs (p≤0.032) except for BV (p=0.197), and also achieved greater UH CMJ projectile range (51.6 ± 15.4 vs. 40.4 ± 10.4 cm, p=0.009). Our results suggest that unilateral CMJs in different directions, but not the commonly used BV CMJ, are determinants of U18 and U21 elite soccer playing status and can be used by applied practitioners as independent assessments of soccer-associated muscular power. As the physiological determinants of performance are of use to the applied practitioner for informing talent identification criteria, and prescribing detailed training intervention strategies, the primary aims of the third and fourth studies were to investigate the neuromuscular (Chapter Five) and tendon (Chapter Six) determinants of unilateral CMJs oriented in different directions. Our data suggests that unilateral CMJ performance is associated with direction-specific neuromuscular and tendon properties in U18 and U21 ESP. While UV CMJ performance was related to the size (quadriceps femoris muscle volume and physiological cross sectional area), architecture (vastus lateralis pennation angle) and ability to activate (vastus lateralis EMG activation level) the knee extensor muscles, UH CMJ performance was related to the elongation and compliance properties of the patellar tendon, and was inversely correlated with vastus lateralis fascicle pennation angle. Our findings highlight the importance of targeting specific neuromuscular and tendon properties when assessing and developing muscular power performance in U18 and U21 ESP. Many physiological changes occur during puberty (Viru et al., 1999) and our findings in Chapters Four, Five and Six may only be applicable in U18 and U21 ESP. Therefore, in our fifth study (Chapter Seven) we aimed to investigate the importance of acceleration, sprint, horizontal-forward CMJ and vertical CMJ capabilities at different stages of maturation in elite youth soccer. Elite soccer players and CON were grouped using years from/to predicted peak height velocity (PHV, a measure of growth velocity and an indirect measure of pubertal phase) to determine maturation status (ESP: pre-PHV, n=100; mid-PHV, n=25; post-PHV, n=88; CON: pre-PHV, n=44; mid-PHV, n=15; post-PHV, n=54). By comparing performance of ESP and control participants (CON) matched for maturation status, we found that acceleration and sprint performance were associated with elite youth soccer at all stages of maturation, but maximal power (horizontal-forward and vertical jumping) capabilities may only be important for elite youth soccer at mid- and post-peak height velocity. Our data could imply that assessments of acceleration and sprint capabilities should be included in soccer talent identification protocols at all stages of maturation, but maximal power should only be included at mid- and post-PHV. The purpose of our sixth experimental study (Chapter 8) was to investigate if specific gene single nucleotide polymorphisms [SNPs: ACTN3 R577X (rs1815739), BDNF G > A (rs6265), COL5A1 C > T (rs12722), and COL2A1 C > T (rs2070739)] played a role in determining elite youth soccer player status, and speed and power capabilities, in ESP and CON at different stages of maturation. We found that ACTN3 R- and BDNF G-allele frequencies were more frequent in post-PHV compared to pre-PHV ESP. Moreover, while the COL2A1 CC genotype was associated with greater horizontal power and faster 20 m sprint performance, BDNF GG genotype appears to positively influence 20 m sprint performance during the pre-PHV period only. Overall, our findings illustrate that elite soccer may require different genetic profiles before and after maturation, and genetic screening could be included in talent identification criteria to help predict maximal power and sprint potential in ESP. In summary, we devised a muscular power assessment battery that measured independent power qualities and could discriminate between U18 and U21 ESP and NSP. Our subsequent analysis showed that the physiological factors underpinning unilateral CMJ performance were direction-specific, and UV and UH CMJ capabilities were underpinned by separate neuromuscular and tendon properties, and should be assessed and developed, independently in U18 and U21 ESP. We then recruited a larger cohort of ESP and CON, at different stages of maturation, and demonstrated that muscular power was important for elite soccer performance at mid and post-PHV, but not pre-PHV. Finally, we showed that genetic profiles of ESP differed between pre- and post-PHV, and that certain gene variants [COL2A1 C > T (rs2070739), BDNF G > A (rs6265)] were associated with specific power and speed capabilities in ESP. Overall, our studies provide novel information that could have significant implications on soccer-associated power related talent identification and training intervention strategies in elite youth soccer academies.

