The influence of a CYP1A2 polymorphism on the ergogenic effects of caffeine

<p>Abstract</p> <p>Background</p> <p>Although caffeine supplementation improves performance, the ergogenic effect is variable. The cause(s) of this variability are unknown. A (C/A) single nucleotide polymorphism at intron 1 of the cytochrome P450 (CYP1A2) gene influences caffeine metabolism and clinical outcomes from caffeine ingestion. The purpose of this study was to determine if this polymorphism influences the ergogenic effect of caffeine supplementation.</p> <p>Methods</p> <p>Thirty-five trained male cyclists (age = 25.0 ± 7.3 yrs, height = 178.2 ± 8.8 cm, weight = 74.3 ± 8.8 kg, VO₂max = 59.35 ± 9.72 ml·kg^-1·min^-1) participated in two computer-simulated 40-kilometer time trials on a cycle ergometer. Each test was performed one hour following ingestion of 6 mg·kg^-1of anhydrous caffeine or a placebo administered in double-blind fashion. DNA was obtained from whole blood samples and genotyped using restriction fragment length polymorphism-polymerase chain reaction. Participants were classified as AA homozygotes (N = 16) or C allele carriers (N = 19). The effects of treatment (caffeine, placebo) and the treatment × genotype interaction were assessed using Repeated Measures Analysis of Variance.</p> <p>Results</p> <p>Caffeine supplementation reduced 40 kilometer time by a greater (<it>p </it>< 0.05) magnitude in AA homozygotes (4.9%; caffeine = 72.4 ± 4.2 min, placebo = 76.1 ± 5.8 min) as compared to C allele carriers (1.8%; caffeine = 70.9 ± 4.3 min, placebo = 72.2 ± 4.2 min).</p> <p>Conclusions</p> <p>Results suggest that individuals homozygous for the A allele of this polymorphism may have a larger ergogenic effect following caffeine ingestion.</p

No effect of short-term amino acid supplementation on variables related to skeletal muscle damage in 100 km ultra-runners - a randomized controlled trial

Background: The purpose of this study was to investigate the effect of short-term supplementation of amino acids before and during a 100 km ultra-marathon on variables of skeletal muscle damage and muscle soreness. We hypothesized that the supplementation of amino acids before and during an ultra-marathon would lead to a reduction in the variables of skeletal muscle damage, a decrease in muscle soreness and an improved performance. Methods: Twenty-eight experienced male ultra-runners were divided into two groups, one with amino acid supplementation and the other as a control group. The amino acid group was supplemented a total of 52.5 g of an amino acid concentrate before and during the 100 km ultra-marathon. Pre- and post-race, creatine kinase, urea and myoglobin were determined. At the same time, the athletes were asked for subjective feelings of muscle soreness. Results: Race time was not different between the groups when controlled for personal best time in a 100 km ultra-marathon. The increases in creatine kinase, urea and myoglobin were not different in both groups. Subjective feelings of skeletal muscle soreness were not different between the groups. Conclusions: We concluded that short-term supplementation of amino acids before and during a 100 km ultra-marathon had no effect on variables of skeletal muscle damage and muscle soreness

EFFECTS OF TRAINING AND SEX ON EXPIRATORY FLOW LIMITATION PREVALENCE AND SEVERITY IN YOUTH CYCLISTS

Will Burton1, Sarah Ridgeway1, Katherine Cox1, Joshua Smith2, Nicholas Luden1, Michael Saunders, FACSM1, Stephanie Kurti1. 1Human Performance Laboratory, James Madison University, Harrisonburg, VA. 2Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN. BACKGROUND: Expiratory flow limitation (EFL) poses a potential mechanical limitation of the pulmonary system during maximal exercise in endurance-trained athletes, but the prevalence in females and males of pubertal age is not well understood. The purpose of this investigation was to assess EFL presence in endurance-trained (ET) youth males and females compared to a recreationally active (RA) control group. METHODS: Youth ET male (n=12, 16.3 ± 1.0 y), RA male (n=12, 17.6 ± 2.2 y), ET female (n=9, 15.8 ± 1.1 y), and RA female (n=10, 16.8 ± 1.6 y) subjects completed an incremental exercise test to exhaustion on a cycle ergometer to determine peak oxygen consumption (VO2peak). Maximal flow volume loops (MFVL) were performed pre- and post-exercise to assess forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, forced expiratory flow between 25% and 75% of FVC (FEF25-75% of FVC) and peak expiratory flow (PEF). Inspiratory capacity (IC) maneuvers were performed the last 20 seconds of every stage. EFL was quantified as the percentage of the expiratory tidal volume that overlapped with the MFVL. RESULTS: EFL prevalence was higher in ET males and females at VO2peak (18/21 subjects; 11/12 males, 7/9 females) compared to RA male and female subjects (7/22 subjects; 5/12 males, 2/10 females) (p \u3c 0.05). ET females had significantly greater EFL severity than RA females at maximal exercise (57.0 ± 36.4%, 13.3 ± 32.2%, respectively, p = 0.013), while there was no difference in EFL severity between ET and RA males (p = 0.473). ET males also had significantly greater EFL severity at maximal exercise compared to RA males (75.0 ± 32.9%, 29.7 ± 40.4%, p = 0.007). There was no difference in the prevalence and severity of flow-limitation between ET males and females or between RA males and females (p’s \u3e 0.05). CONCLUSIONS: Both ET male and ET female cyclists demonstrated greater prevalence and severity of EFL at maximal exercise than respective same-sex RA subjects of similar age, height, and lung size. Further research should be conducted to determine whether EFL may limit exercise performance in this population and whether EFL exists into adulthood

Temporal and Spatial Distribution Patterns of Potentially Pathogenic Vibrio spp. at Recreational Beaches of the German North Sea

The number of reported Vibrio-related wound infections associated with recreational bathing in Northern Europe has increased within the last decades. In order to study the health risk from potentially pathogenic Vibrio spp. in the central Wadden Sea, the seasonal and spatial distribution of Vibrio vulnificus, Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio cholerae were investigated at ten recreational beaches in this area over a 2-year period. V. alginolyticus and V. parahaemolyticus were found to be omnipresent all year round in the study area, while V. vulnificus occurrence was restricted to summer months in the estuaries of the rivers Ems and Weser. Multiple linear regression models revealed that water temperature is the most important determinant of Vibrio spp. occurrence in the area. Differentiated regression models showed a species-specific response to water temperature and revealed a particularly strong effect of even minor temperature increases on the probability of detecting V. vulnificus in summer. In sediments, Vibrio spp. concentrations were up to three orders of magnitude higher than in water. Also, V. alginolyticus and V. parahaemolyticus were found to be less susceptible towards winter temperatures in the benthic environment than in the water, indicating an important role of sediments for Vibrio ecology. While only a very small percentage of tested V. parahaemolyticus proved to be potentially pathogenic, the presence of V. vulnificus during the summer months should be regarded with care