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PURPOSE OF THE STATEMENT: ▸ To provide an evidence-based, best practises summary to assist physicians with the evaluation and management of sports concussion. ▸ To establish the level of evidence, knowledge gaps and areas requiring additional research. IMPORTANCE OF AN AMSSM STATEMENT: ▸ Sports medicine physicians are frequently involved in the care of patients with sports concussion. ▸ Sports medicine physicians are specifically trained to provide care along the continuum of sports concussion from the acute injury to return-to-play (RTP) decisions. ▸ The care of athletes with sports concussion is ideally performed by healthcare professionals with specific training and experience in the assessment and management of concussion. Competence should be determined by training and experience, not dictated by specialty. ▸ While this statement is directed towards sports medicine physicians, it may also assist other physicians and healthcare professionals in the care of patients with sports concussion. DEFINITION: ▸ Concussion is defined as a traumatically induced transient disturbance of brain function and involves a complex pathophysiological process. Concussion is a subset of mild traumatic brain injury (MTBI) which is generally self-limited and at the less-severe end of the brain injury spectrum. PATHOPHYSIOLOGY: ▸ Animal and human studies support the concept of postconcussive vulnerability, showing that a second blow before the brain has recovered results in worsening metabolic changes within the cell. ▸ Experimental evidence suggests the concussed brain is less responsive to usual neural activation and when premature cognitive or physical activity occurs before complete recovery the brain may be vulnerable to prolonged dysfunction. INCIDENCE: ▸ It is estimated that as many as 3.8 million concussions occur in the USA per year during competitive sports and recreational activities; however, as many as 50% of the concussions may go unreported. ▸ Concussions occur in all sports with the highest incidence in football, hockey, rugby, soccer and basketball. RISK FACTORS FOR SPORT-RELATED CONCUSSION: ▸ A history of concussion is associated with a higher risk of sustaining another concussion. ▸ A greater number, severity and duration of symptoms after a concussion are predictors of a prolonged recovery. ▸ In sports with similar playing rules, the reported incidence of concussion is higher in female athletes than in male athletes. ▸ Certain sports, positions and individual playing styles have a greater risk of concussion. ▸ Youth athletes may have a more prolonged recovery and are more susceptible to a concussion accompanied by a catastrophic injury. ▸ Preinjury mood disorders, learning disorders, attention-deficit disorders (ADD/ADHD) and migraine headaches complicate diagnosis and management of a concussion. DIAGNOSIS OF CONCUSSION: ▸ Concussion remains a clinical diagnosis ideally made by a healthcare provider familiar with the athlete and knowledgeable in the recognition and evaluation of concussion. ▸ Graded symptom checklists provide an objective tool for assessing a variety of symptoms related to concussions, while also tracking the severity of those symptoms over serial evaluations. ▸ Standardised assessment tools provide a helpful structure for the evaluation of concussion, although limited validation of these assessment tools is available. SIDELINE EVALUATION AND MANAGEMENT: ▸ Any athlete suspected of having a concussion should be stopped from playing and assessed by a licenced healthcare provider trained in the evaluation and management of concussions. ▸ Recognition and initial assessment of a concussion should be guided by a symptoms checklist, cognitive evaluation (including orientation, past and immediate memory, new learning and concentration), balance tests and further neurological physical examination. ▸ While standardised sideline tests are a useful framework for examination, the sensitivity, specificity, validity and reliability of these tests among different age groups, cultural groups and settings is largely undefined. Their practical usefulness with or without an individual baseline test is also largely unknown. ▸ Balance disturbance is a specific indicator of a concussion, but not very sensitive. Balance testing on the sideline may be substantially different than baseline tests because of differences in shoe/cleat-type or surface, use of ankle tape or braces, or the presence of other lower extremity injury. ▸ Imaging is reserved for athletes where intracerebral bleeding is suspected. ▸ There is no same day RTP for an athlete diagnosed with a concussion. ▸ Athletes suspected or diagnosed with a concussion should be monitored for deteriorating physical or mental status. NEUROPSYCHOLOGICAL TESTING: ▸ Neuropsychological (NP) tests are an objective measure of brain-behaviour relationships and are more sensitive for subtle cognitive impairment than clinical exam. ▸ Most concussions can be managed appropriately without the use of NP testing. ▸ Computerised neuropsychological (CNP) testing should be interpreted by healthcare professionals trained and familiar with the type of test and the individual test limitations, including a knowledgeable assessment of the reliable change index, baseline variability and false-positive and false-negative rates. ▸ Paper and pencil NP tests can be more comprehensive, test different domains and assess for other conditions which may masquerade as or complicate assessment of concussion. ▸ NP testing should be used only as part of a comprehensive concussion management strategy and should not be used in isolation. ▸ The ideal timing, frequency and type of NP testing have not been determined. ▸ In some cases, properly administered and interpreted NP testing provides an added value to assess cognitive function and recovery in the management of sports concussions. ▸ It is unknown if use of NP testing in the management of sports concussion helps prevent recurrent concussion, catastrophic injury or long-term complications. ▸ Comprehensive NP evaluation is helpful in the post-concussion management of athletes with persistent symptoms or complicated courses. RETURN TO CLASS: ▸ Students will require cognitive rest and may require academic accommodations such as reduced workload and extended time for tests while recovering from a concussion. RETURN TO PLAY: ▸ Concussion symptoms should be resolved before returning to exercise. ▸ A RTP progression involves a gradual, step-wise increase in physical demands, sports-specific activities and the risk for contact. ▸ If symptoms occur with activity, the progression should be halted and restarted at the preceding symptom-free step. ▸ RTP after concussion should occur only with medical clearance from a licenced healthcare provider trained in the evaluation and management of concussions. SHORT-TERM RISKS OF PREMATURE RTP: ▸ The primary concern with early RTP is decreased reaction time leading to an increased risk of a repeat concussion or other injury and prolongation of symptoms. LONG-TERM EFFECTS: ▸ There is an increasing concern that head impact exposure and recurrent concussions contribute to long-term neurological sequelae. ▸ Some studies have suggested an association between prior concussions and chronic cognitive dysfunction. Large-scale epidemiological studies are needed to more clearly define risk factors and causation of any long-term neurological impairment. DISQUALIFICATION FROM SPORT: ▸ There are no evidence-based guidelines for disqualifying/retiring an athlete from a sport after a concussion. Each case should be carefully deliberated and an individualised approach to determining disqualification taken. EDUCATION: ▸ Greater efforts are needed to educate involved parties, including athletes, parents, coaches, officials, school administrators and healthcare providers to improve concussion recognition, management and prevention. ▸ Physicians should be prepared to provide counselling regarding potential long-term consequences of a concussion and recurrent concussions. PREVENTION: ▸ Primary prevention of some injuries may be possible with modification and enforcement of the rules and fair play. ▸ Helmets, both hard (football, lacrosse and hockey) and soft (soccer, rugby) are best suited to prevent impact injuries (fracture, bleeding, laceration, etc.) but have not been shown to reduce the incidence and severity of concussions. ▸ There is no current evidence that mouth guards can reduce the severity of or prevent concussions. ▸ Secondary prevention may be possible by appropriate RTP management. LEGISLATION: ▸ Legislative efforts provide a uniform standard for scholastic and non-scholastic sports organisations regarding concussion safety and management. FUTURE DIRECTIONS: ▸ Additional research is needed to validate current assessment tools, delineate the role of NP testing and improve identification of those at risk of prolonged post-concussive symptoms or other long-term complications. ▸ Evolving technologies for the diagnosis of concussion, such as newer neuroimaging techniques or biological markers, may provide new insights into the evaluation and management of sports concussion.

