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The General Organization for Technical Education and Vocational Training, Riyadh, Saudi Arabia, has developed a special feeding program for the students at its institutions. The effects of this program on the nutritional and health status of these students have not been evaluated yet, and since no published dietary research has been performed on Technical and Vocational young adult male students, the present work was undertaken to investigate the nutritional status of this community in Riyadh, Kingdom of Saudi Arabia. After a pilot survey, it was decided to use a selfcompleted questionnaire combined with personal interview to investigate the nutritional status of 690 students randomly selected from the study population. Dietary data was collected by two methods: usual weekly intakes "diet history" and actual daily intakes "diet diary". The nutrient intakes were calculated using the unilever Dietary Analysis Program (UNIDAP). The statistical Package for the social Science (SPSS/PC+) was employed to analyse the data; statistical significance of relationships between certain sets of data was determined by chi-square analysis. Some general factors affecting the nutritional status of these students were identified, their nutritional habits and attitudes were investigated, and the average daily intakes of energy, the macronutrients, and selected micronutrients were calculated. The main results of this study shows that the majority of the study population are adolescent, moderately active individuals, and have lower than the standard range of the Body Mass Index; anaemia is the most stated health problem; meal-skipping and eating between meals are common habits amongst the students. Regarding nutrient intake, there was an energy, polyunsaturated fat, and vitamin C deficiency; adequate intake of saturated fat, dietary fibre, retinol, and zinc; more than adequate intake of protein, total fat, cholesterol, thiamin, riboflavin, calcium, and iron. Recommendations are given which aim to improve the nutrition of technical and vocational students.

Dietary restriction (DR) is the only known nutritional manipulation that can increase both lifespan and healthspan in a variety of species. Underlying these increases are improvements in metabolic health and reductions in cancer incidence. Despite these physiological improvements, the regulation of skeletal muscle mass is extremely sensitive to alterations in nutrients [reviewed in (Sharples et al., 2015)] and as such has been reported to reduce regenerative potential and increase atrophy in skeletal muscle cells and myotubes. Interestingly, the activation of Sirtuin1 (SIRT1) has been reported during DR and its reduction abrogates lifespan extension. Importantly, SIRT1 activation via resveratrol treatment has been indicated to be important in the presence of inflammatory stress (TNF-α) (Saini et al., 2012). Resveratrol supplementation has also improved survival and regeneration of skeletal muscle cells as well in muscle cell remodelling following oxidative stress (Bosutti and Degens, 2015). We therefore sought to create an in-vitro physiological model of DR by mimicking levels of glucose in the circulation and interstitium in-vivo in response to DR (Chapter 3) as well as optimising the activation and inhibition of SIRT1 using resveratrol and SIRT1 inhibitor, EX-527 respectively (Chapter 4). With our ultimate aim to investigate the potential role and mechanisms of the activation/inhibition of SIRT1 in ameliorating the degenerative/atrophic effect of DR in both differentiating myoblasts (Chapter 5) and mature myotubes (Chapter 6). Indeed, in Chapter 3 we present two models of reduced glucose; one reduced (medium/ MED) and the other blocked (LOW) differentiation and myotube hypertrophy. The former represented circulatory glucose blood levels (MED 1.13 g/L or 6.25 mM) and the latter interstitial represented glucose levels (LOW 0.56 g/L or 3.12 mM) of rodents under DR. In Chapter 4 we also suggest that within the in vitro muscle cell model, activation/inhibition of SIRT1 phosphorylation (western blot analysis) was thought to be most effective at 10 μM of resveratrol and 100 nM of EX-527 respectively. In chapter 5, we observed that resveratrol treatment did not improve fusion when administered to differentiating myoblasts. Resveratrol did however evoke increases in myotube hypertrophy under normal glucose conditions. Importantly resveratrol enabled improved myotube hypertrophy over an acute 24 h period when administered to existing mature myotubes in low glucose