Notices     

Adrian Lees  Tudor Hale  J. G. P. Williams  ED Winter  Ian M. Cockerill 《Journal of sports sciences》2013,31(1):69-70

Kinanthropometry III. Proceedings of the VIII Commonwealth and International Conference on Sport, Physical Education, Dance, Recreation and Health. T. Reilly, J. Watkins and J. Borms (eds), E. &; F.N. Spon, London, 1986, xii + 312 pp, £25 (hb), ISBN 0 419 13970 2

Sensible fitness. J.H. Wilmore, Human Kinetics, Champaign, Illinois, USA, 1986, xii + 300 pp, $11.95, ISBN 0 88011 270 0

Running without fear. K.H. Cooper, Bantam Books, London, 1985, 256 pp, £3.95, ISBN 0 553 17356 1

Athletic training and sports medicine. American Academy of Orthopaedic Surgeons, Churchill Livingstone, Chicago, USA, 1986. viii + 602 pp, £40, ISBN 0 89203 002 X

Athletics and the heart. R. Rost, Year Book Medical Publishers Inc., Chicago, 1987, vii+159 pp, £21.50 (pb), ISBN 0 8151 7397 0

Psychology and sociology of sport: current selected research, Volume 1. L.V. Velden and J.M. Humprey (eds), AMS Press, New York, 1986, ix + 237 pp, £49.50 (hb), ISBN 0 404 63401 X  相似文献   

Fatigue decreases skilled tennis performance     

Polly R. Davey  Rod D. Thorpe  Clyde Williams 《Journal of sports sciences》2013,31(4):311-318

The aim of this study was to examine the effect of fatigue from maximal tennis hitting on skilled tennis performance. Eighteen senior county tennis players (9 males, 9 females) volunteered to participate in the study. Their mean ( - s x -macron ) age and body mass were as follows: males 20.7 - 0.9 years and 60.6 - 2.7 kg respectively, females 21.7 - 0.6 years and 71.5 - 1.8 kg respectively. The players undertook two performance tests, both against a tennis ball serving machine, on an indoor tennis surface: (1) a pre- and post-skill test of groundstrokes and service; (2) the Loughborough Intermittent Tennis Test (4 min work plus 40 s recovery) to volitional fatigue. Body mass decreased by 1.5% ( P ? 0.0001). Mean heart rates differed between rest, post-warm-up and all intermittent test values ( P ? 0.01), between the pre- and post-skill tests ( P ? 0.0001) and between bouts and recoveries ( P ? 0.01). Peak blood glucose and lactate concentrations were 5.9 mmol· l -1 (50% into the intermittent tennis test) and 9.6 - 0.9 mmol· l -1 (25% into the test) respectively. Mean time to volitional fatigue was 35.4 - 4.6 min. Groundstroke hitting accuracy decreased by 69% from start to volitional fatigue in the intermittent test ( P ? 0.01). Service accuracy to the right court declined by 30% after the intermittent tennis test. The results of this study suggest that fatigue was accompanied by a decline in some but not all tennis skills.  相似文献   

BASES Annual Conference, 4–7 September 2005, Loughborough University,UK     

Clyde Williams 《Journal of sports sciences》2013,31(11-12):1147-1148

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An analysis of practice activities and instructional behaviours used by youth soccer coaches during practice: Exploring the link between science and application     

Paul R. Ford  Ian Yates  A. Mark Williams 《Journal of sports sciences》2013,31(5):483-495

Abstract

We examined the practice activities and instructional behaviours employed by 25 youth soccer coaches during 70 different practice sessions. We evaluated the extent to which these activities and behaviours differ from those shown in contemporary research to best facilitate skill acquisition. Nine coaches worked with the under-9 years age group and eight coaches each with the under-13 and under-16 years age groups; nine of those coaches were employed at the elite level, nine at the sub-elite level, and seven at the non-elite level. Coaches had players spend more time in activities that were deemed less relevant to soccer match performance, termed “training form” (e.g. physical training, technique and skills practices), than activities deemed more relevant, termed “playing form” (e.g. small-sided/conditioned games and phase of play activities). Coaches provided high levels of instruction, feedback, and management, irrespective of the activity in which players engaged. Few differences in practice activities and instructional behaviours were reported across skill and age groups, implying the absence of any notable age- or skill-related progression. Findings are discussed with reference to recent research in the areas of skill acquisition, motor learning, and expert performance.  相似文献   

