The Influence of Caffeine Expectancies on Simulated Soccer Performance in Recreational Individuals

Caffeine (CAF) has been reported to improve various facets associated with successful soccer play, including gross motor skill performance, endurance capacity and cognition. These benefits are primarily attributed to pharmacological mechanisms. However, evidence assessing CAF’s overall effects on soccer performance are sparse with no studies accounting for CAF’s potential psychological impact. Therefore, the aim of this study was to assess CAF’s psychological vs. pharmacological influence on various facets of simulated soccer performance. Utilising a double-dissociation design, eight male recreational soccer players (age: 22 ± 5 years, body mass: 78 ± 16 kg, height: 178 ± 6 cm) consumed CAF (3 mg/kg/body mass) or placebo (PLA) capsules, 60 min prior to performing the Loughborough Intermittent Shuttle Test (LIST) interspersed with a collection of ratings of perceived exertion (RPE), blood glucose and lactate, heart rate and performing the Loughborough Soccer Passing Test (LSPT). Whole-body dynamic reaction time (DRT) was assessed pre- and post- LIST, and endurance capacity (TLIM) post, time-matched LIST. Statistical analysis was performed using IBM SPSS (v24) whilst subjective perceptions were explored using template analysis. Mean TLIM was greatest (p < 0.001) for synergism (given CAF/told CAF) (672 ± 132 s) vs. placebo (given PLA/told PLA) (533 ± 79 s). However, when isolated, TLIM was greater (p = 0.012) for CAF psychology (given PLA/told CAF) (623 ± 117 s) vs. pharmacology (given CAF/told PLA) (578 ± 99 s), potentially, via reduced RPE. Although DRT performance was greater (p = 0.024) post-ingestion (+5 hits) and post-exercise (+7 hits) for pharmacology vs. placebo, psychology and synergism appeared to improve LSPT performance vs. pharmacology. Interestingly, positive perceptions during psychology inhibited LSPT and DRT performance via potential CAF over-reliance, with the opposite occurring following negative perceptions. The benefits associated with CAF expectancies may better suit tasks that entail lesser cognitive-/skill-specific attributes but greater gross motor function and this is likely due to reduced RPE. In isolation, these effects appear greater vs. CAF pharmacology. However, an additive benefit may be observed after combining expectancy with CAF pharmacology (i.e., synergism).N/

Genetic Influences on Cattle Grazing Distribution: Association of Genetic Markers with Terrain Use in Cattle

Eighty-seven cows were GPS (Global Positioning System) tracked for 1 to 3 months in mountainous and/or extensive pastures at five ranches located in New Mexico, Arizona, and Montana. The Illumina Bovine HD SNP array, which evaluates approximately 770,000 genetic markers (i.e., single nucleotide polymorphisms; SNPs) across the 30 bovine chromosomes, was used to genotype DNA from these cows and to examine genetic associations with grazing distribution. Terrain use indexes were calculated from tracking data based on normalized averages of slope use, elevation use, and distance travelled from water. Genetic analyses identified a chromosomal region, known as a quantitative trait locus (QTL), associated with these traits. One genetic marker on chromosome 29 identified a gene that has been reported to be involved in locomotion, motivation, and spatial memory. This locus accounted for 24% of the phenotypic variation in use of steep slopes and high elevations, while another QTL on chromosome 17 accounted for 23% of the phenotypic variation. Three other QTLs accounted for 10% to 20% of the variation in terrain use indexes. Using results from the initial high-density genetic marker analyses, a smaller 50-SNP panel was developed targeting previously identified QTL regions and was used to evaluate the 85 cows tracked previously with an additional 73 cows from four ranches. With the 50-SNP panel analyses, multiple genetic markers near or within the gene identified on chromosome 29 confirmed the association with indexes of terrain use. In addition, genetic markers on chromosomes 4, 8, 12, and 17 accounted for a significant portion of the phenotypic variation in terrain use indexes. The associations between terrain use indexes and genetic markers near candidate genes demonstrate that grazing distribution can be inherited and provide a new approach to associate genetic variation with cattle grazing behavior of range beef cattle. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information