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    Effect of caffeine ingestion on aspects of endurance performance and cognition in CYP1A2 hetrozygous A/C male recreational athletes : a thesis presented in partial fulfilment for the requirements of a Master of Science in Sport and Exercise Science at Massey University, Albany, New Zealand
    (Massey University, 2016) Southward, Kyle
    Background: Globally, caffeine is the most widely accessible psychoactive drug and has been shown to improve endurance performance as well as aspects of cognition, mood and perceptual responses during exercise. However, the ergogenic effects of caffeine between individuals are variable, and the cause of this variability is unknown. The CYP1A2 gene is known to mediate caffeine metabolism and has been suggested as a contributor to the variability of the ergogenic effects of caffeine. Purpose: To investigate the effects of CYP1A2 genotype on exercise performance (10 km time trial), sleep, mood, cognition and perceptual responses following caffeine ingestion in adult male recreational athletes. Methods: 16 recreationally trained athletes (age = 26.9 ± 7.93 y; weight = 77.00 ± 9.04 kg) volunteered for this study. Participants completed a familiarisation session at least one week before the first trial and a saliva sample was collected for testing of the participants’ CYP1A2 genotype. Participants completed two trials one week apart in a randomised double-blind placebo-controlled cross-over design. Participants were asked to abstain from caffeine ingestion and keep a food diary for 24 h prior to the trial. Participants wore an actigraph, and completed a sleep diary and Leeds Sleep Evaluation Questionnaire (LSEQ) every day for the two week duration of the trials starting 3 days before the first trial and ending 3 days after the second trial. The main trial consisted of a set of pre- and post-ingestion measures which included leg power by vertical jump height (squat jump – SJ; countermovement jump – CMJ), leg strength by maximal voluntary concentric and eccentric contraction of the knee extensors (isokinetic dynamometer), perceptual (feeling scale – FS; felt arousal scale – FAS), mood (profile of mood states – POMS), cognition (digit vigilance – DV; Corsi blocks – CB; rapid visual information processing – RVIP) and heart rate. Pre- and post-ingestion urine, saliva and blood samples were also collected for analysis of caffeine metabolism and genotype. Following completion of pre-ingestion measures, participants consumed a capsule containing either anhydrous caffeine (6 mg∙kg-1) or placebo (maltodextrin) and were instructed to rest quietly for 50 min. Following post-ingestion measures, participants completed a 10-km time trial run. Perceptual measures (FS and FAS) including ratings of perceived exertion (RPE) were recorded every 2.5 km and heart rate was recorded every 1 km. A venous blood sample and saliva sample was collected at 5 km and 10 km. At completion of the 10-km time trial all post-ingestion measures were repeated, followed by another 50 min rest period. After the second 50 min rest period the participants completed the perceptual, mood and cognitive measures and further blood, urine and saliva samples were collected. Participants returned 24 and 48 h post-ingestion to repeat all post-ingestion measures and another blood, urine and saliva sample was collected. This protocol was then repeated 1 week later for the alternate treatment (placebo or caffeine). The effect of treatment (caffeine, placebo) and the interaction effect of treatment x time were assessed using a repeated measures ANOVA. A student’s t-test was used to measure differences between Leeds sleep evaluation questionnaire (LSEQ) and actigraph data. Results: Fourteen of sixteen participants were heterozygous A/C CYP1A2 for the CYP1A2 genotype and therefore results based on genotypes could not be compared as originally intended. Plasma caffeine, paraxanthine and theophylline concentrations were all elevated following caffeine ingestion (P < 0.05) peaking at 10-km, 1 hour after the 10-km run and 24 hours post caffeine ingestion respectively. Caffeine did not significantly improve 10-km run times. Eccentric leg strength but not concentric leg strength was improved following caffeine ingestion (P < 0.05). Squat jump height but not countermovement jump height was improved following caffeine ingestion (P < 0.05). Digit vigilance reaction times were decreased significantly following caffeine ingestion (P < 0.05) and a trend of decreased rapid visual information