Influence of ingesting a carbohydrate-electrolyte solution before and during a 1-hour run in fed endurance-trained runners     

Ian Rollo  Clyde Williams 《Journal of sports sciences》2013,31(6):593-601

Abstract

The aim of this study was to determine whether the ingestion of a carbohydrate-electrolyte solution would improve 1-h running performance in runners who had consumed a meal 3 h before exercise. Ten endurance-trained male runners completed two trials that required them to run as far as possible in 1 h on an automated treadmill that allowed changes in running speed without manual input. Following the consumption of the pre-exercise meal, which provided 2.5 g carbohydrate per kilogram body mass (BM), runners ingested either a 6.4% carbohydrate-electrolyte solution or placebo solution (i.e. 8 ml · kg BM^?1) 30 min before and 2 ml · kg BM^?1 at 15-min intervals throughout the 1-h run. There were no differences in total distance covered (placebo: 13,680 m, s = 1525; carbohydrate: 13,589 m, s = 1635) (P > 0.05). Blood glucose and lactate concentration, respiratory exchange ratio, and carbohydrate oxidation during exercise were not different between trials (P > 0.05). There were also no differences in ratings of perceived exertion, felt arousal or pleasure–displeasure between trials (P > 0.05). In conclusion, the ingestion of a 6.4% carbohydrate-electrolyte solution did not improve 1-h running performance when a high carbohydrate meal was consumed 3 h before exercise.  相似文献   

Genetics of muscle strength and power: Polygenic profile similarity limits skeletal muscle performance     

David C. Hughes  Stephen H. Day  Ildus I. Ahmetov  Alun G. Williams 《Journal of sports sciences》2013,31(13):1425-1434

Abstract

Environmental and genetic factors influence muscle function, resulting in large variations in phenotype between individuals. Multiple genetic variants (polygenic in nature) are thought to influence exercise-related phenotypes, yet how the relevant polymorphisms combine to influence muscular strength in individuals and populations is unclear. In this analysis, 22 genetic polymorphisms were identified in the literature that have been associated with muscular strength and power phenotypes. Using typical genotype frequencies, the probability of any given individual possessing an “optimal” polygenic profile was calculated as 0.0003% for the world population. Future identification of additional polymorphisms associated with muscular strength phenotypes would most likely reduce that probability even further. To examine the genetic potential for muscular strength within a human population, a “total genotype score” was generated for each individual within a hypothetical population of one million. The population expressed high similarity in polygenic profile with no individual differing by more than seven genotypes from a typical profile. Therefore, skeletal muscle strength potential within humans appears to be limited by polygenic profile similarity. Future research should aim to replicate more genotype–phenotype associations for muscular strength, because only five common genetic polymorphisms identified to date have positive replicated findings.  相似文献   

Nutritional practices associated with low energy availability in Division I female soccer players     

Jennifer L. Reed  Mary Jane De Souza  Joseph M. Kindler  Nancy I. Williams 《Journal of sports sciences》2013,31(16):1499-1509

Abstract

The purpose of this study was to examine macronutrient intake, energy density and energy intake distribution that may be associated with low energy availability (EA) in Division I female soccer players. The energy intake, exercise energy expenditure and EA of 19 participants (18–21 years) was assessed during the pre-, mid- and postseasons. Repeated measures analysis of variance was performed to examine the changes across the season. Chi-square analysis was performed to examine the distribution of participants meeting the American College of Sports Medicine recommendations for carbohydrate and protein consumption. Independent t-tests were used to compare differences between groups. The proportion of athletes who did not meet the American College of Sports Medicine recommendations for carbohydrate intake (6–10 g . kg^–1 BW) was significantly greater in the low (<30 kcal . kg^–1 LBM) than higher (≥30 kcal . kg^–1 LBM) EA group (χ² (1) = 7.5; P = 0.006). Participants with low compared to higher EA consumed a lower energy dense dinner (0.8 ± 0.1 vs. 1.4 ± 0.1 kcal . g^–1; P = 0.004) after a soccer match during midseason. No differences in the percentage (%) of kilocalories from food (84.5 ± 2.0% vs. 84.7 ± 2.6%), sports drinks (7.3 ± 1.4% vs. 6.0 ± 3.2%), other drinks (7.6 ± 1.5 % vs. 6.0 ± 1.5%) or bars/gels/beans (1.7 ± 0.6 vs. 3.0 ± 1.5) were observed in participants with low compared to higher EA (P > 0.05) during the pre- and midseasons. Identifying inadequate carbohydrate intake and the practice of consuming lower energy dense meals may be important in preventing low EA conditions and consequently the Female Athlete Triad.  相似文献   

Can we trust “Magnitude-based inference”?     

