Dynamic loading profiles beneath the human foot during sideslope walking were determined and differences to level walking established. The contact area of the foot was measured, and the arch index derived from the footprint. Thirty healthy adults walked on a tillable walkway which had a polymer sensor pressure platform mounted at the mid-point. The sideways tilt could be adjusted in 2° increments from level to 8°. By walking in both directions on the sideslope, volunteers placed their right foot in either the upslope or downslope position. Loading profiles and contact areas were recorded for upslope and downslope foot placements at each angle of tilt. The characteristics of the electrically resistive polymer sensors were determined prior to the walking trials. The sensor output was non-linear, mean within-sensor variation =3% (maximum 8%), mean hysteresis -9% (maximum 13%), pressure threshold sensitivity =35 kPa, and mean between-sensor variation =8% (maximum 18%) over the surface of the platform. The dynamic behaviour was reliable to 26Hz. The sensor was found to be sensitive to shear. The impact of this characteristic was assessed by comparison with a similar platform incorporating capacitive transducers that were not shear sensitive. The polymer sensor system indicated increased pressures beneath the heel with upslope foot placement, and similar increases beneath the central metatarsals with downslope placement. These features were not apparent in the profiles returned by the second platform. For both platforms, however, the first metatarsal showed increased pressures with downslope placement but decreased pressures with upslope placement. In addition, the initial contact time and duration of loading for the first metatarsal altered significantly. The contact area of the foot changed systematically with sideslope walking, such that the arch index increased with upslope placement and decreased with downslope placement. This study demonstrated that the conventional approach of assessing level walking would fail to identify the increased foot pressures that occur on sideslopes. This may have crucial implications for ulceration risk assessment. The systematic changes in arch index and first metatarsal loading indicate that sideslope walking might be beneficial in revealing aspects of the mechanical behaviour of the human foot if combined with a simultaneous kinematic analysis. Potentially, the method offers a new approach to assessing the functional capacity of the foot for both clinical and research purposes.

Fundamental movement skills (FMS) are a vital part of a child’s development, which allow them to advance on to more complex movements, resulting in them functioning successfully in their daily lives and when participating in sports and physical activity. Despite the importance of FMS, previous studies have routinely found children to have low competency levels. Further research on competency levels in this area is required, specifically among UK children, as data on FMS proficiency and FMS interventions is dominated by research from Australia and North America. As such, the aims of this thesis were to a) document the level of FMS competency of preschool children from a highly deprived area of Northwest England, b) determine the effectiveness of a six-week Active Play intervention on FMS competency among preschool children from a highly deprived area of Northwest England, c) examine the relationship between FMS competency, physical activity and weight status over a five-year period between preschool and late primary among children from a highly deprived area of Northwest England and finally, d) gain the thoughts and opinions of experts and practitioners in order to help inform the development of an appropriate intervention to increase the physical literacy of preschool children.

Within youth soccer high training and match loads warrant appropriate nutritional attention, although research assessing the nutritional intake and habits of youth soccer players is scarce. This thesis aimed to investigate habits and explore experiences of dietary intake methods in an English Premier League youth academy. Study one (Chapter 4) quantified the energy, macro and micronutrient intake of players from age groups under (U) 13 to U18 (7-day food diary, n = 59). Results showed players across all ages were in energy deficit, with low carbohydrate intake, and a large individual variability for micronutrient intake in comparison to current recommendations. However, under-reporting may have influenced these results. Study two (Chapter 5), a qualitative approach, explored nutritional habits (n = 15) with study one participants using one-on-one interviews. The U15 – U18s players consciously periodise their carbohydrate intake throughout the week; U18s stated this was to aid body composition. When discussing their participation in the previous food diary study, U18s expressed that a quicker, more user-friendly method would be desirable. The third study (Chapter 6), therefore, assessed the use of smartphone technology to record dietary intake. Fulltime youth soccer players (n = 22) recorded their dietary intake on a single training day, using a smartphone application and a photography method respectively compared to 24-hr recall. The 24-hr recall provided significantly higher energy and macronutrient intake in comparison to the smartphone methods. This data suggests smartphone technology was more effective in tandem with 24-hr recall. To conclude, youth soccer players are in dietary energy and carbohydrate deficit, with variable micronutrient intake when compared to current recommendations and traditional 24-hr recall is recommend if using smartphone technology. Further research for the accurate quantification of dietary intake and energy demands is required. Dietary advice provision for youth soccer to reach current nutritional recommendations is warranted.