environments. If this finding translates to whole organisms and human populations it could provide healthspan improvements via reductions in fragility associated with loss of muscle mass in individuals undergoing dietary restriction. After this 24 h period resveratrol was unable to reduce myotube atrophy and the myotubes continued to atrophy, suggestive of a need for repeated resveratrol treatment to enable continued protection against muscle atrophy under low glucose conditions. SIRT1 activation increased Myogenic regulatory factor 4 (MRF4) gene expression under LOW glucose conditions which was associated with the observed improvements in myotube size at 24 h. Whereas, SIRT1 activation via resveratrol treatment in normal glucose conditions modulated increased gene expression of Myosin heavy chain 7 (MYHC7) coding for the slow isoform while inhibition of SIRT1 (EX-527) lead to reductions in gene expression of MYHC 1, 2 and 4, coding for faster IIx, IIa, IIb isoforms respectively. Perhaps suggesting that elevated SIRT1 was important in the activation of genes coding for slower myosin heavy chain isoforms. Furthermore, while SIRT activation via resveratrol did modulate increases in IGF-I gene expression, it did not appear to modulate energy sensing AMP activated protein kinase (AMPK) vs. growth related Protein 70 S6 Kinase (p70S6K) signalling pathways. However, SIRT1 inhibition increased AMPK activity in both low and normal glucose with corresponding mean reductions in p70S6K in normal glucose conditions. This indicates that perhaps normal SIRT1 activity was required for appropriate AMPK activation, which may therefore prevent the suppression of p70S6K and the corresponding reductions in myotube size observed in SIRT1 inhibitor conditions. Furthermore, during low glucose induced myotube atrophy resveratrol reduced gene expression of the negative regulator of muscle mass, myostatin and protein degradative ubiquitin ligase enzyme, MUSA1. Overall, SIRT1 activation via a single dose of resveratrol appears to have a role in acutely negating the effect of low glucose induced myotube atrophy and promoting myotube hypertrophy when glucose is readily available.

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.

Cardiovascular disease (CVD) is the leading cause of global mortality, with the incidence of cardiovascular related pathologies remaining a public health burden. CVD encompasses pathologies of the vascular tree and heart, including, for example, peripheral artery disease, coronary heart disease and ischaemic stroke. Atherosclerosis is the primary pathological process leading to CVD and is characterised by a multifactorial pathophysiology that first manifests in the vascular endothelium. Termed endothelial dysfunction, this early marker of atherosclerosis has become a focus of interest for identifying individuals at risk of a profound cardiovascular insult, particularly arising from lifestyle choices such as physical inactivity and calorie-rich diets. Dietary interventions have received increasing attention in recent years as inexpensive strategies to potentially combat the ever-increasing global burden of CVD. A high dietary flavonoid intake is associated with a reduction in CVD risk and several studies have revealed a strong, inverse relation between the regular intake of tea, a major source of dietary flavonoids, and CVD risk. Tea has demonstrated improved conduit artery endothelial function and glucose handling in both healthy individuals and in those with overt CVD. However, the effects of tea on the microvasculature and cerebrovasculature are not yet understood, particularly in relation to lifestyle factors. The primary aim of this thesis was to explore the impact of tea ingestion on peripheral and cerebral micro- and macrovascular function in humans. In an initial methodological study, the day-to-day reproducibility of thermally stimulated cutaneous microvascular function was assessed. Fifteen, healthy males (28 ± 5 yrs, BMI 25 ± 2 kg/m2) attended two experimental trials 2-7 days apart. During each trial, baseline and maximal thermally stimulated forearm skin responses were examined simultaneously at four sites on the dominant forearm using laser Doppler flowmetry (LDF). The following heating protocols were adopted: 1. Rapid 39°C (0.5°C/5-s), 2. Rapid 42°C (0.5°C/5-s) 3. Gradual 42°C (0.5°C/2-min 30-s) and 4. Slow 42°C (0.5°C/5-min). The coefficient of variation (CV) was calculated for absolute flux, cutaneous vascular conductance (CVC; flux/mean arterial pressure, MAP) and CVC expressed as a percentage of maximal CVC at 44°C (%CVCmax) at