BACKGROUND: Understanding the risk and trends of sports-related concussion among 12 scholastic sports may contribute to concussion detection, treatment, and prevention. PURPOSE: To examine the incidence and relative risk of concussion in 12 high school boys' and girls' sports between academic years 1997-1998 and 2007-2008. STUDY DESIGN: Descriptive epidemiology study. METHODS: Data were prospectively gathered for 25 schools in a large public high school system. All schools used an electronic medical record-keeping program. A certified athletic trainer was on-site for games and practices and electronically recorded all injuries daily. RESULTS: In sum, 2651 concussions were observed in 10 926 892 athlete-exposures, with an incidence rate of 0.24 per 1000. Boys' sports accounted for 53% of athlete-exposures and 75% of all concussions. Football accounted for more than half of all concussions, and it had the highest incidence rate (0.60). Girls' soccer had the most concussions among the girls' sports and the second-highest incidence rate of all 12 sports (0.35). Concussion rate increased 4.2-fold (95% confidence interval, 3.4-5.2) over the 11 years (15.5% annual increase). In similar boys' and girls' sports (baseball/softball, basketball, and soccer), girls had roughly twice the concussion risk of boys. Concussion rate increased over time in all 12 sports. CONCLUSION: Although the collision sports of football and boys' lacrosse had the highest number of concussions and football the highest concussion rate, concussion occurred in all other sports and was observed in girls' sports at rates similar to or higher than those of boys' sports. The increase over time in all sports may reflect actual increased occurrence or greater coding sensitivity with widely disseminated guidance on concussion detection and treatment. The high-participation collision sports of football and boys' lacrosse warrant continued vigilance, but the findings suggest that focus on concussion detection, treatment, and prevention should not be limited to those sports traditionally associated with concussion risk.