Ramadan requires individuals to abstain from food and fluid intake between sunrise and sunset; physiological considerations predict that poorer mood, physical performance and mental performance will result. In addition, any difficulties will be worsened because preparations for fasting and recovery from it often mean that nocturnal sleep is decreased in length, and this independently affects mood and performance. Previous field studies have indicated that some of these predictions are borne out in practice; in the first study of the present thesis, a field study performed in Libya, these predictions were tested further by adding more physiological measurements and tests of performance. Findings indicated that Ramadan was associated with negative effects upon a wide range of variables, including rising urine daytime osmolality (indicative of progressive dehydration), subjective estimates of amounts of activities actually performed and those wished to be done (indicating less activity in the daytime), and metabolic and subjective responses to a short bout of exercise (increased effort required and metabolism tending towards fat rather than glucose catabolism). Because of the difficulties of performing a battery of tasks in a field study, two laboratory-based experiments were then performed, the second differing from the first in studying a greater range of variables and more time-points during the daytime. These two studies also differed from the situation in Ramadan in that non-Muslim students were volunteers and fasting was performed for only one day. Many of the changes previously found in Ramadan were duplicated in this work, so justifying the use of laboratory experiments lasting one day and using non-Muslim subjects as a model for some of the problems present in Ramadan. However, it was also found that preparations before the fast were often less marked than was the case with Muslims in Ramadan, a difference that can be attributed to subjects' lack of experience of fasting as well as the amount of time spent fasting. A difficulty of interpretation in all these studies was that changes could be due to fasting and/or the length of sleep, which tends to decrease. These two factors were separated in the final experiment, an intervention study performed in the laboratory. This study compared effects of different durations of fasting (4, 8 or 16 h) upon a wide variety of measures (including subjective and objective assessments of performance, dehydration and responses to a short bout of exercise) - but with an unchanged amount of nocturnal sleep and daytime naps not allowed. Many of the negative effects observed in previous studies were present in this experiment also. These findings indicate that fasting was responsible for much of the change previously observed, though some effect of sleep loss, particularly if occurring on successive days (as would occur in Ramadan) cannot be excluded. One finding common to all studies was that tests of performance that had shown variations due to the combination of circadian influences, time awake and sleep loss in other experiments (including grip strength, the Stroop test and accuracy at throwing darts) seemed little affected. Possible reasons for these negative findings are discussed, together with further experiments to separate out effects of sleep loss and fasting, and the role of subjects' experience in studies of fasting. In addition, more detailed studies to investigate changes in sleep and the type and level of physical activities when fasting are proposed.