three different time points; baseline (33°C), plateau (39/42°C) and maximal (44°C). Reproducibility of baseline flux, CVC and %CVCmax was 17-29% across all protocols. During the plateau, Rapid, Gradual and Slow 42°C demonstrated a reproducibility of 13-18% for flux and CVC and 5-11% for %CVCmax. However, Rapid 39°C demonstrated a lower reproducibility for flux, CVC and %CVCmax (21%). Reproducibility at 44°C was 12-15% for flux and CVC across all protocols. The good-to-moderate reproducibility of the Rapid, Gradual and Slow 42°C protocols supported their (simultaneous) use to assess peripheral microvascular function. The aim of Chapter 5 was to examine the acute (2-hour) cutaneous vascular responses to local skin heating following ingestion of black tea in a healthy adult population. Twenty healthy participants (58 ± 5 yrs, BMI 26 ± 4 kg/m2, 9 men) attended two experimental trials (tea, placebo), 7-days apart in a randomised, controlled, double-blind, cross-over design. Participants ingested a single dose of 200 ml black tea or placebo, followed by assessment of forearm cutaneous microvascular function using LDF and three distinct local skin heating protocols to distinguish between axon- and endothelium-dependent vasodilation: 1. Rapid 42°C, 2. Rapid 39°C and 3. Gradual 42°C. On the contralateral arm, full-field laser perfusion imaging (FLPI) was used to assess forearm cutaneous microvascular function during Gradual 42°C. Data were analysed as CVC and %CVCmax. Rapid local heating to 39°C or 42°C demonstrated no effect of tea for flux, CVC or %CVCmax (all P > 0.05). Gradual local heating to 42°C, however, produced a higher skin blood flow following black tea ingestion for absolute CVC (P=0.04) when measured by LDF, and higher absolute flux (P < 0.001) and CVC (P < 0.001) measured with FLPI. No effect of tea was found for %CVCmax when assessed by either LDF or FLPI. The aim of the study outlined in Chapter 6 was to examine the effect of daily green tea consumption (equivalent to 6 cups/day) on changes in peripheral vascular function and glucose handling after a 7-day ‘unhealthy’ lifestyle in healthy males. Twelve healthy males (29 ± 6 yrs, BMI 25 ± 2 kg/m2) underwent two periods of 7-days ‘unhealthy’ lifestyle (UL) comprising of combined physical activity reduction (-50% steps per day) and high fat, high carbohydrate overfeeding (+50% kcal per day, comprising 65% fat) in a randomised, controlled, double-blind, cross-over design. Each intervention period was separated by a 2-week washout. During each 7-day UL-period, participants ingested three doses of an active green tea drink (UL-Tea) or a placebo drink (UL-Placebo) per day at regular intervals. Participants attended the laboratory before and after each 7-day intervention (a total of 4 visits). During each visit the following were examined: mean arterial blood pressure (MAP), dominant forearm cutaneous microvascular function using LDF and local heating protocols 1. Rapid 42°C, 2. Rapid 39°C and 3. Gradual 42°C, macrovascular function using brachial artery and femoral artery endothelium-dependent function via flow-mediated dilation (FMD), carotid artery vasoreactivity to the cold pressor test (CAR%), cerebrovascular function via CO2 reactivity and dynamic cerebral autoregulation, and insulin sensitivity and glucose handling through a mixed-meal (1200kcal, comprising 60% carbohydrates, 33% fat and 7% protein) tolerance test. Linear mixed models (main effects of intervention and time) were used to examine the impact of the lifestyle intervention (pre vs post) and green tea ingestion (UL-Tea vs UL-Placebo). Body mass demonstrated a slight increase following both UL-Tea and UL-Placebo (P > 0.05). MAP was increased after UL-Placebo, whereas it was reduced after UL-Tea (P=0.06). LDF responses to rapid local heating demonstrated non-significant reductions in CVC following UL-Placebo but no difference following UL-Tea (P > 0.05), with a significant interaction of time*condition*temperature observed following Gradual 42°C (P=0.02). Brachial artery FMD was not different pre vs post or between UL-Placebo and UL-Tea (P > 0.05), whereas femoral artery FMD decreased after UL-Placebo, which was prevented during UL-Tea (P < 0.001). CAR% decreased following UL-Placebo, which was prevented during UL-Tea (P=0.04). CO2 reactivity and dynamic cerebral autoregulation demonstrated no differences between UL-Placebo and UL-Tea or over time. Postprandial glucose was increased after UL-Placebo, whereas a reduction in postprandial glucose occurred after UL-Tea (P=0.03). Postprandial insulin levels were higher after