The impact of N-3 pufa ingestion on metabolic, molecular and epigenetic responses to a short-term high-fat diet

Obesity is widely considered a primary risk factor for type 2 diabetes (T2D). However, less is known about the early adaptive responses to short-term periods of high-fat energy excess (HFEE). Previous reports detailing whole-body adaptation to fat and energy oversupply are equivocal, perhaps, in part, owing to use of different experimental protocols, varying durations of dietary manipulation and participant cohorts with individuals of varying characteristics. In addition to use of different dietary protocols between studies, alterations in functional end-point measures due to the type of dietary fat consumed warrants consideration. Daily n-3 PUFA intake, commonly obtained from pelagic fish oil (FO) consumption, has been shown to positively associate with insulin sensitivity in epidemiological studies and thus may be a useful dietary strategy for slowing insulin resistance development. Chapter 2 of this thesis extends previous literature by demonstrating that 6 d HFEE (150 % habitual energy intake; 60 % of energy from fat) does not clearly alter whole- body insulin sensitivity, irrespective of FO consumption. However, investigation of metabolism at the tissue level, as presented in Chapter 3 of this thesis, offers insight into a potential tissue-specific level of regulation that precedes whole-body regulation. Skeletal muscle insulin signalling protein (e.g. protein kinase B (PKB)) activity, levels of certain ceramide species, and AMPK α2 activity were altered following HFEE and may explain the early maladaptive responses to short-term HFEE. Moreover, FO intake as 10 % of total fats mediated some of these molecular Sophie Wardle: Ph.D. Thesis ii responses, including PKB and AMPK α2 activity, reflecting possible functional effects of FO at the subcellular level. Regulation of these metabolic / molecular responses at both the tissue and whole- body level can be explained, in part, by genetic predisposition, environmental influence and more recently epigenetics, including microRNAs (miRNAs). In Chapter 4, we characterised the plasma and skeletal muscle miRNA responses to HFEE and oral glucose ingestion. We demonstrate transient changes in levels of certain miRNAs following oral glucose ingestion in both tissue types and in response to HFEE in skeletal muscle. However, no significant correlations between basal plasma and skeletal muscle miRNA levels were observed, suggesting that our candidate plasma miRNAs may be co-ordinating functional changes in other tissue types. Plasma miR- 145-5p and skeletal muscle miR-204-5p predicted a significant proportion of the variance in mean whole-body insulin sensitivity change in response to HFEE. These data indicate that these miRNAs may be useful biomarkers of insulin resistance development following HFEE. A constraint of this thesis is that all conclusions are made within the context of statistically unaltered insulin sensitivity. Therefore, future investigations of diet- induced maladaptation should consider establishing a time course of insulin resistance development in response to HFEE, or use different study populations. Populations that are more susceptible to T2D development, e.g., overweight, sedentary individuals would be of particular interest. These data would aid development of a working model of diet-induced insulin resistance that has more direct application to T2D progression and extends the data presented herein

Plasma microRNA levels differ between endurance and strength athletes

Aim: MicroRNAs (miRNAs) are stable in the circulation and are likely to function in inter-organ communication during a variety of metabolic responses that involve changes in gene expression, including exercise training. However, it is unknown whether differences in circulating-miRNA (c-miRNA) levels are characteristic of training modality. Methods: We investigated whether levels of candidate c-miRNAs differ between elite male athletes of two different training modalities (n = 10 per group) - endurance (END) and strength (STR) - and between these groups and untrained controls (CON; n = 10). Fasted, non-exercised, morning plasma samples were analysed for 14 c-miRNAs (miR-1, miR-16-2, miR-20a-1, miR-21, miR-93, miR-103a, miR-133a, miR-146a, miR-192, miR-206, miR-221, miR-222, miR-451, miR-499). Moreover, we investigated whether c-miRNA levels were associated with quantitative performance-related phenotypes within and between groups. Results: miR-222 was present at different levels in the three participant groups (p = 0.028) with the highest levels being observed in END and the lowest in STR. A number of other c-miRNAs were present at higher levels in END than in STR (relative to STR, ± 1 SEM; miR-222: 1.94 fold (1.73-2.18), p = 0.011; miR-21: 1.56 fold (1.39-1.74), p = 0.013; miR-146a: 1.50 fold (1.38-1.64), p = 0.019; miR-221: 1.51 fold (1.34-1.70), p = 0.026). Regression analyses revealed several associations between candidate c-miRNA levels and strength-related performance measures before and after adjustment for muscle or fat mass, but not following adjustment for group. Conclusion: Certain c-miRNAs (miR-222, miR-21, miR-146a and miR-221) differ between endurance- and resistance-trained athletes and thus have potential as useful biomarkers of exercise training and / or play a role in exercise mode-specific training adaptations. However, levels of these c-miRNAs are probably unrelated to muscle bulk or fat reserves