Despite the wealth of research examining physical activity (PA) in children and adolescent without disability, there is a lack of research that has focussed on PA related to children and adolescents with intellectual disabilities (ID). The evidence that does exist in this area suggests that children and adolescents with ID are less active than their non-ID peers. The school environment offers numerous opportunities to engage in PA regularly, yet to date, school-based research focussing on PA in children and adolescents with ID is limited. Thus, the primary aim of this thesis was to investigate PA, sedentary time (ST) and playtime behaviours in children and adolescents with ID.Four study chapters are included in the thesis. Study 1 used uniaxial accelerometers to investigate habitual PA levels, sedentary behaviour and PA patterns in children and adolescents with severe and moderate ID. Results demonstrated that participants engaged in low amounts of PA, spent a large proportion of waking hours in ST and mainly engaged in short, sporadic bursts of PA.Study 2 investigated the PA levels of children and adolescents with severe and moderate ID during playtime and PE contexts using direct observation techniques. Participants engaged in similar levels of moderate to vigorous PA (MVPA), and spent minimal amounts of time engaging in sport based activities during playtime and PE. At playtime participants spent the majority of time playing alone or in small groups and no participants engaged in any large group play. Study 3 explored teachers’ perceptions of PA engagement for children and adolescents with ID. Teachers reported that pupils prefer to engage in fun, unstructured activities. Parents and teachers were identified as key role models who can influence PA engagement for this population and teacher participants explained that pupils with ID have limited understanding around PA and the benefits to health. Study 4 evaluated the effectiveness of a school-based PA intervention, delivered in two primary special educational needs (SEN) schools. The intervention demonstrated promising results, with an increase in accelerometer assessed MVPA levels between baseline and follow up of ~18mins. However, these findings were not statistically significant, possibly due to the small sample size involved. Minimum clinically important difference analysis suggested that changes in MVPA were likely to be beneficial to heath. Furthermore, qualitative data generated through teacher interviews highlighted positive intervention effects across the school. Overall the studies presented in this thesis provide an overview of PA engagement and associated behaviours in children and adolescents with ID. The major findings presented suggest that children and adolescents with moderate and severe ID are not sufficiently active, and the SEN school environment may be an important area to target PA interventions. The current thesis has made a significant contribution to our understanding related to the PA in children and adolescents with ID and has highlighted a number of recommendations for future research.

No description available.

During the 9th lunar month of each year around 1 billion Muslims adhere to the religious 4- week festival of Ramadan, which is considered as a time for empathy for those less fortunate, a time for restraint, and goodwill. The main focus of the religious intervention of Ramadan is the intermittent fast whereby, each day between dawn and sunset nutritional abstinence is practiced. Empirical evidence from experienced soccer coaches in Qatar has indicated that the 4-week intermittent fast during Ramadan impedes the quality and quantity of training, as well as match play. However, there has been lack of attention directed to the consequences associated with Ramadan and football (soccer) players. Greater understanding of the consequences of Islamic soccer players adhering to lifestyle changes and intermittent fasting would facilitate soccer coaches in a systematic approach to addressing potential negative performance effects associated with Ramadan in future soccer-seasons. In order to address the research problem, a soccer-specific battery of tests was required; as there is no established gold standard battery of soccer-specific field tests preliminary technical and methodological studies were required. In Study-1 a soccer-specific anaerobic capacity field test (Liverpool Anaerobic Speed Test or LAST) was piloted for validity, reliability, and practicality since, the choice for suitable soccer-specific anaerobic capacity tests were inadequate. It was found that two familiarisation sessions are necessary to reduce systematic bias markedly and habituate players with procedures of the LAST. The total measurement error (ratio of Limits of Agreement) of the LAST was 2.5% (± 18 m), and peak blood lactate values produced were 17.6 mmol.l⁻¹, which were greater than the 14.7 mmol.l⁻¹ criteria set for maximal anaerobic effort before the pilot study. The test set-up and administration proved to be practical, facilitating large numbers of subjects to be evaluated relatively quickly ( < 20 min). Therefore, the LAST was included in the soccer-specific battery of field tests, which then provided a comprehensive analysis of the separate components soccer performance. The available facility to conduct this investigation was the soccer-field at Al-Ahli Sports Club Doha, Qatar and therefore, further methodological investigations were