Non-targeted metabolomics in sport and exercise science

Metabolomics incorporates the study of metabolites that are produced and released through physiological processes at both the systemic and cellular level. Biological compounds at the metabolite level are of paramount interest in the sport and exercise sciences, although research in this field has rarely been referred to with the global ‘omics terminology. Commonly studied metabolites in exercise science are notably within cellular pathways for ATP production such as glycolysis (e.g. pyruvate and lactate), β-oxidation of free fatty acids (e.g. palmitate) and ketone bodies (e.g. β-hydroxybutyrate). Non-targeted metabolomic technologies are able to simultaneously analyse the large numbers of metabolites present in human biological samples such as plasma, urine and saliva. These analytical technologies predominately employ nuclear magnetic resonance spectroscopy and chromatography coupled to mass spectrometry. Performing experiments based on non-targeted methods allows for systemic metabolite changes to be analysed and compared to a particular physiological state (e.g. pre/post-exercise) and provides an opportunity to prospect for metabolite signatures that offer beneficial information for translation into an exercise science context, for both elite performance and public health monitoring. This narrative review provides an introduction to non-targeted metabolomic technologies and discusses current and potential applications in sport and exercise science

Adaptive changes in the neuronal proteome: mitochondrial energy production, endoplasmic reticulum stress, and ribosomal dysfunction in the cellular response to metabolic stress

Impaired energy metabolism in neurons is integral to a range of neurodegenerative diseases, from Alzheimer’s disease to stroke. To investigate the complex molecular changes underpinning cellular adaptation to metabolic stress, we have defined the proteomic response of the SH-SY5Y human neuroblastoma cell line after exposure to a metabolic challenge of oxygen glucose deprivation (OGD) in vitro. A total of 958 proteins across multiple subcellular compartments were detected and quantified by label-free liquid chromatography mass spectrometry. The levels of 130 proteins were significantly increased (P<0.01) after OGD and the levels of 63 proteins were significantly decreased (P<0.01) while expression of the majority of proteins (765) was not altered. Network analysis identified novel protein–protein interactomes involved with mitochondrial energy production, protein folding, and protein degradation, indicative of coherent and integrated proteomic responses to the metabolic challenge. Approximately one third (61) of the differentially expressed proteins was associated with the endoplasmic reticulum and mitochondria. Electron microscopic analysis of these subcellular structures showed morphologic changes consistent with the identified proteomic alterations. Our investigation of the global cellular response to a metabolic challenge clearly shows the considerable adaptive capacity of the proteome to a slowly evolving metabolic challenge

Gastrointestinal tract size, total-tract digestibility, and rumen microflora in different dairy cow genotypes

peer-reviewedThe superior milk production efficiency of Jersey (JE) and Jersey × Holstein-Friesian (JE × HF) cows compared with Holstein-Friesian (HF) has been widely published. The biological differences among dairy cow genotypes, which could contribute to the milk production efficiency differences, have not been as widely studied however. A series of component studies were conducted using cows sourced from a longer-term genotype comparison study (JE, JE × HF, and HF). The objectives were to (1) determine if differences exist among genotypes regarding gastrointestinal tract (GIT) weight, (2) assess and quantify whether the genotypes tested differ in their ability to digest perennial ryegrass, and (3) examine the relative abundance of specific rumen microbial populations potentially relating to feed digestibility. Over 3 yr, the GIT weight was obtained from 33 HF, 35 JE, and 27 JE × HF nonlactating cows postslaughter. During the dry period the cows were offered a perennial ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF than for JE and JE × HF. When expressed as a proportion of body weight (BW), JE and JE × HF had a heavier GIT weight than HF. In vivo digestibility was evaluated on 16 each of JE, JE × HF, and HF lactating dairy cows. Cows were individually stalled, allowing for the total collection of feces and were offered freshly cut grass twice daily. During this time, daily milk yield, BW, and dry matter intake (DMI) were greater for HF and JE × HF than for JE; milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ among the 3 genotypes. Intake capacity, expressed as DMI per BW, tended to be different among treatments, with JE having the greatest DMI per BW, HF the lowest, and JE × HF being intermediate. Production efficiency, expressed as milk solids per DMI, was higher for JE than HF and JE × HF. Digestive efficiency, expressed as digestibility of dry matter, organic matter, N, neutral detergent fiber, and acid detergent fiber, was higher for JE than HF. In grazing cows (n = 15 per genotype) samples of rumen fluid, collected using a transesophageal sampling device, were analyzed to determine the relative abundance of rumen microbial populations of cellulolytic bacteria, protozoa, and fungi. These are critically important for fermentation of feed into short-chain fatty acids. A decrease was observed in the relative abundance of Ruminococcus flavefaciens in the JE rumen compared with HF and JE × HF. We can deduce from this study that the JE genotype has greater digestibility and a different rumen microbial population than HF. Jersey and JE × HF cows had a proportionally greater GIT weight than HF. These differences are likely to contribute to the production efficiency differences among genotypes previously reported

