Technique and timing in women's and men's reverse one and one half somersault with two and one half twists (5335D) and men's reverse one and one half somersault with three and one half twists (5337D) 3 m springboard dives     

Sanders R  Burnett A 《Sports biomechanics / International Society of Biomechanics in Sports》2004,3(1):29-41

The purpose of this study was to compare timing and technique of males and females performing reverse twisting dives in elite international competition. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including takeoff and entry. Estimates of flight height and mass-normalised work done on the springboard were obtained from flight times. The data indicated that many males are able to complete an additional twist rotation because they attain more height, and therefore more time in the air, than females.  相似文献   

The effect of cycling on muscle activation in the running leg of an Olympic distance triathlon     

Heiden T  Burnett A 《Sports biomechanics / International Society of Biomechanics in Sports》2003,2(1):35-49

The aim of this study was to determine the effect of prior cycling on EMG activity of selected lower leg muscles during running. Ten elite level triathletes underwent two testing sessions at race pace: a 40 km cycle followed by a 2 km run (CR) and a 10 km run followed by a 2 km run (RR). EMG data from selected lower limb muscles were collected at three sections of each run (0 km, 1 km and 2 km) for six strides using a portable data logger. Significant differences (p < 0.05) between condition were found for the level of activation (Lact) for biceps femoris (BF) during stance and vastus lateralis (VL) during flight and stance. Vastus medialis (VM) changed in Lact, during flight, between sections in the 2 km run. Furthermore, significant differences (p < 0.05) between condition were found for BF during stance and for rectus femoris (RF) and VM during flight. There was a significant difference (p < 0.05) in the duration of VL activation (Dact) across sections of the 2 km run. Findings from this investigation highlight changes in muscle function when changing from cycling to running and indicate a need to train specifically for the cycle to run transition. Such training may improve performance and reduce the risk of injury.  相似文献   

Raising Activity Levels: A Multidimensional Analysis of Curriculum Change     

David P. Johns  Amy S. C. Ha  Duncan J. Macfarlane 《Sport, Education and Society》2013,18(2):199-210

Using Fullan's (1982) The Meaning of Educational Change (Toronto, OISE Press) multidimensional framework, this paper discusses the problems of curriculum change by examining the subjective experiences of physical education teachers. The discussion was based on interviews with teachers who were involved in a study to change health behaviors of high school students. Although no discernable changes in behavior were observed, the explanations for the results, as reported by the teachers, have provided insights of greater importance. Two physical education classes consisting of boys and girls aged between 11 and 13 years from 20 secondary schools were selected for pre-test and post-test measurements. The data collected included a survey, direct observation, heart rate monitoring and motion sensoring. A teacher-designed modification of the physical education curriculum was used as an intervention as it was specifically aimed at increasing activity. A debriefing of teachers in the experimental group indicated that they considered the teacher-designed lesson guide to be valuable. However, when the teachers were faced with implementing change in their physical classes, they (like the researchers) underestimated the situational and personal-social factors that prevented untested ideas from being transformed into firm beliefs and values. The findings confirmed the predictions of a multidimensional model of educational change, which indicated that, when challenged, technological and material innovations are more easily changed than attitudes, beliefs and values held by teachers.  相似文献   

The effect of coaching intervention on elite fast bowling technique over a two year period     

Craig Ranson  Mark King  Angus Burnett  Peter Worthington  Kevin Shine 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):261-274

Fast bowling in cricket is an activity that is well recognised as having high injury prevalence and there has been debate regarding the most effective fast bowling technique. The aim of this study was to determine whether two-year coaching interventions conducted in a group of elite young fast bowlers resulted in fast bowling technique alteration. Selected kinematics of the bowling action of 14 elite young fast bowlers were measured using an 18 camera Vicon Motion Analysis system before and after two-year coaching interventions that addressed specific elements of fast bowling technique. Mann-Whitney tests were used to determine whether any changes in kinematic variables occurred pre- and post-intervention between those who had the coaching interventions and those who didn't. The coaching interventions, when applied, resulted in a more side-on shoulder alignment at back foot contact (BFC) (p = 0.002) and decreased shoulder counter-rotation (p = 0.001) however, there was no difference in the degree of change in back and front knee flexion angles or lower trunk side-flexion. This study has clearly shown that specific aspects of fast bowling technique are changeable over a two-year period in elite level fast bowlers and this may be attributed to coaching intervention.  相似文献   

The relationship between bowling action classification and three-dimensional lower trunk motion in fast bowlers in cricket     

Craig A. Ranson  Angus F. Burnett  Mark King  Nitin Patel  Peter B. O'Sullivan 《Journal of sports sciences》2013,31(3):267-276

Abstract

Lower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aims of this study were to quantify the proportion of lower trunk motion used during the delivery stride of fast bowling and to examine the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. A high percentage of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30°. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (129%), and ipsilateral rotation (79%) was used during the front foot contact phase of the fast bowling delivery stride. There was no significant difference in the proportions of available lower trunk extension, contralateral side-flexion, and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. Motion of the lower trunk, particularly side-flexion, during front foot contact, in addition to variables previously known to be related to back injury (e.g. shoulder counter-rotation), should be examined in future cross-sectional and prospective studies examining the fast bowling action and low back injury.  相似文献   

The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction     

Angus M. Hunter  Giuseppe De Vito  Claire Bolger  Hugh Mullany  Stuart D. R. Galloway 《Journal of sports sciences》2013,31(12):1261-1269

Abstract

The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; [Vdot]O_2max 62 ml · kg^?1 · min^?1, s = 8) ingested capsules containing either CaCO₃ (placebo) or NaHCO₃ (0.3 g · kg^?1 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO₃ were higher (P < 0.01) during the NaHCO₃ trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO₃ than with placebo (5.1 m · s^?1, s = 0.4 vs. 4.2 m · s^?1, s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling.  相似文献   

Reliability of a combined biomechanical and surface electromyographical analysis system during dynamic barbell squat exercise     

Raphael Brandon  Glyn Howatson  Angus Hunter 《Journal of sports sciences》2013,31(13):1389-1397

Abstract

An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39–0.0057 × knee angle (degress), with goodness-of-fit value, r ² = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods.  相似文献   

A study of user's acceptance on situational mashups in situational language teaching     

Angus F. M. Huang  Stephen J. H. Yang  Shu‐Sheng Liaw 《British journal of educational technology : journal of the Council for Educational Technology》2012,43(1):52-61

Situational awareness and mashups are two key factors influencing the success of situational language teaching. However, traditional situational language teaching cannot smoothly conduct relevant learning activities in changing learning context. This study developed a situational mashups system for detecting users' context and proposed a research model for evaluating users' acceptance on the situational mashups in situational language teaching. The proposed model consisted of users' individual experiences, situational learning theory and technology acceptance theory. The experimental results showed that users' experiences of using computer, Internet, mashups system and mashups‐based learning, as well as users' perceived enjoyment, perceived usefulness and perceived ease of use of situational mashups are all key factors affecting users' acceptance of situational mashups in situational language teaching.  相似文献   

Simulations: Time to take another look!     

Angus Reynolds  Cheryl Samuels-Campbell 《Performance Improvement》1985,24(4):15-17

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