UL-Placebo, consistent with insulin resistance, whereas following UL-Tea the insulin response was reduced and demonstrated an interaction of time*condition (P < 0.001). The aim of Chapter 7 was to examine the effect of acute oral (-)-epicatechin ingestion on cerebrovascular function in healthy adults. Seven healthy males (32 ± 13 yrs, BMI 25 ± 1 kg/m2) attended two experimental trials ((-)-epicatechin and placebo) 7-days apart in a randomised, controlled, double-blind, cross-over design. Participants underwent baseline assessment of cerebrovascular function using transcranial Doppler ultrasound (TCD), comprising CO2 reactivity to hypercapnia and dynamic cerebral autoregulation via squat-stand manoeuvres at 0.10 Hz and 0.05 Hz. / Following completion of the baseline measures, participants immediately consumed an oral dose of the test product (2 x 50 mg capsules of (-)-epicatechin or 2 capsules of colour-matched placebo) together with a glass of water, following which participants relaxed in the laboratory. 2-hours post-ingestion repeat measures of cerebrovascular function were performed. Linear mixed models (main effects of condition and time) examined the differences between (-)-epicatechin and placebo interventions (pre vs post) on cerebrovascular function. No differences were observed at pre vs post baseline for middle cerebral artery velocity (MCAv) or MAP (all P > 0.05). There were no differences in the cerebrovascular responses to CO2 or dynamic autoregulation between (-)-epicatechin and placebo. The findings from this thesis suggest that, firstly, use of simultaneous skin local heating protocols provides a valuable means of interrogating the cutaneous microvessels for mechanistic insight in intervention studies. Secondly, current findings evidence improved cutaneous microvascular function following acute black tea consumption. Furthermore, the research work undertaken in this thesis provides important insight into the effects of tea consumption on peripheral (micro- and macro-) vascular function and insulin sensitivity, particularly its abrogative effects on lifestyle-induced vascular impairments. However, the effects of tea consumption on the cerebrovasculature remain uncertain. Overall, based on the current findings, tea consumption presents a simple, inexpensive, non-pharmacological cardioprotective strategy to help combat the ever-increasing global burden of CVD.

Rugby is a complex, high-intensity, intermittent, collision sport with emphasis placed on players possessing high lean body-mass and low body-fat. After an 8-12 week pre-season focused on physiological adaptations, emphasis shifts towards optimizing competitive performance and recovery through periodising player’s diets and training. In Chapter 4 the physiological demands and nutritional intakes of 45 elite rugby players were assessed during a pre-season through a battery of strength and conditioning tests, quantification of training demands using global positioning system (GPS), and two 24-hour diet recalls. Mean weekly distance covered during training was 9774 ± 1404 and 11585 ± 1810 m with a total mean weekly session RPE (sRPE) of 3398 ± 335 and 2944 ± 410 arbitrary units (AU) for forwards and backs respectively. Mean daily energy intake was 14.8 ± 1.9 and 13.3 ± 1.9 MJ, carbohydrate (CHO) intake was 3.3 ± 0.7 and 4.14 ± 0.4 g·kg-1 body mass, protein intake was 2.52 ± 0.3 and 2.59 ± 0.6 g·kg-1 body mass, and fat intake was 1.0 ± 0.3 and 0.95 ± 0.3 g·kg-1 body mass for forwards and backs respectively. Markers of physical performance (1-RM strength, speed, and repeated sprint tests) and anthropometry (body fat, and estimated lean mass) significantly improved in all players, despite players’ self-selecting a ‘low’ CHO ‘high’ protein diet. It may be speculated therefore that ‘low’ CHO ‘high’ protein intakes are appropriate to fuel the pre-season, although whether these intakes are sufficient to fuel the in-season is unknown. Once the demands of the pre-season were established, the next aim of the thesis was to examine if requirements changed during the playing season, as well as quantifying energy expenditure. In Chapter 5 in-season training load using GPS and sRPE, alongside six-day assessments of energy intake (EI) and energy expenditure (EE) was measured in 44 elite Rugby Union players. Mean weekly distance covered was 7827 ± 954 m and 9572 ± 1233 m with a total mean weekly sRPE of 1776 ± 355 and 1523 ± 434 AU for forwards and backs, respectively. Mean daily EI was 16.6 ± 1.5 and 14.2 ± 1.2 MJ, and EE was 15.9 ± 0.5 and 14 ± 0.5 MJ for forwards and backs respectively. Mean CHO