A link between diurnal preference and a variable number tandem-repeat (VNTR) polymorphism in the PERIOD3 gene (PER3) has been demonstrated: the longer PER35 and shorter PER34 alleles with preferences for mornings and evenings, respectively. As many competitive events in South Africa for individual athletes are scheduled for the early mornings, we hypothesized that this might favor those athletes with a preference for morning activities. Self-selected white, male cyclists (CYC, n = 125), runners (RUN, n = 120) and Ironman triathletes (IM, n = 287) of European descent were compared with a control population of active, non-competitive individuals (CON, n = 96). The chronotypes of all CYC, RUN and CON participants and a sub-sample of the IM group (n = 49) were assessed using the Horne–Östberg Morningness–Eveningness Questionnaire, and the PER3 VNTR genotype for each participant was determined. The athlete groups contained more morning-type individuals than the CON group (CYC: 72%, n = 90; RUN: 67%, n = 80; IM: 59%, n = 29; CON: 41%, n = 39; p < .001). The prevalence of the PER35 allele was greater in the athlete groups (CYC: 61%, n = 152; RUN: 58%, n = 132; IM: 56%, n = 324; CON: 38%, n = 76; p < .001), and more athletes were genotyped as PER35/5 than CON individuals (CYC: 41%, n = 51; RUN: 23%, n = 26; IM: 28%, n = 81, CON: 9%, n = 8; p < .001). A strong relationship between chronotype and PER3 VNTR genotype was observed (p < .001). Finally, the time of day at which the athletes preferred to train was related to their chronotype (p < .001). This is the first study of its kind in a South African sporting population, and the results have not yet been replicated. These data suggest that white males of European descent participating in individual endurance sports in South Africa are more likely to be morning types. Furthermore, the PER3 VNTR may be one of the factors contributing to this observation. (Author correspondence: laura.roden@uct.ac.za) 相似文献
In all member countries of the European Community, the influence of European directives is increasing. This is especially the case with directives on the conservation of natural habitats and wild fauna and flora (European Council Directive 92/43 EEC from 1992 (Council of the European Union 1992) and the directive on the conservation of wild birds (European Council directive 79/409 EEC from 1979 (Council of the European Union 1979). These directives are expected to influence the future development of nature-based sport and outdoor recreation significantly. Many German sport organisations are expecting negative consequences for the future development of nature-based sport in mountain areas. This paper summarises key findings of a study commissioned by the German Sport Association.
This project develops guidelines for the application and interpretation of these directives, as well as for their practicable use and management. The study shows that the potential negative effects of nature-based sport and outdoor recreation activities can be categorised into three general types. Furthermore, large sport events should be evaluated separately in the future. Finally, the crucial role of management plans is discussed, which are essential if NATURA 2000 areas are to be established successfully. The management plan assists in the selection of suitable measures, helps to resolve conflicts, and increases the level of acceptance and its transparency for the public. This paper will demonstrate that the consultation and participation of local people including members of sport and recreational organisations is essential to achieve the best result in the interest of nature conservation in general and conservation of endangered habitats or species specifically. 相似文献
The purpose of this study was to examine the effects of creatine supplementation on the incidence of injury observed during 3-years of NCAA Division IA college football training and competition. In an open label manner, athletes participating in the 1998–2000 football seasons elected to take creatine or non-creatine containing supplements following workouts/practices. Subjects who decided to take creatine were administered 15.75 g of creatine for 5 days followed by ingesting an average of 5 g/day thereafter administered in 5–10 g doses. Creatine intake was monitored and recorded by research assistants throughout the study and ranged between 34–56% of players during the course of the study. Subjects practiced or played in environmental conditions ranging from 8–40°C (mean 24.7 ± 9°C) and 19–98% relative humidity (49.3 ± 17%). Injuries treated by the athletic training staff were recorded and categorized as cramping, heat/dehydration, muscle tightness, muscle strains/pulls, non-contact joint injuries, contact injuries, and illness. The number of missed practices due to injury/illness was also recorded. Data are presented as the total number of treated injuries for creatine users/total injuries observed and percentage occurrence rate of injuries for creatine users for all seasons. The incidence of cramping (37/96, 39%), heat/dehydration (8/28, 36%), muscle tightness (18/42, 43%), muscle pulls/strains (25/51, 49%), non-contact joint injuries (44/132, 33%), contact injuries (39/104, 44%), illness (12/27, 44%), number of missed practices due to injury (19/41, 46%), players lost for the season (3/8, 38%), and total injuries/missed practices (205/529, 39%) were generally lower or proportional to the creatine use rate among players. Creatine supplementation does not appear to increase the incidence of injury or cramping in Division IA college football players. 相似文献