Cardiovascular disease is one of the largest killers in the UK representing 30% of all global deaths. The underlying processes of the disease are thought to begin in childhood. Whilst traditional risk factors of CV disease (e.g. hypertension, hyperlipidemia, obesity, smoking, stress and sedentary lifestyles) are becoming increasingly prevalent within the younger generation there remains the need for the establishment of earlier or "pre-clinical" markers of future CV disease risk or current atherosclerotic load such as left ventricular (LV) mass, diastolic function and carotid intima-media thickness( cIMT). Further, assessing the association of these markers to other risk factors and then determining the impact of physical activity (PA) interventions is warranted. Initially we assessed the impact of body composition, PA and cardiorespiratory (CR) fitness upon left ventricular LV mass, carotid-intima media thickness (cIMT) and LV diastolic function in 218 9-11 year old primary schoolchildren. Pubertal status was assessed through a maturity offset calculation. LV mass, cIMT, and LV diastolic function were assessed via ultrasound. Body mass index was assessed via anthropometry whilst fat mass [FM] and lean mass [LM] were determined via dual X-ray absorptiometry. Average 3-day PA was recorded via a uni-axial accelerometer and CR (VO₂peak) was determined from a graded treadmill test. Relationships were analysed using bivariate correlations and forced entry multiple regression. All children were classified as being below their peak height velocity. Together LM, FM, sex and moderate to vigorous (MV)PA accounted for 59% of the variance in LV mass with LM being the most important predictor (P<0.005). Sex, LM, FM and VO₂peak explained only 19% variance in cIMT and just 9% of the variance in LV diastolic function was accounted for by LM, FM blood pressure and sex. Data for MVPA had no significant relationship to any cardiovascular (CV) variables although was negatively correlated with FM. The strong association between LV mass and body composition likely represents normal growth. The limited shared variance between predictor variables and cIMT and LV diastolic function suggests that those pre-peak height velocity children in the current cohort who were overweight, inactive and unfit were not yet at an increased CV disease risk. Thus there is a window of opportunity for intervention programmes to be implemented that reduce CV disease risk before adolescence and adulthood. Following this, an exploratory trial was conducted to introduce the use of PA interventions in pre-pubertal children. Sixty-one 10-11 year old Liverpool primary school children volunteered and were randomly assigned by school to a STEX programme (2 x 60 min sessions per week at a heart rate of ~145 beats min⁻¹), a PASS programme (weekly physical activity tasks and pedometer challenges) and a control (CON; no intervention). Pre-clinical CV measures and body composition were measured before and after the 9-week intervention period. The primary outcome variable was cIMT, with LV mass, LV diastolic function, and body composition defined as secondary outcomes. Delta (Δ) scores were analysed by ANCOVA, with baseline scores as the covariate. For the primary outcome, the probability that the population effect of the intervention is at least as great as the pre-specified minimum clinically importance difference (MCID) was estimated, to evaluate clinical relevance. All participants met 75% compliance criteria for STEX and PASS. The effect of the STEX intervention (compared with CON) was a mean benefit of -0.018mm for average maximum cIMT (90% CI, -0.039 to 0.002mm), and -0.016mm for average mean cIMT (90 % CI, -0.040 to 0.008mm). The probability (% chances) that the true population effect of the STEX intervention would be clinically beneficial was 79% for average maximum and 71% for average mean cIMT. The PASS intervention did not result in clinically important effects, and no other substantial changes were observed for the secondary outcome variables. The relatively high probability of clinically beneficial effects of the STEX intervention suggests that a larger, "definitive" randomised trial with longer follow-up is warranted to define the effectiveness of the intervention more precisely. As a consequence the longer PA intervention study observed 152 children aged 9 to 10 years over 12 months. All of the echocardiographic, body composition, CR fitness and PA variables mentioned were assessed as previously discussed. Children were randomly assigned by school to an intervention group. Control (no intervention), PASS (as before except delivered during school hours to enhance compliance), high intensity physical activity (the same as STEX but renamed due to the addition of another structured exercise group) or fundamental movement skill ([FMS] 2x 60 min sessions per week of skill based activities). These interventions took place over a year period with participants being assessed at baseline, approximately mid-way through and post-test (52 weeks). Initial factorial ANOVA analysis comparing all 3 intervention groups and a control group before, during and after the 12 month intervention period, found limited statistically significant evidence for a positive impact of PA interventions compared to controls in pre-pubertal children. However, after adjusting for confounding variables in an ANCOVA analysis some sporadic benefits of PA interventions on CV variables were uncovered. An increase in LV mass over 12 months, after adjustment, was lower in the HIPA group compared to CON group (11.5 g; 90% CI, 2.0 to 21.0 g). This change was also lower in the FMS group compared to CON group (13.8 g; 90% CI, 4.6 to 23.1 g). The ANCOVA adjusted change scores for both mean and max cIMT were less in the intervention groups compared to CON group but only in the PASS group were these differences significant (P<0.05). PASS increased its mean cIMT (-0.014mm less than control (90% CI, -0.002 to -0.030)). Somewhat surprisingly the intervention programmes had no positive effect on CR fitness (indeed this decreased), PA measures and/or body composition over and above changes observed due to growth. This thesis has provided a unique insight into the 'pre-clinical' CV disease risk factors in pre-pubertal children and the impact of differing PA activity interventions with this group. Interestingly the research has shown that within this population overweight/obese, inactive low CR fit individuals are generally not at a higher CV disease risk than their aged matched 'healthier' counterparts. When PA interventions are introduced in the short term positive changes in cIMT were seen, however, this is not reciprocated in longer PA interventions possibly due to a larger maturation effect over 12 months. Interestingly year long interventions provide some attenuation of growth-related changes in CV disease risk factors but these changes are generally small and sporadic. It is suggested that further research over a longer period of time with more 'at risk' populations is needed. The PA interventions adopted achieved high attendance and compliance records and thus may be transferable out of the research process. It is interesting to also speculate that future research may not need to administer high impact activity, as previously thought, as some positive data was obtained in more general lifestyle interventions involving more knowledge transfer.

