Dietary supplements for football

Physical training and competition in football markedly increase the need for macro- and micronutrient intake. This requirement can generally be met by dietary management without the need for dietary supplements. In fact, the efficacy of most supplements available on the market is unproven. In addition, players must be cautious of inadequate product labelling and supplement impurities that may cause a positive drug test. Nonetheless, a number of dietary supplements may beneficially affect football performance. A high endurance capacity is a prerequisite for optimal match performance, particularly if extra time is played. In this context, the potential of low-dose caffeine ingestion (2 - 5 mg . kg body mass(-1)) to enhance endurance performance is well established. However, in the case of football, care must be taken not to overdose because visual information processing might be impaired. Scoring and preventing goals as a rule requires production of high power output. Dietary creatine supplementation (loading dose: 15 - 20 g . day(-1), 4 - 5 days; maintenance dose: 2 - 5 g g . day(-1)) has been found to increase muscle power output, especially during intermittent sprint exercises. Furthermore, creatine intake can augment muscle adaptations to resistance training. Team success and performance also depend on player availability, and thus injury prevention and health maintenance. Glucosamine or chondroitin may be useful in the treatment of joint pain and osteoarthritis, but there is no evidence to support the view that the administration of these supplements will be preventative. Ephedra-containing weight-loss cocktails should certainly be avoided due to reported adverse health effects and positive doping outcomes. Finally, the efficacy of antioxidant or vitamin C intake in excess of the normal recommended dietary dose is equivocal. Responses to dietary supplements can vary substantially between individuals, and therefore the ingestion of any supplement must be assessed in training before being used in competition. It is recommended that dietary supplements are only used based on the advice of a qualified sports nutrition professional.     

Contamination of dietary supplements and positive drug tests in sport

The use of dietary supplements is widespread in sport and most athletes competing at the highest level of competition use some form of dietary supplementation. Many of these supplements confer no performance or health benefit, and some may actually be detrimental to both performance and health when taken in high doses for prolonged periods. Some supplements contain excessive doses of potentially toxic ingredients, while others do not contain significant amounts of the ingredients listed on the label. There is also now evidence that some of the apparently legitimate dietary supplements on sale contain ingredients that are not declared on the label but that are prohibited by the doping regulations of the International Olympic Committee and of the World Anti-Doping Agency. Contaminants that have been identified include a variety of anabolic androgenic steroids (including testosterone and nandrolone as well as the pro-hormones of these compounds), ephedrine and caffeine. This contamination may in most cases be the result of poor manufacturing practice, but there is some evidence of deliberate adulteration of products. The principle of strict liability that applies in sport means that innocent ingestion of prohibited substances is not an acceptable excuse, and athletes testing positive are liable to penalties. Although it is undoubtedly the case that some athletes are guilty of deliberate cheating, some positive tests are likely to be the result of inadvertent ingestion of prohibited substances present in otherwise innocuous dietary supplements.     

Dietary supplements for athletes: emerging trends and recurring themes

Dietary supplements are widely used at all levels of sport. Changes in patterns of supplement use are taking place against a background of changes in the regulatory framework that governs the manufacture and distribution of supplements in the major markets. Market regulation is complicated by the increasing popularity of Internet sales. The need for quality control of products to ensure they contain the listed ingredients in the stated amount and to ensure the absence of potentially harmful substances is recognized. This latter category includes compounds prohibited under anti-doping regulations. Several certification programmes now provide testing facilities for manufacturers of both raw ingredients and end products to ensure the absence of prohibited substances. Athletes should carry out a cost-benefit analysis for any supplement they propose to use. For most supplements, the evidence is weak, or even completely absent. A few supplements, including caffeine, creatine, and bicarbonate, are supported by a strong research base. Difficulties arise when new evidence appears to support novel supplements: in recent years, β-alanine has become popular, and the use of nitrate and arginine is growing. Athletes seldom wait until there is convincing evidence of efficacy or of safety, but caution is necessary to minimize risk.     