intake was 3.5 ± 0.8 and 3.4 ± 0.7 g·kg-1 body mass, protein intake was 2.7 ± 0.3 and 2.7 ± 0.5 g·kg-1 body mass, and fat intake was 1.4 ± 0.2 and 1.4 ± 0.3 g·kg-1 body mass for forwards and backs respectively. All players who completed the food diary self-selected a ‘low’ CHO ‘high’ protein diet during the early part of the week which increased in the days leading up to a match. EI and EE followed an inverse trend, with expenditure exceeding intake during the first four-days of the training week and then reversed in the day leading up to competition with intake exceeding expenditure. Despite this, mean EI exceeded EE which alongside no micronutrient deficiencies, suggest that the current dietary practices of these elite rugby players seem sufficient to fuel training during the in-season, providing energy intake and CHO are increased leading up to a match. Given that intakes reported in this study are still below recommended CHO intake for elite athletes (Burke et al 2011), however, it is still possible that such intakes are not optimal for match day performance. Given that in Chapters 4 and 5 it was found that elite Rugby players appear to deliberately select a low carbohydrate intake, it was deemed important to assess match-play glycogen demands following a low (the amount self selected in chapter 4) and higher (the amount self selected leading in to competition in chapter 5) carbohydrate diet. Therefore, in Chapter 6 the metabolic and physiological demands of rugby competition was assessed in 16 professional Rugby League players following either a 6g·kg (HCHO) or 3g·kg (LCHO) CHO diet for 36-hours. Muscle biopsy and blood was collected, alongside monitoring internal and external load through GPS and heart rate. Mean distance covered was 93.7 ± 12.4 and 89.4 ± 9.8 m·min-1 in the first, and 85.3 ± 13.1 and 86.9 ± 9.7 m·min-1 in the second half for HCHO and LCHO conditions respectively. Mean %HRpeak was 82.9 ± 6.1 and 81.9 ± 7.2 % in the first and 82.5 ± 7.5 and 78.4 ± 10.5 % in the second half for HCHO and LCHO conditions respectively. Mean muscle glycogen was 448.6 ± 50.8 and 444.2 ± 81.1 mmol·kg d·w-1 pre-game, and 243.4 ± 42.5 and 297.7 ± 130.5 mmol·kg d·w-1 post-game for HCHO and LCHO conditions respectively. Results demonstrate that a competitive RL match can result in ~40% muscle glycogen depletion and that match-day performance variables did not differ between conditions. It was postulated that an absolute amount of ~600 g CHO consumed 36-hours pre-match is a recommended strategy for rugby league players, although optimal dietary strategies to refuel after rugby competition are unknown. The final aim of the thesis was to examine if the current post exercise CHO guidelines are appropriate for rugby players. In Chapter 7 the magnitude of muscle glycogen repletion after consuming an immediate, or delayed re-feed post Rugby League Match Simulation Protocol (RLMSP) was assessed in 16 university rugby league players using muscle biopsy and blood letting techniques. Muscle glycogen very likely increased 48-h post-simulation (272 ± 97 cf. 416 ± 162 mmol·kg-1d.w.) after an immediate re-feed, but changes were unclear (283 ± 68 cf. 361 ± 144 mmol·kg-1d.w.) after a delayed re-feed. Creatine Kinase (CK) almost certainly increased by 77.9 ± 25.4 % (0.75 ± 0.19) post-simulation for all players. Player Load (8 ± 0.7 AU) and %HRpeak (83 ± 4.9 %) were consistent with professional RL match-play. Time to exhaustion performance test revealed no difference between conditions. This study found that simulated RL match-play elicits lower muscle glycogen utilisation (21 cf. 40 %) despite similar player load and metabolic demands to a professional RL match. This may be attributed to the difficulties of replicating extensive structural damage and physical exertion from collisions during a simulation. It was also found that substantial muscle glycogen resynthesis was possible in the immediate dietary re-feed group despite evidence of muscle damage via increased blood proteins, indicating that with appropriate feeding strategies it is possible to replenish a damaged muscle. Taken together, this thesis has characterized the training demands and energy balance of elite rugby players during the pre-season and in-season, alongside quantifying the metabolic demands of elite rugby match-play, and the most appropriate strategies to load and replenish muscle glycogen around such exercise. Future studies must now further titrate these studies and assess muscle glycogen utilisation over a number of games whilst assessing the glycogen content of individual muscle fibre types.