necessary; temperatures within Qatar can vary during different times of the season, and at times are quite severe with respect to heat and humidity. The purpose of Study-2 was to examine how robust the discrete soccer-specific field tests were which, would be used during the intervention of Ramadan, using a repeated measures counter-balanced design of indoor and outdoor conditions. It was found that during the Yo-Yo Intermittent Recovery Test (YYIRT) (Krustrup et al., 2003) outdoor assessment maximal performance was reduced by 19% in contrast to the YYIRT conducted indoors, despite the subjects attaining similar maximal heart rates. Consequently, the YYIRT to volitional exhaustion was excluded from the battery of tests to be used during the intervention of Ramadan; all other soccer-specific field tests were found to be robust for use in the heat. The aim of Study-3 was a qualitative investigation to observe current soccer-practice and related factors surrounding training; this brief included bedtime, wake-up time, sleep duration, environmental conditions, pre-training dehydration, body fluids lost during training, body-core temperature, and relative training intensity. During Ramadan it was found that bedtime and wake-up time were significantly delayed and sleep duration lengthened compared to normal. Post-Ramadan was found to be akin to eastward time travel with advancement in bedtime, wake-up and return to normal sleep duration. Dehydration was significantly greater pre-training during Ramadan in comparison to non- Ramadan training weeks, and body fluid loss during training in both Ramadan and non- Ramadan periods was considerable. Relative training workload was also quantified during this time and highlighted important practical problems.

As natural environments have been identified as places for mental restoration and social development there is the potential to address a number of bio-psychosocial health inequalities by encouraging urban park use. The current research explores the link between people and nature within the urban context of Liverpool across 3 phases of research. The reconnaissance phase explored health inequalities, physical activity levels and park access in Liverpool. Analysis showed that Liverpool is one of the most socially and economically deprived areas within England, with less than 70% of the survey population not meeting recommended physical activity levels. Although Liverpool has an abundance of parks and urban green spaces, the high health inequalities and lack of physical activity correlation with environment features suggests residents might not access parks and urban green spaces for health benefits. The exploratory study adopted a multi-method approach to investigate bio-psychosocial responses to urban city and park environments. Using repeated measures, 18 participants walked on a treadmill for 20 minutes whilst viewing and listening to either a Liverpool urban park or city centre scene. A two-way ANOVA was conducted to compare means between data collection time points within each condition for heart rate and blood pressure. Analysis for mean arterial pressure found a significant reduction for the park condition post physical activity [F(2,18) 6.83, p=.02] with the same effect on systolic blood . pressure [F(2, 18)=8.61, p=.OO] in comparison to the city scene. Semi-structured interviews conducted after testing found that cultural and social experiences influenced how participants interact with the urban environment. In particular, opportunities to access parks and natural environments during childhood was attributed to a lifespan connection. Participants reported psychological benefits of stress reduction and attention restoration and social benefits including providing a place for family and friend interaction in a park setting. Social barriers included fear from crime and harassment from teenagers. While the city was associated with traffic, congestion and noise that could evoke negative emotions, the history and diversity of Liverpool aroused pride and enjoyment that could also promote psychosocial benefits. The intervention study adopted ethnographic principles to explore cultural and individual beliefs of a group of eleven teenagers engaged in a park based physical activity programme. Observations during the programme indicated that the practitioner's role and skill base was paramount to park and activity engagement. Changes to participants across the programme impacted negatively on group dynamics, with external pressures from family and friends contributing to low attendance rates, poor time keeping and low concentration during activities. The social intervention highlighted the need to fully engage participants in the planning process and provide an agreed structure and policy for behaviour. The research highlighted a number of organisational, cultural and social issues that need to be tackled before benefits from green spaces can be fully realised. Overall research findings suggest that potential bio-psychosocial benefits of physical activity in parks and urban green spaces may be influenced by complex social issues surrounding values, culture and tradition. Further investigation into the interrelationships between neighbourhood residents, parks and urban green spaces, activities of users, and potential restorative effects could provide beneficial insights for policy makers and practitioners who would look to use these spaces for bio-psychosocial wellbeing.