THE IMPACT OF ESSENTIAL AMINO ACID SUPPLEMENTS ENRICHED WITH L-LEUCINE ON APPETITE AND ENERGY INTAKE IN ELDERLY WOMEN

Rationale: Inadequate protein intake (PI), the main source of essential amino acids (EAAs), and reduced appetite are contributing factors to age-related sarcopenia. The satiating effects of dietary protein may negatively affect energy intake (EI), thus there is a need to explore alternative strategies to facilitate PI without compromising appetite and subsequent EI. Methods: Elderly women completed two experiments (EXP1&2) where they consumed either a Bar (B, 135 kcal) or a Gel (G, 114 kcal), rich in EAAs (7.5 g, 40% L-Leucine), or nothing [control (C)]. In EXP1, subjects (n=10, 68±5 years, mean±SD) consumed B, G or C with appetite sensations and appetite-related hormonal responses monitored for 1h, followed by consumption of an ad libitum breakfast (ALB). In EXP2, subjects (n=11, 69±5 years) ingested B, G or C alongside an ALB. Results: In EXP1, EI at ALB was not different (P=0.674) between conditions (282±135, 299±122, 288±131 kcal for C, B and G respectively). However, total EI was significantly higher in B and G compared to C after accounting for the energy content of the supplements (P<0.0005). Analysis revealed significantly higher appetite Area under the Curve (AUC) (P<0.007), a tendency for higher acylated ghrelin AUC (P=0.087), and significantly lower pancreatic polypeptide AUC (P=0.02) in C compared with B and G. In EXP2, EI at ALB was significantly higher (P=0.028) in C (306±122 kcal) compared to B (245±135 kcal) and G (254±118 kcal). However, total EI was significantly higher in B and G after accounting for the energy content of the supplements (P<0.007). Conclusion: Supplementation with either the bar or gel increased total energy intake whether consumed 1h before or during breakfast. This may represent an effective nutritional means for addressing protein and total energy deficiencies in elderly women

From 'reckless' to 'mindful' in the use of outcome data to inform service-level performance management: perspectives from child mental health.

PublishedJournal ArticleThis is an open access article.

Test-meal palatability is associated with overconsumption but better represents preceding changes in appetite in non-obese males

Single course ad libitum meals are recommended for the assessment of energy intake within appetite research. This represents the first investigation of the comparative sensitivity of two single course ad libitum meals designed to differ in palatability. Two experiments were completed using a preload study design. All protocols were identical except for the energy content of the preloads (Experiment one: 579kJ and 1776kJ; Experiment two: 828kJ and 4188kJ). During each experiment, 10 healthy men completed four experimental trials constituting a low or high energy preload beverage, a 60 min intermeal interval, and consumption of a pasta-based or porridge-based ad libitum meal. Appetite ratings were measured throughout each trial and palatability was assessed after food consumption. Preload manipulation did not influence appetite (P=0.791) or energy intake (P=0.561) in experiment one. Palatability and energy intake were higher for the pasta meal than the porridge meal in both experiments (palatability P≤0.002; energy intake P≤0.001). In experiment two, consumption of the high energy preload decreased appetite (P=0.051) and energy intake (P=0.002). Energy compensation was not significantly different between pasta and porridge meals (P=0.172) but was more strongly correlated with preceding changes in appetite at the pasta meal (r=-0.758; P=0.011) than the porridge meal (r=-0.498; P=0.143). The provision of a highly palatable pasta-based meal produced energy intakes that were more representative of preceding appetite ratings but the moderately palatable porridge-based meal produced more ecologically valid energy intakes. Ad libitum meal selection and design may require a compromise between sensitivity and ecological validity

The effect of moderate versus severe simulated altitude on appetite, gut hormones, energy intake and substrate oxidation in men

Acute exposure to high altitude (>3500m) is associated with marked changes in appetite regulation and substrate oxidation but the effects of lower altitudes are unclear. This study examined appetite, gut hormone, energy intake and substrate oxidation responses to breakfast ingestion and exercise at simulated moderate and severe altitudes compared with sea-level. Twelve healthy males (mean±SD; age 30±9years, body mass index 24.4±2.7kg.m-2) completed in a randomised crossover order three, 305 minute experimental trials at a simulated altitude of 0m, 2150m (~15.8% O2) and 4300m (~11.7% O2) in a normobaric chamber. Participants entered the chamber at 8am following a 12h fast. A standardised breakfast was consumed inside the chamber at 1h. One hour after breakfast, participants performed a 60 minute treadmill walk at 50% of relative V̇O2max. An ad-libitum buffet meal was consumed 1.5h after exercise. Blood samples were collected prior to altitude exposure and at 60, 135, 195, 240 and 285 minutes. No trial based differences were observed in any appetite related measure before exercise. Post-exercise area under the curve values for acylated ghrelin, pancreatic polypeptide and composite appetite score were lower (all P<0.05) at 4300m compared with sea-level and 2150m. There were no differences in glucagon-like peptide-1 between conditions (P=0.895). Mean energy intake was lower at 4300m (3728±3179kJ) compared with sea-level (7358±1789kJ; P=0.007) and 2150m (7390±1226kJ; P=0.004). Proportional reliance on carbohydrate as a fuel was higher (P=0.01) before breakfast but lower during (P=0.02) and after exercise (P=0.01) at 4300m compared with sea-level. This study suggests that altitude-induced anorexia and a subsequent reduction in energy intake occurs after exercise during exposure to severe but not moderate simulated altitude. Acylated ghrelin concentrations may contribute to this effect