CONTEXT: Sports specialization is intense training in 1 sport while excluding others. Sports specialization in early to middle childhood has become increasingly common. While most experts agree that some degree of sports specialization is necessary to achieve elite levels, there is some debate as to whether such intense practice time must begin during early childhood and to the exclusion of other sports to maximize potential for success. There is a concern that sports specialization before adolescence may be deleterious to a young athlete. EVIDENCE ACQUISITION: PubMed and OVID were searched for English-language articles from 1990 to 2011 discussing sports specialization, expert athletes, or elite versus novice athletes, including original research articles, consensus opinions, and position statements. RESULTS: For most sports, there is no evidence that intense training and specialization before puberty are necessary to achieve elite status. Risks of early sports specialization include higher rates of injury, increased psychological stress, and quitting sports at a young age. Sports specialization occurs along a continuum. Survey tools are being developed to identify where athletes fall along the spectrum of specialization. CONCLUSION: Some degree of sports specialization is necessary to develop elite-level skill development. However, for most sports, such intense training in a single sport to the exclusion of others should be delayed until late adolescence to optimize success while minimizing injury, psychological stress, and burnout.

BACKGROUND: In the United States (US), an estimated 300,000 sports-related concussions occur annually. Among individuals 15 to 24 years of age, sports are second only to motor vehicle crashes as the leading cause of concussions. PURPOSE: To investigate the epidemiology of concussions in high school athletes by comparing rates and patterns of concussion among 20 sports. STUDY DESIGN: Descriptive epidemiology study. METHODS: Using an Internet-based data collection tool, RIO, certified athletic trainers from a large, nationally disperse sample of US high schools reported athlete exposure and injury data for 20 sports during the 2008-2010 academic years. RESULTS: During the study period, 1936 concussions were reported during 7,780,064 athlete-exposures (AEs) for an overall injury rate of 2.5 per 10,000 AEs. The injury rate was higher in competition (6.4) than practice (1.1) (rate ratio [RR], 5.7; 95% confidence interval [CI], 5.2-6.3). The majority of concussions resulted from participation in football (47.1%, n = 912), followed by girls' soccer (8.2%, n = 159), boys' wrestling (5.8%, n = 112), and girls' basketball (5.5%, n = 107). Football had the highest concussion rate (6.4), followed by boys' ice hockey (5.4) and boys' lacrosse (4.0). Concussions represented a greater proportion of total injuries among boys' ice hockey (22.2%) than all other sports studied (13.0%) (injury proportion ratio [IPR], 1.7; 95% CI, 1.4-2.1; P < .01). In gender-comparable sports, girls had a higher concussion rate (1.7) than boys (1.0) (RR, 1.7; 95% CI, 1.4-2.0). The most common mechanisms of injury were player-player contact (70.3%) and player-playing surface contact (17.2%). In more than 40% of athletes in sports other than girls' swimming and girls' track, concussion symptoms resolved in 3 days or less. Athletes most commonly returned to play in 1 to 3 weeks (55.3%), with 22.8% returning in less than 1 week and 2.0% returning in less than 1 day. CONCLUSION: Although interest in sports-related concussions is usually focused on full-contact sports like football and ice hockey, concussions occur across a wide variety of high school sports. Concussion rates vary by sport, gender, and type of exposure. An understanding of concussion rates, patterns of injury, and risk factors can drive targeted preventive measures and help reduce the risk for concussion among high school athletes in all sports.