The prevalence of maternal obesity is on the increase, compromising both maternal and foetal health. Previous intervention studies have been designed to limit the amount of gestational weight gain but in the absence of UK guidelines relating to optimum weight change in obese pregnancies and the negative experiences of obese women with regard to previous weight loss attempts it is reasonable to ask whether this is the most effective approach. It has been demonstrated that maternal dietary intake can impact on gestational weight gain and birth weight but there is little in the way of research into the impact that quality of diet has on outcomes. Aims: To measure the quality of maternal dietary intake and weight change against pregnancy and birth outcomes and to explore and gain insight into the lived experience of obese pregnant women with a view to informing guidelines. Methods: Pregnant women with a BMI≥35kg/m2 were recruited from antenatal clinic and asked to complete 3 day food diaries at 16,28 and 36 weeks gestation, The diaries were verified using a food atlas and analysed using Microdiet. A subset of women were then followed up and interviewed regarding their lived experience of obesity. Results: The women’s dietary intake deteriorated over the duration of pregnancy and there were significant associations between some micronutrients and pregnancy and birth outcomes. Women with a BMI 35-39.9kg/m2 were most likely to gain weight. Conclusion: The dietary intake of obese pregnant women is an important predictor of pregnancy and birth outcomes and it was demonstrated that the quality of diet significant deteriorated over the duration of pregnancy. Interventions designed to increase the quality of diet are urgently required.

This work addresses the use of microwave techniques to determine quality parameters in cured meat. The first approach is online monitoring of weight loss in the meat curing process, which is a significant measurement for the meat industry because the weight loss is used as a method of tracking the curing process. Currently, weight loss is measured by using ordinary weighing scales, which is a time-consuming and impractical technique. Thus, a novel method is required to simplify the process by implementing an online monitoring technique. In this work, a set of microwave sensors were modelled using High Frequency Structure Simulation Software and then constructed and tested. Weight loss of the sample and change in the S11-parameter illustrated a strong linear relationship (R2 > 0.98). The prediction model then was developed using the Partial Least Squares method, which exhibited a good capability of microwave sensors to predict weight loss, with R2p (prediction) = 0.99 and root mean square error of prediction (RMSEP) = 0.41. The second approach is to determine water activity (aw) in cured meat, which is the parameter that describes available water for microorganisms and influences different chemical reactions in the product. For the cured meat industry, aw is the only moisture related measurement that is an accepted Hazard Analysis and Critical Control Point plan. This is important for safety reasons, but also for energy optimisation since curing requires controlled continuous temperature and humidity. Currently, aw is being measured by the meat industry using commercially available instruments, which have limitations, namely being destructive, expensive and time-consuming. Few attempts to develop non-destructive methods to predict aw have used X-ray systems (namely Computed Tomography), Near Infrared (NIR) and Hyperspectral Imaging (HSI). Although the techniques provided promising results, they are expensive, impractical and not commercially available for the meat industry. The results from the microwave sensors demonstrated a linear relationship (R2 = 0.75, R2 = 0.86 and R2 = 0.91) between the S11 and aw at 2.4 GHz, 5 GHz and 7 GHz, respectively. The prediction model exhibited a good capability of the sensors to predict aw (R2p = 0.91 and RMSEP = 0.0173).