The menopause is associated with a deficiency of reproductive hormones, and accompanied by a significant loss of bone mass. This bone loss is accelerated within the first five years post-menopause. Muscle strength at this time would have important clinical implications for correcting imbalance and preventing falls. The aim of the studies within this thesis were to 1) determine the rate and time course of force loss of the quadriceps muscle group over 12 months in three groups of women with varying hormonal status 2) establish the role of oestrogen in this weakness and 3) investigate the effectiveness of hormone replacement therapy (HRT) in maintaining muscle function. The reliability of an isokinetic dynamometer and a strain gauge assembly was examined initially to determine the inherent variability of muscle function assessment. Strength of the knee extensors measured on the isokinetic dynamometer was deemed reliable in middle-aged women, although at 1.05 rad/s more practice trials were needed to attain peak torque. Measurements of the knee flexors were highly variable. Maximal voluntary isometric contractions were repeatable using the strain gauge system, for both the knee extensors and first dorsal interosseus (FOI) muscle. There was greater variability in force production generated from electrically stimulated contractions. Maximal strength of the knee extensors declined by 9.3-4.6 and I0.3?3.1% (mean?SE) for dynamic (1.05 radls) and isometric strength respectively over 9 months in hypoestrogenic post-menopausal women. There were no changes at higher angular velocities, or for handgrip strength. These results support the role of reproductive hormones in influencing force production, which is further endorsed by the observation that females on HRT did not experience a reduction in strength over this time. The force loss was significant only when the post-menopausal and HRT group were compared (p < 0.05). The postmenopausal group were within I to 3 years past the menopause, the time period in which bone loss is rapid. This rapid loss of strength would therefore be expected to level out, similarly to bone. The menopause is an oestrogen-deficient and progesterone-deficient endocrinopathy. It is not possible to identify which hormone, if not both, is responsible for these observed changes in strength. To explore the relationship between acute changes in oestrogen and progesterone and strength, maximal force production of the quadriceps and first dorsal interosseus (FOI) was measured across the menstrual cycle. Maximal strength of the quadriceps was lowest prior to the surge in luteinizing hormone (LH) and reached its peak mid-luteal, a difference of 12.6?4.3% (mean?SE). These changes were significantly different (p < O.OS). From these results, there does not appear to be a role of unopposed oestrogen influencing force production but the pattern of strength changes implicates progesterone. There were no corresponding fluctuations in strength of the FOI, which remained relatively stable across the menstrual cycle. The contractility and fatigue resistance of the quadriceps did not differ significantly between any phase (p > O.OS).The difficulty in isolating oestrogen during the menstrual cycle does not render this a good model to assess its effects upon force production. Maximal strength and fatiguability of the FDI were examined in young women undergoing in vitro fertilisation (IVF) treatment when acute, massive changes in oestrogen are induced. There were no differences in muscle function of the FDI when assessed under very low or high oestrogen changes (p > O.05). The independent effects of oestrogen upon muscle function were not demonstrated here. Hormone replacement therapy is the most efficacious treatment for preventing menopausally-related bone loss. The results from the longitudinal study suggest that HRT confers protection against muscle weakness as a consequence of ovarian failure. Whether HRT maintains or restores strength was examined in the FDI of post-menopausal women (n=9). The oestrogen only and oestrogen-progestogen phases were compared with baseline measurements. A positive change in strength was observed, although this did not reach significance (p < O.1). The increase in strength (15.2±20.6%) between baseline and the oestrogen-progestogen phase of HRT corroborates the involvement of progesterone in determining muscle function. The findings suggest that the menopause is associated with a loss of strength, prevented by the administration of HRT. Oestrogen alone does not influence force production, although progesterone is implicated. This has important ramifications in hysterectomised women who are prescribed preparations containing oestrogen only.

