Caffeine supplementation does not affect match activities and fatigue resistance during match play in young football players

Abstract

The study examined the effect of caffeine supplementation on match activities and development of fatigue during a football match. In a randomised, double-blind cross-over design, two experimental football games separated by 7 days were organised between the junior teams of two professional football clubs (17.6 ± 1.1 years (±s), 71.7 ± 6.9 kg, 13.9% ± 5.0% body fat). The players ingested either a capsule of 6 mg · kg^?1 b.w. caffeine or placebo (dextrose) 65 min prior to the matches. Match activities were assessed using the ZXY match analysis system, and a Yo-Yo intermittent recovery test–level 2 (Yo-Yo IR2) was conducted immediately post-game. Heart rate was monitored throughout the game, and blood samples were obtained at baseline, half-time and after the game. There were no differences between caffeine and placebo regarding total distance covered (10,062 ± 916 vs 9854 ± 901 m), high-intensity running (557 ± 178 vs 642 ± 240 m), sprinting distance (109 ± 58 vs 112 ± 69 m) or acceleration counts (123 ± 31 vs 126 ± 24). In both trials, players displayed lower (P < 0.05) values in total distance and acceleration counts in the last 15 min compared to all other 15-min periods of the matches. Post-game Yo-Yo IR2 performance was not different between game trials (caffeine: 829 ± 322 m; placebo 819 ± 289 m). In conclusion, oral caffeine administration does not appear to have an ergogenic effect in young football players during match play.     

Future pest status of an insect pest in museums,Attagenus smirnovi: Distribution and food consumption in relation to climate change

The brown carpet beetle Attagenus smirnovi, Zhantiev 1973 (Coleoptera: Dermestidae) is an important pest of objects of organic origin in museums of cultural and natural history in Europe. Future climate changes are expected to lead to increasing temperatures, which will affect the pest status of this species. In the present study a laboratory investigation was conducted to elucidate the effect of temperature and humidity on the amounts of organic material consumed by larvae of A. smirnovi. In the case of new and old skin, consumption was approximately twice as high at 28 °C compared to 20 °C. Wool was consumed in the greatest amounts: 169 mg of wool was consumed in three months by 30 A. smirnovi larvae. The expected future climate changes in Scandinavia are assumed to lead to higher temperatures in museums and stores where climate is not regulated. Updated data on the present distribution of A. smirnovi in Europe show that it is widespread and common, also in regions with a climate that does not support its survival out of doors. Thus, dispersal of this pest probably only rarely occurs by flight, but usually with human activity. Due to the widespread distribution of A. smirnovi, it is likely that damages in museums and collections in Scandinavia due to this pest will increase as climate changes come into effect.     

A Review of the Physics and the Building Science which Underpins Methods of Low Energy Storage of Museum and Archive Collections*

ABSTRACT

The need to keep things cool for durability should be the single most powerful influence on storage design. The simplest temperature control is to moderate the outside temperature by a combination of thermal insulation and heat capacity. The low energy storage building is a lightweight, thermally insulated, airtight building put on top of an uninsulated floor slab laid directly on the ground. The thermal insulation is calculated to even out the daily temperature cycle but to allow an annual temperature cycle which is about half the amplitude, but much smoother, than the annual temperature cycle outside. The winter temperature inside will nearly always be above ambient and so will maintain a moderate RH without need for either humidification or dehumidification. The temperature inside in summer will be below ambient and thus will force dehumidification of the infiltrating air. However, the airtightness of the building allows intermittent dehumidification with low energy consumption, less than one kWh/m³ per year. There now exist enough buildings designed on this principle to reassure curators that highly valued collections can be stored in a space with a gentle temperature cycle and with an RH stability as good as air-conditioning usually achieves.     

Breakdowns in collaborative information seeking: A study of the medication process

Collaborative information seeking is integral to many professional activities. In hospital work, the medication process encompasses continual seeking for information and collaborative grounding of information. This study investigates breakdowns in collaborative information seeking through analyses of the use of the electronic medication record adopted in a Danish healthcare region and of the reports of 5 years of medication incidents at Danish hospitals. The results show that breakdowns in collaborative information seeking is a major source of medication incidents, that most of these breakdowns are breakdowns in collaborative grounding rather than information seeking, that the medication incidents mainly concern breakdowns in the use of records as opposed to oral communication, that the breakdowns span multiple degrees of separation between clinicians, and that the electronic medication record has introduced risks of new kinds of breakdown in collaborative information seeking. In working to prevent and recover from breakdowns in the seeking and sharing of information a focus on collaborative information seeking will point toward collaborative, organizational, and systemic reasons for breakdown and areas for improvement, rather than toward individual error.     

Innovation: Exploring the knowledge base

New types of knowledge, and new ways of organising the production of it, may emerge as knowledge producers respond to the challenges posed by a changing society. This paper focuses on the core knowledge of one such emerging field, namely, innovation studies. To explore the knowledge base of the field, a database of references in scholarly surveys of various aspects of innovation, published in “handbooks”, is assembled and a new methodology for analysing the knowledge base of a field with the help of such data is developed. The paper identifies the core contributions to the literature in this area, the most central scholars and important research environments, and analyses - with the help of citations in scholarly journals - how the core literature is used by researchers in different scientific disciplines and cross-disciplinary fields. Based on this information a cluster analysis is used to draw inferences about the structure of the knowledge base on innovation. Finally, the changing character of the field over time is analysed, and possible challenges for its continuing development are discussed.     

Traditional balance and slackline training are associated with task-specific adaptations as assessed with sensorimotor tests

The purpose of this study was to measure alterations in sensorimotor skills and balance resulting from slackline training and conventional balance training. Forty-three physically fit subjects were randomized into three groups. Two groups practiced three times a week for 15?minutes, including at least once supervised session, on the slackline or perform conventional balance training for 6 weeks. The control group was not allowed to perform any balance training. Before and after the intervention, the subjects underwent sensorimotor and strength tests. The results of our intra-class correlation analysis showed that the stability parameters from the multifunctional training device (MFT, 0.7), the height during the countermovement jump (CMJ, 0.95) and the maximum force (0.88) during leg press showed excellent reliability. A post hoc comparison indicated a larger effect of conventional training (almost 11% reduction in MFT stability) compared with slackline training in group-wide comparisons of the pre- to the post-training measurements. The factor analysis showed that stability and sensorimotor assessment using MFT were correlated, as were height during CMJ and maximal force during leg press, which represented dynamic strength. Because CMJ had the highest intra-class correlation value, it was chosen over maximum force from leg press. For these reasons, only two out of nine measured parameters, namely MFT stability and CMJ, were analysed across groups. The only observed difference between the two groups was MFT stability (slackline???1.5%, conventional???13%), whereas the improvement of CMJ was the same (slackline?+?3%, conventional?+?3%). It can be concluded that slacklining is partly complementary to conventional sensorimotor training.