Menstrual disturbances in British Servicewomen: A cross-sectional observational study of prevalence and risk factors

Female athletes are at increased risk of menstrual disturbances. The prevalence of menstrual disturbances in British Servicewomen and the associated risk factors is unknown. All women under 45 years in the UK Armed Forces were invited to complete a survey about demographics, menstrual function, eating and exercise behaviors, and psychological well-being. 3,022 women participated; 18% had oligomenorrhoea or amenorrhoea in the last 12 months, 25% had a history of amenorrhoea, and 14% had delayed menarche. Women who sleep ≥ 8 h were at a lower risk of a history of amenorrhoea than women who sleep ≤ 5 h [odds ratio (95% confidence intervals) = 0.65 (0.48, 0.89), p = 0.006]. Women who completed > 10 days of field exercise in the last 12 months were at higher risk of a history of amenorrhoea than women completing no field exercise [1.45 (1.13, 1.85), p = 0.004]. Women at high risk of an eating disorder (FAST score >94) were at higher risk of oligomenorrhoea or amenorrhoea [1.97 (1.26, 3.04), p = 0.002] and history of amenorrhoea [2.14 (1.63, 2.79), p < 0.001]. Women with symptoms of anxiety or depression were at higher risk of a history of amenorrhoea [1.46 (1.20, 1.77) and 1.48 (1.22, 1.79), p < 0.001]. British Servicewomen had a similar prevalence of menstrual disturbances to some endurance athletes. Eating disorders, sleep behaviors, and management of mental health, provide targets for protecting health of the reproductive axis

Nutrition and Physical Activity in British Army Officer Cadet Training Part 2 - Daily Distribution of Energy and Macronutrient Intake

Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure (EE). Thirteen participants (seven women) were monitored during three discrete periods of military training for nine days on-camp (CAMP), five days’ field exercise (FEX) and nine days of a mixture of the two (MIX). Dietary intake was measured using researcher-led food weighing and food diaries and EE was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4600kcal·d-1) and women (3500kcal·d-1) during CAMP (men: -16%; women -9%), FEX (men: -33%; women: -42%) and MIX (men and women both -34%). Carbohydrate intake of men and women were below guidelines (6g·kg·d-1) during CAMP (men: -10%; women: -9%), FEX (men: -18%; women: -37%), and MIX (men: -3%; women: -39%), respectively. Protein intake was above guidelines (1.2kcal·kg·d-1) for men and women during CAMP (men: 48%; women: 39%) and MIX (men: 9%; women: 3%), but below guidelines during FEX (men: -13%; women: -27%). Energy and macronutrient intake during CAMP centred around mealtimes with a discernible sleep/wake cycle for EE. During FEX, energy and macronutrient intake were individually variable and EE was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimise performance and adaptations during military training

Beyond change scores: Employing an improved statistical approach to analyze the impact of entry fitness on physical performance during British Army basic training in men and women