Brief Contents Preface PART I: Contingency Framework For Strategic Sports Marketing Chapter 1 Emergence of Sports Marketing Chapter 2 Contingency Framework for Strategic Sports Marketing PART II: Planning For Market Selection Decisions Chapter 3 Research Tools for Understanding Sports Consumers Chapter 4 Understanding Participants as Consumers Chapter 5 Understanding Spectators as Consumers Chapter 6 Segmentation, Targeting, and Positioning PART III: Planning The Sports Marketing Mix Chapter 7 Sports Product Concepts Chapter 8 Managing Sports Products Chapter 9 Promotion Concepts Chapter 10 Promotion Mix Elements Chapter 11 Sponsorship Programs Chapter 12 Pricing Concepts and Strategies PART IV: Implementing And Controlling The Strategic Sports Marketing Process Chapter 13 Implementing and Controlling the Strategic Sports Marketing Process Appendix A:Career Opportunities in Sports Marketing Appendix B:Sports Marketing Sites of Interest on the Internet Glossary Photo Credits Index

The aim was to examine the association between this breakpoint (NIRS) and VT2 in welltrained runners.Gas exchange and NIRS data were collected during an incremental VO2max running test for 10 well-trained runners.The breakpoint calculated in oxygen saturation (StO2) and the VT2 were determined and compared in terms relative to %VO2max, absolute speed, VO2 and maximum heart rate (HRmax).There were no significant differences (p>0.05) between the breakpoint in StO2 and VT2 relative to %VO2max (87.00±6.14 and 88.28±3.98 %), absolute speed (15.70±1.42 and 16.10±1.66km•h -1 ), VO2 (53.71±15.17and 54.66±15.57ml•kg -1 •min -1 ) and %HRmax (90.90± 4.17 and 91.84 ± 3.70 %).There were large and significant correlations between instruments relative to %VO2max (r=0.68,p<0.05), absolute speed (r=0.86,p<0.001),VO2 (r=0.86,p<0.001) and %HRmax (r = 0.69; p<0.05).A Bland and Altman analysis of agreement between instruments resulted in a mean difference of -1.27±4.49%,-0.40±0.84km•h -1 , -0.90±3.07ml•kg -1 •min -1 , and -0.94±3.14 for %VO2max, absolute speed, VO2 and %HRmax, respectively.We conclude that a portable NIRS determination of the StO2 breakpoint is comparable with VT2 using gas exchange and therefore appropriate for use in determining exercise training above VT2 intensity.This is the first study to analyze the validity with the running mode using a NIRS portable device.

BACKGROUND: The prevalence of jumper's knee across different sports has not been examined, and it is not known if there is a gender difference. Data from surgical case series indicate that there may be a high prevalence in sports with high speed and power demands. HYPOTHESIS: The aim of this study was to estimate the prevalence of jumper's knee in different sports among female and male athletes and to correlate the prevalence to the loading characteristics of the extensor mechanism in these sports. STUDY DESIGN: Cross-sectional study; Level of evidence, 4. METHODS: The authors examined approximately 50 Norwegian male and female athletes at the national elite level from each of the following 9 sports: athletics (male athletes: high jump, 100- and 200-m sprint), basketball (male athletes), ice hockey (male athletes), volleyball (male athletes), orienteering (male athletes), road cycling (male athletes), soccer (male and female athletes), team handball (male and female athletes), and wrestling (male athletes). The examination included an interview on individual characteristics (weight, age, height, and training background), a clinical examination, and self-recorded Victorian Institute of Sport Assessment score from 0 (worst) to 100 (best). RESULTS: The overall prevalence of current jumper's knee was 14.2% (87 of 613 athletes), with a significant difference between sports with different performance characteristics (range, 0%-45%). In addition, 51 athletes (8%) reported previous symptoms. The prevalence of current symptoms was highest in volleyball (44.6%+/-6.6%) and basketball (31.9%+/-6.8%), whereas there were no cases in cycling or orienteering. The prevalence of current jumper's knee was lower among women (5.6%+/-2.2%) compared with men (13.5%+/-3.0%; chi2 test, P=.042). The duration of symptoms among athletes with current jumper's knee (n=87) was 32+/-25 (standard deviation) months, with a Victorian Institute of Sport Assessment score of 64+/-19. CONCLUSION: The prevalence of jumper's knee is high in sports characterized by high demands on speed and power for the leg extensors. The symptoms are often serious, resulting in long-standing impairment of athletic performance.