processing (RVIP) reaction times were seen (P < 0.1), however, no improvements in the accuracy during cognitive tests were seen following caffeine ingestion. A trend of increased heart rate (P < 0.1) during exercise was observed following caffeine ingestion, but no significant differences in heart rate before and after exercise were observed. Conclusions: While no overall, significant improvements in run time occurred following caffeine ingestion, 11 of 14 participants had a faster run time following caffeine ingestion compared to placebo. Caffeine, rather than the metabolites of caffeine, is likely the main cause of any observed ergogenic effects following caffeine ingestion as the improvements in reaction times, mood and endurance performance occurred when plasma caffeine concentration was elevated but plasma caffeine metabolite concentrations were low. It was found that caffeine ingestion improves endurance performance and reaction times during cognitive tasks. Taken together, the pharmacokinetics of the caffeine and caffeine metabolite peaks suggest that for athletes with the A/C CYP1A2 genotype ingestion of caffeine 1.5 – 2 h prior to an event may be more beneficial for endurance performance compared to the usual recommendations of taking caffeine 1 h prior to exercise. Keywords: caffeine, endurance exercise, CYP1A2, performance, genetics
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    Effect of leucine-protein high-carbohydrate post-exercise nutrition on subsequent performance and the protein regulated genomic and signalling events governing adaptive remodelling : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science, Massey University, Albany, New Zealand
    (Massey University, 2010) Thomson, Jasmine Sarah; Thomson, Jasmine Sarah
    Recovery from prolonged endurance exercise requires fuel replenishment and ultrastructure repair to restore cellular homeostasis; and improvement requires adaptive remodelling. Timing nutrient intake to closely follow exercise may be advantageous to recovery and subsequent performance by facilitating the adaptive processes stimulated by exercise. The objective of this research was to firstly determine if leucine-enriched protein feeding after hard training improved subsequent performance, and secondly to explore the candidate means by which protein-rich post-exercise nutrition mediates recovery, primarily transcriptomic and signalling mechanisms. Study 1 Ten male cyclists ingested leucine-enriched protein-carbohydrate (0.1/0.4/1.2/0.2 g∙kg-1∙h-1 leucine/protein/carbohydrate/fat) or isocaloric high-carbohydrate control (0.06/1.6/0.2 g∙kg-1∙h-1) meals following 2-2.5 h high-intensity interval training on 3 consecutive days. Cyclists performed a repeat-sprint performance test 39 h after training, and markers of physiological recovery and mood state were examined. Study 2 Eight male cyclists ingested protein (0.4/1.2/0.2 g∙kg-1∙h-1 protein/carbohydrate/fat) or isocaloric high-carbohydrate control (0.03/1.6/0.2 g∙kg-1∙h-1) beverages following a single 1.75 h high-intensity interval cycling bout. Muscle tissue samples were collected from the vastus lateralis before exercise, 3-h and 48-h post-exercise. The transcriptome response was assessed by Illumina microarray, candidate gene expression by real time RT-PCR; and phospho-protein signalling by Western blot. Leucine-enriched feeding increased mean sprint power by 2.5% (99% confidence limits, ±3.1%; P = 0.013) and reduced overall tiredness during sprints by 13% (90% confidence limits, ±9.2%). Serum creatine kinase was 19% (90% confidence limits, ±18%) lower than control, but difference in lactate dehydrogenase and muscle pain were trivial and unclear. In the second study, protein-carbohydrate feeding led to moderate and very large increases in cell signalling to translation; mTOR, 4E-BP1 and RPS6 phosphorylation by 3-h. Bioinformatics analysis indicates protein ingestion effects the transcriptome response involved in immune/inflammatory processes, tissue development (extracellular matrix, cytoskeletal, and scarcomere remodelling), and metabolism consistent with increased fatty acid oxidation, compared to control. Post-exercise protein and carbohydrate coingestion during a period of hard training enhances subsequent high-intensity endurance performance and may reduce membrane disruption in comparison to high-carbohydrate feeding. Furthermore, the mechanism responsible for protein-nutrition mediated adaptation may be through enhancing protein translation and fine-tuning the gene expression profile induced by exercise.