The effect of the CYP1A2 -163 C\u3eA polymorphism on the metabolism of caffeine and effect on performance

Prior studies from our laboratory suggest that the -163 C \u3e A polymorphism of the Cytochrome P450 (CYP1A2) gene influences the ergogenic effect of caffeine. Although this polymorphism has been known to influence the inducibility of hepatic CYP1A2 and the rate of caffeine metabolism, levels of caffeine and/or metabolites have never been reported in these aforementioned studies (1, 12, 16). Thus, a mechanistic link between the polymorphism and the ergogenic effect of caffeine is lacking. The purpose of this study was to determine if the CYP1A2 polymorphism affected caffeine metabolism between the genotypes (AA homozygotes and C allele carriers). Twenty male subjects were recruited for this study. Subjects participated in two 3km cycling time trials with placebo (all-purpose flour) and caffeine (6mg/kg body weight anhydrous caffeine) supplementation. “Slow metabolizers” were characterized as possessing a “C” allele on the first intron of that gene (grouped AC heterozygotes, and CC homozygotes), and “fast metabolizers” were those who were homozygous for the A allele. C allele carriers had significantly higher serum caffeine after one hour (C allele carriers = 14.2 ± 1.8 ppm, AA homozygotes = 11.7 ± 1.7 ppm). While there was a main effect for caffeine ingestion on time trial performance, there was no caffeine x genotype interaction (C allele carriers: Placebo = 297 ± 20.8 sec, Caffeine = 292 ± 20 sec; AA homozygotes: Placebo = 318.3 ± 34.5 sec; Caffeine = 307.9 ± 21.9 sec). Results from this study suggest that C allele carriers have higher serum caffeine after one hour than AA homozygotes, consistent with the assertion that C allele carriers metabolize caffeine slower. These findings do not support a genetic influence on the ergogenic effect of caffeine in a 3km cycling trial

Mild Dehydration Led to Increased Difficulty Falling Asleep

Sleep is fundamental process that benefits health and overall quality of life which can be affected by various aspects of daily living such as dehydration. A study has yet to investigate the impacts of euhydration and mild dehydration on sleep. PURPOSE: The purpose of this study was to examine effects of euhydration, mild-dehydration, and ad libitum drinking on sleep. METHODS: Eighteen male participants (mean±SD; age, 23±4y; height, 175.8±5.7cm; weight, 80.1±9.7kg) reported to the laboratory with different hydration status for 4 consecutive mornings(Day 1, baseline; Day 2, euhydrated; Day 3, mild-dehydrated; Day 4, ad libitum drinking). Hydration status was monitored by first morning urine specific gravity (USG) and plasma osmolality. Sleepwas measured using the Karolinska sleep diary (KSD). RESULTS: USG (baseline, 1.024±0.006; euhydrated, 1.018±0.007; mild-dehydrated, 1.030±0.003; ad libitum, 1.021±0.008, pCONCLUSION: When subjects were mildly dehydrated, sleep duration was longer while it was more difficult to fall asleep. More research is necessary, but the results of this study suggest it may be important to maintain euhydration to fall asleep easier

The Impact of Menstrual Cycle Phase and Sex on Outcomes Related to Hydration Interventions

Archival abstract submitte

Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance

This project was designed to assess the effects of time of day and training status on the benefits of caffeine supplementation for cycling performance. Twenty male subjects (Age, 25 years; Peak oxygen consumption, 57 mL·kg−1·min−1) were divided into tertiles based on training levels, with top and bottom tertiles designated as ‘trained’ (n = 7) and ‘untrained’ (n = 7). Subjects completed two familiarization trials and four experimental trials consisting of a computer-simulated 3-km cycling time trial (TT). The trials were performed in randomized order for each combination of time of day (morning and evening) and treatment (6mg/kg of caffeine or placebo). Magnitude-based inferences were used to evaluate all treatment effects. For all subjects, caffeine enhanced TT performance in the morning (2.3% ± 1.7%, ‘very likely’) and evening (1.4% ± 1.1%, ‘likely’). Both untrained and trained subjects improved performance with caffeine supplementation in the morning (5.5% ± 4.3%, ‘likely’; 1.0% ± 1.7%, ‘likely’, respectively), but only untrained subjects rode faster in the evening (2.9% ± 2.6%, ‘likely’). Altogether, our observations indicate that trained athletes are more likely to derive ergogenic effects from caffeine in the morning than the evening. Further, untrained individuals appear to receive larger gains from caffeine in the evening than their trained counterparts

Mild Dehydration Identification Using Machine Learning to Assess Autonomic Responses to Cognitive Stress

The feasibility of detecting mild dehydration by using autonomic responses to cognitive stress was studied. To induce cognitive stress, subjects (n = 17) performed the Stroop task, which comprised four minutes of rest and four minutes of test. Nine indices of autonomic control based on electrodermal activity (EDA) and pulse rate variability (PRV) were obtained during both the rest and test stages of the Stroop task. Measurements were taken on three consecutive days in which subjects were “wet” (not dehydrated) and “dry” (experiencing mild dehydration caused by fluid restriction). Nine approaches were tested for classification of “wet” and “dry” conditions: (1) linear (LDA) and (2) quadratic discriminant analysis (QDA), (3) logistic regression, (4) support vector machines (SVM) with cubic, (5) fine Gaussian kernel, (6) medium Gaussian kernel, (7) a k-nearest neighbor (KNN) classifier, (8) decision trees, and (9) subspace ensemble of KNN classifiers (SE-KNN). The classification models were tested for all possible combinations of the nine indices of autonomic nervous system control, and their performance was assessed by using leave-one-subject-out cross-validation. An overall accuracy of mild dehydration detection was 91.2% when using the cubic SE-KNN and indices obtained only at rest, and the accuracy was 91.2% when using the cubic SVM classifiers and indices obtained only at test. Accuracy was 86.8% when rest-to-test increments in the autonomic indices were used along with the KNN and QDA classifiers. In summary, measures of autonomic function based on EDA and PRV are suitable for detecting mild dehydration and could potentially be used for the noninvasive testing of dehydration

Availability of a Flavored Beverage and Impact on Children’s Hydration Status, Sleep, and Mood

Euhydration remains a challenge in children due to lack of access and unpalatability of water and to other reasons. The purpose of this study was to determine if the availability/access to a beverage (Creative Roots®) influences hydration in children and, therefore, sleep quality and mood. Using a crossover investigation, 46 participants were randomly assigned to a control group (CON) or an intervention group and received Creative Roots® (INT) for two-week periods. We recorded daily first morning and afternoon urine color (Ucol), thirst perception, and bodyweight of the two groups. Participants reported to the lab once per week and provided first morning urine samples to assess Ucol, urine specific gravity (USG), and urine osmolality (Uosmo). Participants also completed the questionnaires Profile of Mood States-Adolescents (POMS-a) and Pittsburgh Sleep Quality Index (PSQI). Dependent t-tests were used to assess the effects of the intervention on hydration, mood, and sleep quality. Uosmo was greater and Ucol was darker in the control group (mean ± SD) [Uosmo: INT = 828 ± 177 mOsm·kg−1, CON = 879 ± 184 mOsm·kg−1, (p = 0.037], [Ucol:INT = 5 ± 1, CON = 5 ± 1, p = 0.024]. USG, POMS-a, and PSQI were not significant between the groups. At-home daily afternoon Ucol was darker in the control group [INT = 3 ± 1, CON = 3 ± 1, p = 0.022]. Access to Creative Roots® provides a small, potentially meaningful hydration benefit in children. However, children still demonstrated consistent mild dehydration based on Uosmo, despite consuming the beverage