PURPOSE: To identify whether parental history of myopia and/or parent-reported children's visual activity levels can predict juvenile-onset myopia. METHODS: Survey-based data from Orinda Longitudinal Study of Myopia subjects from 1989 to 2001 were used to predict future myopia. Univariate and multiple logistic regression analyses were performed, and receiver operator characteristic (ROC) curves were generated. Differences among the areas under the ROC curves were compared using the method of multiple comparison with the best. RESULTS: Of the 514 children eligible for this analysis, 111 (21.6%) became myopic. Differences in the third grade between eventual myopes and nonmyopes were seen for the number of myopic parents (P < 0.001) and for the number of sports and outdoor activity hours per week (11.65 +/- 6.97 hours for nonmyopes vs. 7.98 +/- 6.54 hours for future myopes, P < 0.001). Analysis of the areas under the ROC curves showed three variables with a predictive value better than chance: the number of myopic parents, the number of sports and outdoor activity hours per week, and the number of reading hours per week. After controlling for sports and outdoor hours per week and parental myopia history, reading hours per week was no longer a statistically significant factor. The area under the curve for the parental myopia history and sports and outdoor activities model was 0.73. A significant interaction in the logistic model showed a differential effect of sport and outdoor activity hours per week based on a child's number of myopic parents. CONCLUSIONS: Parental history of myopia was an important predictor in univariate and multivariate models, with a differential effect of sports and outdoor activity hours per week based on the number of myopic parents. Lower amounts of sports and outdoor activity increased the odds of becoming myopic in those children with two myopic parents more than in those children with either zero or one myopic parent. The chance of becoming myopic for children with no myopic parents appears lowest in the children with the highest amount of sports and outdoor activity, compared with those with two myopic parents.

Coaching is a central feature of sport at all levels. This groundbreaking new text is the first to offer a comprehensive introduction to the conceptual issues that underpin sports coaching practice, and to provide a complete conceptual framework for understanding sports coaching. The analysis presented within the book is practice-orientated, exploring the language of the coaching process in order to define the role of the coach, and to better understand the relationship between the coach and the sports performer. Sports Coaching Concepts introduces the key issues behind every stage of the coaching process, presenting important new material on topics such as: * the historical and international context of the development of sports coaching* the role of the coach* participation and performance coaching modes* modelling the coaching process* coaching 'style' and 'philosophy'* decision-making and regulating the process* social factors influencing practice* the future of coach education and professionalisation. The book draws together the existing sports coaching literature for the first time, setting it against important new conceptual developments, and promises to have a profound influence on the nature of our coach education programmes. This book therefore represents essential reading for any student of sports coaching and any serious coach wishing to develop and extend their own coaching practice.

Athletes are among the groups of people who are interested in the effects of caffeine on endurance and exercise capacity. Although many studies have investigated the effect of caffeine ingestion on exercise, not all are suited to draw conclusions regarding caffeine and sports performance. Characteristics of studies that can better explore the issues of athletes include the use of well-trained subjects, conditions that reflect actual practices in sport, and exercise protocols that simulate real-life events. There is a scarcity of field-based studies and investigations involving elite performers. Researchers are encouraged to use statistical analyses that consider the magnitude of changes, and to establish whether these are meaningful to the outcome of sport. The available literature that follows such guidelines suggests that performance benefits can be seen with moderate amounts (~3 mg.kg-1 body mass) of caffeine. Furthermore, these benefits are likely to occur across a range of sports, including endurance events, stop-and-go events (e.g., team and racquet sports), and sports involving sustained high-intensity activity lasting from 1-60 min (e.g., swimming, rowing, and middle and distance running races). The direct effects on single events involving strength and power, such as lifts, throws, and sprints, are unclear. Further studies are needed to better elucidate the range of protocols (timing and amount of doses) that produce benefits and the range of sports to which these may apply. Individual responses, the politics of sport, and the effects of caffeine on other goals, such as sleep, hydration, and refuelling, also need to be considered.