Creatine has become a popular nutritional supplement among athletes. Recent research has also suggested that there may be a number of potential therapeutic uses of creatine. This paper reviews the available research that has examined the potential ergogenic value of creatine supplementation on exercise performance and training adaptations. Review of the literature indicates that over 500 research studies have evaluated the effects of creatine supplementation on muscle physiology and/or exercise capacity in healthy, trained, and various diseased populations. Short-term creatine supplementation (e.g. 20 g/day for 5–7 days) has typically been reported to increase total creatine content by 10–30% and phosphocreatine stores by 10–40%. Of the approximately 300 studies that have evaluated the potential ergogenic value of creatine supplementation, about 70% of these studies report statistically significant results while remaining studies generally report non-significant gains in performance. No study reports a statistically significant ergolytic effect. For example, short-term creatine supplementation has been reported to improve maximal power/strength (5–15%), work performed during sets of maximal effort muscle contractions (5–15%), single-effort sprint performance (1–5%), and work performed during repetitive sprint performance (5–15%). Moreover, creatine supplementation during training has been reported to promote significantly greater gains in strength, fat free mass, and performance primarily of high intensity exercise tasks. Although not all studies report significant results, the preponderance of scientific evidence indicates that creatine supplementation appears to be a generally effective nutritional ergogenic aid for a variety of exercise tasks in a number of athletic and clinical populations. 相似文献
The purpose of this paper is to elucidate how racism manifests ‘behind closed doors’ in the backstage private domain. We do this with reference to recent high-profile controversies in the US and UK. In particular, we use the concepts of frontstage (public) and backstage (private) racism to unpack the extraordinary case in point of the ex-National Basketball Association franchise owner Donald Sterling. The paper concludes that though it is important for frontstage racism to be disrupted, activist scholars must be mindful of the lesser-known, and lesser-researched, clandestine backstage racism that, we argue, galvanizes more public manifestations. The Donald Sterling case is an example of how backstage racism functions and, potentially, how it can be resisted. 相似文献
Doping is now a global problem that follows international sporting events
worldwide. International sports federations, led by the International Olympic
Committee, have for the past half century attempted to stop the spread of
this problem, with little effect. It was expected that, with educational programs,
testing, and supportive medical treatment, this substance-abusing behavior
would decrease. Unfortunately, this has not been the case. In fact, new, more
powerful and undetectable doping techniques and substances are now abused
by professional athletes, while sophisticated networks of distribution have
developed. Professional athletes are often the role models of adolescent and
young adult populations, who often mimic their behaviors, including the abuse
of drugs. This review of doping within international sports is to inform the
international psychiatric community and addiction treatment professionals
of the historical basis of doping in sport and its spread to vulnerable athletic
and non-athletic populations. 相似文献
The sex ratio of leopards, Panthera pardus, taken by trophyhunters in Tanzania is examined. We used sex specific molecularmarkers to analyze 77 samples collected from animals shot betweenthe years 1995–1998 and found that 28.6% were females, despitethe fact that only males are allowed on licenses and all skinswere tagged as males. The model used for quota setting assumesthat only males are shot, but the effect of this violation ofquotas is unknown. Off-take in Tanzania does not currently fillquotas, but when off-take approach maximum levels, compliancewith set quotas and regulations will be critical for sustainableharvest. 相似文献
ABSTRACT Imitation plays a crucial role in apprenticeship in the Afro-Brazilian performance genre capoeira, as in many skills across cultures. In this article, I examine the interactional dynamics of imitative pedagogy in capoeira to better understand physical education as a form of bodily enculturation. The ability to learn through imitation is widely considered a hallmark of our species. Imitative ability, however, is a social accomplishment rather than a capacity of the learner in isolation. Human models often provide assistance to novices seeking to imitate, including a variety of forms of what educational theorists call "scaffolding," which are astutely structured to a novice's ability, perceptions, and even neurology. Scaffolding techniques vary. I here examine how instructors reduce students' degrees of movement freedom, reorient their model in perceptual space, and parse complex sequences into component gestures. Close analysis of pedagogical interaction highlights the divergence between forms of instruction and practical skills being taught. 相似文献