Low childhood physical activity levels, and high paediatric overweight and obesity levels, carry a considerable burden to health including cardiometabolic disease, low fitness, and reduced psychosocial well-being. Numerous school- based physical activity interventions have been conducted with varied success. This thesis therefore aimed to develop and investigate the effectiveness of the Children's Health, Activity and Nutrition: Get Educated! (CHANGE!) project, which was a school-based curriculum intervention to promote healthy lifestyles using an educational focus on physical activity and healthy eating. The purpose of the formative study (Study 1) was to elicit subjective views of children, their parents, and teachers about physical activity to inform the design of the CHANGE! intervention programme. Analyses revealed that families have a powerful and important role in promoting health-enhancing behaviours. Involvement of parents and the whole family is a strategy that could be significant to ~ncrease children's physical activity levels. There is large variation in the cut-points used to define moderate physical activity (MPA), vigorous physical activity (VPA) and sedentary time, which impacts on accurate estimation of physical activity levels. The purpose of Study 2 was to test a field-based protocol using intermittent activities representative of children's physical activity behaviours, to generate behaviourally valid, population-specific cut-points for sedentary behaviour, MPA and VPA. These cut-points were subsequently applied to CHANGE! to investigate changes in physical activity (Study 3). The CHANGE! intervention resulted in positive changes to body size and VPA outcomes after follow-up. The effects were strongest among those sociodemographic groups at greatest risk of poor health status. Further work is required to test the sustained effectiveness of this approach in the medium and long-term. Further, the development of an inexpensive and replicable field- based protocol to generate behaviourally valid and population-specific accelerometer cut-points may improve classification of physical activity levels in children, which could enhance subsequent intervention and observational studies.

The work described in this thesis addresses two questions relating to benefits of dietary omega-3 fatty acids (n-3 LCPUFA). Accretion of research knowledge indicates that adequate n-3 LCPUFA intakes may be instrumental in maintaining good health throughout life, including in the optimisation of cardiovascular health. Sources of n-3 LCPUFA traditionally include fish oils but concern regarding long-term sustainability of fish stocks has led to investigation of alternative sources. Krill oil, obtained from the crustacean Euphausia superba, contains n-3 fatty acids as phospholipids and triglycerides, astaxanthin and related carotenoid pigments, and has been proposed as a more effective alternative than triglyceride oils. Some foods rich in n-3-LCPUFA, including prawns, also contain cholesterol; concern regarding possible adverse health effects of such dietary cholesterol has led to public health advice to limit intake of these potentially beneficial foodstuffs. These questions are addressed in two food intake studies in male volunteers by monitoring markers of cardiovascular health, food intake and biochemical markers of compliance. Firstly, prawns and a white fish control were compared for effects on lipoprotein profiles and other markers. Dietary supplementation with 225 g prawns daily for 4 weeks was associated with a decrease in ApoB of 7.8mg/dL compared an increase (+2.4 mg/dL) for the white fish control. Participants with BMI > 25 kg/m2 also showed a reduction in plasma TAG (0.17 mmol/L) compared with baseline following prawn intake; those receiving the control showed an increase in plasma TAG (0.30 mmol/L), a decrease in HDL-C, and increases in VLDL-C and sdLDL-C. No overall adverse effect was found for prawns compared with processed white fish. Secondly, effects were compared of fish oil and krill oil on cardiometabolic profiles of a cohort of men with metabolic syndrome, using anthropometric measurements, biochemical markers of cardiovascular health and assessments of food intake. Krill oil and fish oil at the doses used showed no overall difference in effect on MetS markers after 6 weeks; correlations between magnitude of reduction and baseline measurement were observed in both groups for TAG, fasting glucose, NEFA and sdLDL after 3 weeks on both supplements, and for glucose and cholesterol after 6 weeks of fish oil. Comparison of analytical methods was also undertaken during both studies; use of a point-of-care system using capillary blood correlated well with plasma biochemistry using venous blood, while the Hirano method for sdLDL measurement correlated favourably with more labour-intensive centrifugation techniques. Limitations of the methods used are discussed, and proposals put forward for future work, including improving compliance through the use of newly emerging technologies such as metabolomics.