BACKGROUND: Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words 'sport nutrition'. Consequently, staying current with the relevant literature is often difficult. METHODS: This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches. CONCLUSIONS: This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.

BACKGROUND: Current methods for injury registration in sports injury epidemiology studies may substantially underestimate the true burden of overuse injuries due to a reliance on time-loss injury definitions. OBJECTIVE: To develop and validate a new method for the registration of overuse injuries in sports. METHODS: A new method, including a new overuse injury questionnaire, was developed and validated in a 13-week prospective study of injuries among 313 athletes from five different sports, cross-country skiing, floorball, handball, road cycling and volleyball. All athletes completed a questionnaire by email each week to register problems in the knee, lower back and shoulder. Standard injury registration methods were also used to record all time-loss injuries that occurred during the study period. RESULTS: The new method recorded 419 overuse problems in the knee, lower back and shoulder during the 3-month-study period. Of these, 142 were classified as substantial overuse problems, defined as those leading to moderate or severe reductions in sports performance or participation, or time loss. Each week, an average of 39% of athletes reported having overuse problems and 13% reported having substantial problems. In contrast, standard methods of injury registration registered only 40 overuse injuries located in the same anatomical areas, the majority of which were of minimal or mild severity. CONCLUSION: Standard injury surveillance methods only capture a small percentage of the overuse problems affecting the athletes, largely because few problems led to time loss from training or competition. The new method captured a more complete and nuanced picture of the burden of overuse injuries in this cohort.

Since the 1950s, taxpayers have been the primary investors in stadia built for the use of privately-owned professional sports teams. Team owners have argued that sports facilities boost local economic activity; however, economic reasoning and empirical evidence suggest the opposite. Public support for stadia is also driven by demand for community image, and owners of sports teams supply a scarce input into image enhancement--participation in the major league--for which they have been able to extract monopoly rents from dispersed taxpayers. We suggest reforms to dissipate the monopoly sports leagues exercise when negotiating with host communities for their teams.

OBJECTIVE: To encourage increased participation in physical activity among Americans of all ages by issuing a public health recommendation on the types and amounts of physical activity needed for health promotion and disease prevention. PARTICIPANTS: A planning committee of five scientists was established by the Centers for Disease Control and Prevention and the American College of Sports Medicine to organize a workshop. This committee selected 15 other workshop discussants on the basis of their research expertise in issues related to the health implications of physical activity. Several relevant professional or scientific organizations and federal agencies also were represented. EVIDENCE: The panel of experts reviewed the pertinent physiological, epidemiologic, and clinical evidence, including primary research articles and recent review articles. CONSENSUS PROCESS: Major issues related to physical activity and health were outlined, and selected members of the expert panel drafted sections of the paper from this outline. A draft manuscript was prepared by the planning committee and circulated to the full panel in advance of the 2-day workshop. During the workshop, each section of the manuscript was reviewed by the expert panel. Primary attention was given to achieving group consensus concerning the recommended types and amounts of physical activity. A concise "public health message" was developed to express the recommendations of the panel. During the ensuing months, the consensus statement was further reviewed and revised and was formally endorsed by both the Centers for Disease Control and Prevention and the American College of Sports Medicine. CONCLUSION: Every US adult should accumulate 30 minutes or more of moderate-intensity physical activity on most, preferably all, days of the week.

We discuss current knowledge on the description, impact, and underlying causes of circadian rhythmicity in sports performance. We argue that there is a wealth of information from both applied and experimental work, which, when considered together, suggests that sports performance is affected by time of day in normal entrained conditions and that the variation has at least some input from endogenous mechanisms. Nevertheless, precise information on the relative importance of endogenous and exogenous factors is lacking. No single study can answer both the applied and basic research questions that are relevant to this topic, but an appropriate mixture of real-world research on rhythm disturbances and tightly controlled experiments involving forced desynchronization protocols is needed. Important issues, which should be considered by any chronobiologist interested in sports and exercise, include how representative the study sample and the selected performance tests are, test-retest reliability, as well as overall design of the experiment.