AbstractThe aim was to use a robust statistical approach to examine whether physical fitness at entry influences performance changes between men and women undertaking British Army basic training (BT). Performance of 2 km run, seated medicine ball throw (MBT) and isometric mid‐thigh pull (MTP) were assessed at entry and completion of Standard Entry (SE), Junior Entry‐Short (JE‐Short), and Junior Entry‐Long (JE‐Long) training for 2350 (272 women) recruits. Performance change was analyzed with entry performance as a covariate (ANCOVA), with an additional interaction term allowing different slopes for courses and genders (p &lt; 0.05). Overall, BT courses saw average improvements in 2 km run performance (SE: −6.8% [−0.62 min], JE‐Short: −4.6% [−0.43 min], JE‐Long: −7.7% [−0.70 min]; all p &lt; 0.001) and MBT (1.0–8.8% [0.04–0.34 m]; all p &lt; 0.05) and MTP (4.5–26.9% [6.5–28.8 kg]; all p &lt; 0.001). Regression models indicate an expected form of “regression to the mean” whereby test performance change was negatively associated with entry fitness in each course (those with low baseline fitness exhibit larger training improvements; all interaction effects: p &lt; 0.001, &gt; 0.006), particularly for women. However, when matched for entry fitness, men displayed considerable improvements in all tests, relative to women. Training courses were effective in developing recruit physical fitness, whereby the level of improvement is, in large part, dependent on entry fitness. Factors including age, physical maturity, course length, and physical training, could also contribute to the variability in training response between genders and should be considered when analyzing and/or developing physical fitness in these cohorts for future success of military job‐task performance

Nutrition and Physical Activity during British Army Officer Cadet Training: Part 1 - Energy Balance and Energy Availability

Military training is characterised by high daily energy expenditures (EE) which are difficult to match with energy intake (EI) potentially resulting in negative energy balance (EB) and low energy availability (EA). The aim of this study was to quantify EB and EA during British Army Officer Cadet (OC) training. Thirteen (seven women) OCs (mean ± SD: age 24 ± 3 years) volunteered to participate. EB and EA were estimated from EI (weighing of food and food diaries) and EE (doubly-labelled water) measured in three periods of training; nine days on-camp (CAMP), a five-day field exercise (FEX) and a nine-day mixture of both (MIX). Variables were compared by condition and gender with a repeated measures ANOVA. Negative EB was greatest during FEX (-2197 ± 455 kcal·d-1) compared with CAMP (-692 ± 506 kcal·d-1; p<0.001) and MIX (-1280 ± 309 kcal·d-1; p<0.001). EA was greatest in CAMP (23 ± 10 kcal·d-1) compared with FEX (1 ± 16 kcal·d-1; p=0.002) and MIX (10 ± 7 kcal·d-1; p=0.003), with no apparent difference between FEX and MIX (p=0.071). Irrespective of condition, there were no apparent differences between gender in EB (p=0.375) or EA (p=0.385). These data can be used to inform evidenced-based strategies to manage EA and EB during military training and enhance the health and performance of military personnel

Learning to Eat Vegetables in Early Life: The Role of Timing, Age and Individual Eating Traits

Vegetable intake is generally low among children, who appear to be especially fussy during the pre-school years. Repeated exposure is known to enhance intake of a novel vegetable in early life but individual differences in response to familiarisation have emerged from recent studies. In order to understand the factors which predict different responses to repeated exposure, data from the same experiment conducted in three groups of children from three countries (n = 332) aged 4–38 m (18.9±9.9 m) were combined and modelled. During the intervention period each child was given between 5 and 10 exposures to a novel vegetable (artichoke puree) in one of three versions (basic, sweet or added energy). Intake of basic artichoke puree was measured both before and after the exposure period. Overall, younger children consumed more artichoke than older children. Four distinct patterns of eating behaviour during the exposure period were defined. Most children were “learners” (40%) who increased intake over time. 21% consumed more than 75% of what was offered each time and were labelled “plate-clearers”. 16% were considered “non-eaters” eating less than 10 g by the 5th exposure and the remainder were classified as “others” (23%) since their pattern was highly variable. Age was a significant predictor of eating pattern, with older pre-school children more likely to be non-eaters. Plate-clearers had higher enjoyment of food and lower satiety responsiveness than non-eaters who scored highest on food fussiness. Children in the added energy condition showed the smallest change in intake over time, compared to those in the basic or sweetened artichoke condition. Clearly whilst repeated exposure familiarises children with a novel food, alternative strategies that focus on encouraging initial tastes of the target food might be needed for the fussier and older pre-school children

Reinterpretation of LHC Results for New Physics: Status and recommendations after Run 2

We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data