Measuring physical activity in preschoolers: Reliability and validity of The System for Observing Fitness Instruction Time for Preschoolers (SOFIT-P)

The purpose of this study is describe the initial feasibility, reliability, and validity of an instrument to measure physical activity in preschoolers using direct observation. The System for Observing Fitness Instruction Time for Preschoolers was developed and tested among 3- to 6-year-old children over fall 2008 for feasibility and reliability (Phase I, n=67) and in fall 2009 for concurrent validity (Phase II, n=27). Phase I showed that preschoolers spent >75% of their active time at preschool in light physical activity. The mean inter-observer agreements scores were ≥.75 for physical activity level and type. Correlation coefficients, measuring construct validity between the lesson context and physical activity types with and with the activity levels, were moderately strong. Phase II showed moderately strong correlations ranging from .50 to .54 between the System for Observing Fitness Instruction Time for Preschoolers and Actigraph accelerometers for physical activity levels. The System for Observing Fitness Instruction Time for Preschoolers shows promising initial results as a new method for measuring physical activity among preschoolers.     

运动时心脏猝死的预防

近年来,剧烈运动如马拉松赛跑和足球运动致心脏猝死报告增多。因此,研究运动时心脏猝死的预防很有必要。一、赛前普查:未经过训练的人突然参加不习惯的运动时易诱发心脏病。故在从事新运动前应对他们进行普查。这将有助于发现致命性的心血管病,但对     

Parental socialization, vagal regulation, and preschoolers' anxious difficulties: direct mothers and moderated fathers

Parental supportiveness and protective overcontrol and preschoolers' parasympathetic regulation were examined as predictors of temperamental inhibition, social wariness, and internalizing problems. Lower baseline vagal tone and weaker vagal suppression were expected to mark poorer dispositional self-regulatory capacity, leaving children more susceptible to the influence of parental socialization. Less supportive mothers had preschoolers with more internalizing problems. One interaction between baseline vagal tone and maternal protective overcontrol, predicting social wariness, conformed to the moderation hypothesis. Conversely, vagal suppression moderated several links between paternal socialization and children's anxious difficulties in the expected pattern. There were more links between mothers' self-reported parenting and child outcomes than were noted for direct observations of maternal behavior, whereas the opposite tended to be true for fathers.     

Writing-to-learn in undergraduate science education: a community-based, conceptually driven approach

Despite substantial evidence that writing can be an effective tool to promote student learning and engagement, writing-to-learn (WTL) practices are still not widely implemented in science, technology, engineering, and mathematics (STEM) disciplines, particularly at research universities. Two major deterrents to progress are the lack of a community of science faculty committed to undertaking and applying the necessary pedagogical research, and the absence of a conceptual framework to systematically guide study designs and integrate findings. To address these issues, we undertook an initiative, supported by the National Science Foundation and sponsored by the Reinvention Center, to build a community of WTL/STEM educators who would undertake a heuristic review of the literature and formulate a conceptual framework. In addition to generating a searchable database of empirically validated and promising WTL practices, our work lays the foundation for multi-university empirical studies of the effectiveness of WTL practices in advancing student learning and engagement.     

Sleep and adjustment in preschool children: sleep diary reports by mothers relate to behavior reports by teachers

Prior literature suggests that there may be relations between children's sleep disorders or inadequate amounts of sleep and behavioral adjustment. Most relevant studies concern clinical populations, however, and relatively few concern community populations. Moreover, previous studies have not addressed empirically the possible role of family functioning as a factor in the relation between children's sleep and adjustment. The present study, conducted in a predominantly low-income, community sample (N = 202), measured 4- to 5-year-old children's sleep patterns through daily logs kept by mothers, and measured family stress and parenting practices through detailed, multifaceted interviews and incidental observations of parent-child interactions. Children's adjustment, both positive and negative, was measured through preschool teacher reports on multiple occasions. A structural equation model showed that disrupted child sleep patterns (variability in reported amount of sleep, variability in bedtime, and lateness of bedtime) predicted less optimal adjustment in preschool, even after considering the roles of family stress and family management practices.