Statistical guidelines and expert statements are now available to assist in the analysis and reporting of studies in some biomedical disciplines. We present here a more progressive resource for sample-based studies, meta-analyses, and case studies in sports medicine and exercise science. We offer forthright advice on the following controversial or novel issues: using precision of estimation for inferences about population effects in preference to null-hypothesis testing, which is inadequate for assessing clinical or practical importance; justifying sample size via acceptable precision or confidence for clinical decisions rather than via adequate power for statistical significance; showing SD rather than SEM, to better communicate the magnitude of differences in means and nonuniformity of error; avoiding purely nonparametric analyses, which cannot provide inferences about magnitude and are unnecessary; using regression statistics in validity studies, in preference to the impractical and biased limits of agreement; making greater use of qualitative methods to enrich sample-based quantitative projects; and seeking ethics approval for public access to the depersonalized raw data of a study, to address the need for more scrutiny of research and better meta-analyses. Advice on less contentious issues includes the following: using covariates in linear models to adjust for confounders, to account for individual differences, and to identify potential mechanisms of an effect; using log transformation to deal with nonuniformity of effects and error; identifying and deleting outliers; presenting descriptive, effect, and inferential statistics in appropriate formats; and contending with bias arising from problems with sampling, assignment, blinding, measurement error, and researchers' prejudices. This article should advance the field by stimulating debate, promoting innovative approaches, and serving as a useful checklist for authors, reviewers, and editors.

Contents: Preface. K.A. Ericsson, The Acquisition of Expert Performance: An Introduction to Some of the Issues. N. Charness, R. Krampe, U. Mayr, The Role of Practice and Coaching in Entrepreneurial Skill Domains: An International Comparison of Life-Span Chess Skill Acquisition. J.L. Starkes, J.M. Deakin, F. Allard, N.J. Hodges, A. Hayes, Deliberate Practice in Sports: What Is It Anyway? J.A. Sloboda, The Acquisition of Musical Performance Expertise: Deconstructing the Account of Individual Differences in Musical Expressivity. V.L. Patel, D.R. Kaufman, S.A. Magder, The Acquisition of Medical Expertise in Complex Dynamic Environments. H.B. Richman, F. Gobet, J.J. Staszewski, H.A. Simon, Perceptual and Memory Processes in the Acquisition of Expert Performance: The EPAM Model. R.K. Wagner, K.E. Stanovich, Expertise in Reading. D.K. Simonton, Creative Expertise: A Life-Span Developmental Perspective. M.J.A. Howe, The Childhoods and Early Lives of Geniuses: Combining Psychological and Biographical Evidence. E. Winner, The Rage to Master: The Decisive Role of Talent in the Visual Arts. R. Glaser, Changing the Agency for Learning: Acquiring Expert Performance. F.L. Holmes, Expert Performance and the History of Science. J.B. Shea, G. Paull, Capturing Expertise in Sports. R.M. Shiffrin, Laboratory Experimentation on the Genesis of Expertise. R.J. Sternberg, Costs of Expertise.

In this article, I have attempted to apply my cognitive-motivational-relational theory of emotion, on which I have been working for over 50 years, to an understanding of performance in competitive sports. I begin with four metatheoretical and theoretical positions: (a) stress and emotion should be considered as a single topic; (b) discrete emotion categories offer the richest and most useful information; (c) appraisal, coping, and relational meaning are essential theoretical constructs for stress and emotion; and (d) although process and structure are both essential to understanding, when it comes to stress and the emotions, we cannot afford to under-emphasize process. These positions and elaborations of them lead to my examination of how a number of discrete emotions might influence performance in competitive sports.

Recognized both nationally and internationally as the leading reference guide in the field, this volume provides a scientific basis for analyzing the various sports techniques used in baseball, basketball, football, golf, gymnastics, softball, swimming, and track and field's running, jumping, and throwing. KEY TOPICS: The book explains how these techniques are used by first considering the basic factors involved in the performance of each technique, then discusses the current controversies and latest research findings surrounding each technique ... includes revised coverage of track and field -- the sport in which the most important research advances have been made ... discusses basic biomechanical concepts in order, from simple to complex, with each new concept building upon the last ... covers often overlooked aspects such as impulse, mechanical energy, lift and drag, and the segmentation method of locating the center of gravity of an athlete ... provides coverage of forms of motion, linear and angular kinematics, linear and angular kinetics, and fluid mechanics ... plus, contains new and revised illustrations throughout. Ideal for sports trainers, therapists, and anyone involved in biomechanics.