Alan M. Nevill  A. Mark Williams  Colin Boreham  Eric S. Wallace  Gareth W. Davison  Grant Abt 《Journal of sports sciences》2013,31(24):2769-2770

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Comparison of Female Athlete Triad Coalition and RED-S risk assessment tools     

Kristen J. Koltun  Nicole C. A. Strock  Emily A. Southmayd  Andrew P. Oneglia  Nancy I. Williams  Mary Jane De Souza 《Journal of sports sciences》2013,31(21):2433-2442

ABSTRACT

The Female Athlete Triad Coalition (Triad Coalition) and Relative Energy Deficiency in Sport (RED-S) consensus statements each include risk assessment tools to guide athlete eligibility decisions. This study examined how these tools categorized the same set of individuals to an overall risk factor score and qualitatively compared athlete eligibility decisions resulting from each tool. Exercising women (n = 166) with complete screening/baseline datasets from multiple previously conducted studies were assessed. Data used for risk assessment included: anthropometric measurements, dual-energy x-ray absorptiometry scans, exercise and health status surveys, and two disordered eating questionnaires (Three Factor Eating Questionnaire and Eating Disorder Inventory). Individuals were scored on each tool and subsequently categorized as either fully cleared, provisionally cleared, or restricted from play. Based on the Triad Coalition tool, 25.3% of subjects were classified as fully cleared, 62.0% as provisionally cleared, and 12.7% as restricted from play. Based on the RED-S tool, 71.7% of subjects were classified as fully cleared, 18.7% as provisionally cleared, and 9.6% as restricted from play. The Triad Coalition and RED-S tools resulted in different clearance decisions (p < 0.001), with the Triad Coalition tool recommending increased surveillance of a greater number of athletes.  相似文献   

Effect of water ingestion on endurance capacity during prolonged running     

Joanne L. Fallowfield  Clyde Williams  Jeanette Booth  Boon H. Choo  Sally Growns 《Journal of sports sciences》2013,31(6):497-502

This study examined the influence of water ingestion on endurance capacity during submaximal treadmill running. Four men and four women with a mean (± S.E.) age of 21.4 ± 0.7 years, height of 169 + 2 cm, body mass of 63.1 ± 2.9 kg and VO ₂ max of 51.1 ± 1.8 ml kg^?1 min^?1, performed two randomly assigned treadmill runs at 70% VO ₂ max to exhaustion. No fluid was ingested during one trial (NF‐trial), whereas a single water bolus of 3.0 ml kg^?1 body mass was ingested immediately pre‐exercise and serial feedings of 2.0 ml kg^?1 body mass were ingested every 15 min during exercise in a fluid replacement trial (FR‐trial). Run time for the NF‐trial was 77.7 ± 7.7 min, compared to 103 ± 12.4 min for the FR‐trial (P<0.01). Body mass (corrected for water ingestion) decreased by 2.0 ± 0.2% in the NF‐trial and 2.7 ± 0.2% in the FR‐trial (P<0.01), while plasma volume decreased by 1.1 ± 1.1% and 3.5 ± 1.1% in the two trials respectively (N.S.). However, these apparent differences in circulatory volume were not associated with differences in rectal temperature. Respiratory exchange ratios indicated increased carbohydrate metabolism (73% vs 64% of total energy expenditure) and suppressed fat metabolism after 75 min of exercise in the NF‐trial compared with the FR‐trial (NF‐trial, 0.90 ± 0.01; FR‐trial, 0.86 ± 0.03; P<0.01). Blood glucose concentrations were similar in both trials, while blood lactate concentrations were higher in the NF‐trial at the end of exercise (4.83 ± 0.34 vs 4.18 ± 0.38 mM; P<0.05). In summary, water ingestion during prolonged running improved endurance capacity.  相似文献