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.

Player's performance in competitive matches is partly determined by the systematic training programmes that they complete. The differences in the organisation of training may result in differences in the physiological stress placed on players. This study aimed to investigate the influence of training organisation on the physiological, metabolic and molecular responses to soccer-specific intermittent exercise in skeletal muscles. In Chapter 3, the physical demands of professional soccer training were examined by quantifying the physiological loads and work-rate profiles of elite players throughout the programmed pre-season and in-season training for a one week period. The physiological loads in pre-season were significantly higher than those in the in-season period (p < 0.05). Similar activity profiles were, however, observed during each training period irrespective of the time of the year. These findings demonstrate that pre- season training was more intensive than in-season training though these differences were not linked to changes in the activity patterns during sessions. Technical/tactical training seems to be an important component in increasing the physiological strain observed in pre-season training. This study also indicates that soccer training seems to elicit different demands to those associated with match-play. In Chapter 4, a laboratory-based soccer-specific training simulation (LSSTS) was devised on a motorized treadmill. Attempts were made to re-create both similar overall exercise intensities and patterns of discrete activity observed in training. The validity of this protocol was evaluated by comparing the physiological responses of professional players with those of healthy subjects who completed the LSSTS. Physiological measurements such as mean HR and % of HRmax associated with the simulation were similar to those obtained in the actual training session. These data suggest that the protocol is suitable in re-creating a soccer-specific training session in the laboratory. This protocol is, therefore, sufficient to use in investigations to study the physiological responses and the molecular adaptations of skeletal muscle to soccer-specific intermittent exercise. In Chapter 5, the effect of a single bout of soccer-specific intermittent exercise on metabolic stress and acute molecular responses associated with mitochondrial biogenesis was investigated in human skeletal muscle. The LSSTS was utilised as the sports-specific exercise protocol. The levels of blood metabolites and muscle glycogen were significantly altered during and after exercise (p < 0.05). Simulated soccer-specific training also acutely activated the expression of PGG-1a mRNA in human skeletal muscle (p < 0.05). There was, however, no significant change in the phosphorylation of AMPK and p38MAPK. This would suggest that the global effect of soccer-specific intermittent exercise on aerobic performance may be partly mediated by adaptations associated with mitochondrial biogenesis in skeletal muscle. ' In Chapter 6, the effect of prior soccer-specific training on the physiological, metabolic and molecular responses to a subsequent bout of soccer-specific intermittent exercise was evaluated. Two experimental trials (BETWEEN DA Y trial, one bout of soccer-specific intermittent exercise in a day Vs WITHIN DA Y trial, two consecutive bouts of soccer-specific intermittent exercise performed in a day) were completed on two separate occasions. There were significant increases in physiological responses during the second bout of exercise in the WITHIN DAY trial, compared to those obtained in the, BETWEEN DAY trial (p < 0.05). A more pronounced increase in NEFA and glycerol was observed in the WITHIN DAY trial compared with the BETWEEN DAY trial post-exercise following the second bout of exercise (p < 0.05). The expression of PGC-1a mRNA significantly increased following exercise compared to pre- and post-exercise values. There was, however, no difference in phosphorylation of AMPK and p38MAPK and the expression of PGC-1a mRNA between either trial. Based on these findings, it would seem that different approaches to training organisation may be more important for the acute physiotoqlca: responses to soccer-specific intermittent exercise than the molecular changes underpinning chronic adaptations.

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