Cardiopulmonary loading in motocross riding     

Tomi Konttinen  Keijo Häkkinen 《Journal of sports sciences》2013,31(9):995-999

Abstract

The present study was designed to examine physiological responses during motocross riding. Nine Finnish A-level motocross riders performed a 15-min ride at a motocross track and a test of maximal oxygen uptake ([Vdot]O_2max) in the laboratory. Cardiopulmonary strain was measured continuously during the ride as well as in the [Vdot]O_2max test. During the ride, mean [Vdot]O₂ was 32 ml · kg^?1 · min^?1 (s = 4), which was 71% (s = 12) of maximum, while ventilation (V _E) was 73% (s = 15) of its maximum. The relative [Vdot]O₂ and V _E values during the riding correlated with successful riding performance (r = 0.80, P < 0.01 and r = 0.79, P < 0.01, respectively). Mean heart rate was maintained at 95% (s = 7) of its maximum. Mean blood lactate concentration was 5.0 mmol · l^?1 (s = 2.0) after the ride. A reduction of 16% (P < 0.001) in maximal isometric handgrip force was observed. In conclusion, motocross causes riders great physical stress. Both aerobic and anaerobic metabolism is required for the isometric and dynamic muscle actions experienced during a ride.  相似文献   

Mechanics of Batting: Effect of Stride Technique on Ground Reaction Forces and Bat Velocities     

Stephen P. Messier  Marjorie G. Owen 《Research quarterly for exercise and sport》2013,84(4):329-333

The benefits associated with being physically active are well documented, but a significant proportion of the population is insufficiently active. Physical inactivity is a major health risk factor in our society, and physical education programs are consistently identified as a means to address this concern. The purpose of this article is to use the social-ecological model as a framework to examine ways in which physical education programs can play an important role in promoting physical activity. Policies that require time allocations and resources for physical education and physical activity in schools and community designs that provide infrastructure that makes being physically active accessible and convenient are important factors in making schools and communities healthier spaces. It is clear, however, that policies alone are not sufficient to address concerns about physical inactivity. We must consider individual factors that influence decisions to be physically active in efforts to engage children in physical education programs that promote active lifestyles. The learning climate that teachers create determines what students do and learn in physical education classes. Ensuring that students see value in the content presented and structuring classes so that students believe they can experience success when they exert effort are key elements in an effective motivational climate. Efforts to address public health concerns about physical inactivity require a comprehensive approach including quality physical education. It is critical that kinesiology professionals emerge as leaders in these efforts to place physical education programs at the center of promoting children's physical activity.  相似文献   

The Kinematics and Kinetics of the Running Pattern of Two-, Four-, and Six-Year-Old Children     

Virginia L. Fortney 《Research quarterly for exercise and sport》2013,84(2):126-135

Abstract

Selected kinematic and kinetic variables in the running pattern of 2-, 4-, and 6-year-old children were investigated. Cinematographic records and force-plate tracings were used to study the running patterns of the 28 Caucasian subjects, 15 male and 13 female. A 2 × 3 (sex × age) factorial analysis of variance was used to determine whether effects of variation between and within age and sex factors for each of the dependent variables of selected kinematic (displacement and velocity) and kinetic (ground reaction force) variables were significant. The running speeds improved with age. Although height and weight gains influenced the improvement shown in performance, certain biomechanical variables also contributed to the development of the running pattern. In the majority of the selected kinematic and kinetic variables there were significant differences between the 2-year-old group and the other two groups. Where there were significant differences in the variables, the differences tended to be in displacement, velocity, and magnitude of force measures, rather than in time of occurrence measures. Significant differences between male and female subjects appeared in five kinematic variables related to the swing leg.  相似文献   

我国公共体育场地的现状研究     

方曙光 《湖北体育科技》2013,32(4):283-286

运用文献资料、数理统计、专家访谈和逻辑分析等研究方法,根据第五次全国体育场地普查数据资料,从场地类型、分布状况、隶属关系、经济成分、投资方式、场地使用率等方面对我国公共体育场地的现状进行分析。  相似文献   

Hammer acceleration due to thrower and hammer movement patterns     

Koji Murofushi  Shinji Sakurai  Koji Umegaki  Junji Takamatsu 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):301-314

Ground reaction force and wire tensile force were measured during test throws by three hammer throwers: the Asian record holder, who had a personal best of 83.47 m at the time of the investigation, and two university athletes, with personal bests of 59.95 m and 46.30 m respectively. They were filmed using three high-speed video cameras (250 Hz). The displacements of the hammer head and the athletes' centres of mass were calculated using three-dimensional analysis procedures. The Asian record holder's centre of mass and the hammer head on the final two turns exhibited approximate conjunctions of the hammer high point and the thrower's low point and vice versa about the hammer's azimuth angle. It is conjectured that the reason why the thrower's movement is asynchronous with the hammer's movement by approximately half a turn is to accelerate the hammer head in a manner similar to the way that the amplitude of a pendulum increases when it is pulled upward by a string against the downward movement of the swinging weight.  相似文献   

地源热泵在顺德地区应用的可行性分析     

余华明 《顺德职业技术学院学报》2006,4(1):13-15

根据顺德地区自然气候环境、土壤温度状况,对多种不同的热泵系统的节能、技术性和经济性参数进行了比较和分析,证明地源热泵具有节能、环保的优点,在顺德地区具有广阔的发展前景.  相似文献   

学校体育场馆（地）向社会开放的SWOT分析与对策研究     

梁丹  董华 《宁德师专学报(自然科学版)》2012,24(1):40-42

通过对学校体育场馆（地）向社会开放的SWOT（优势、劣势、机遇、威胁）分析,提出了严格规范管理制度、加强安全防护、积极开拓经济来源、处理好教学和开放的关系、政府主导、学校与社区共同参与的对策.  相似文献   

《山石满足了》的认知文体分析     

王铁梅 《鸡西大学学报》2012,12(7):97-98

认知文体学是认知语言学发展的一个新分支。它关注语言形式与其产生的效果之间的关联,分析作者创作与读者阐释的认知机制。认知文体学研究理论框架很多,在此试图从图形背景理论的角度对TedHughes的《山石满足了》(Hill-stone was content)做认知文体学分析,从短语、词汇和语法三个不同层面探讨了图形背景理论的运行机制及其在诗歌意境形成中的作用,同时也分析了此语篇中图形背景互换为表达主题所起的作用,从而为作品的解读提出新的视角。  相似文献   

土壤源热泵在扬州某五星级酒店中的设计探讨     

朱志军  常澄 《泰州职业技术学院学报》2012,12(6):92-94

文章针对节能减排的当前形势,通过对在扬州某建筑中的土壤源热泵经济性及节能性进行的分析,提出了地源热泵使用的可行性。  相似文献   

UCF Library Express: Planning a Faculty Delivery Service     

Karli R. Mair  Kristine J. Shrauger 《Journal of Interlibrary Loan, Document Delivery & Electronic Reserve》2013,23(1-2):5-22

As it becomes increasingly difficult to demonstrate the worth of the library to the academic community, gate counts and usage statistics are no longer enough. Showing the impact the library has on the community requires planning new services with outcome measurement from the start. This article outlines a project plan for launching a faculty book delivery service at the University of Central Florida's John C. Hitt Library using Rhea Rubin's (2006) Outcome Measurement model. The article reviews the relevant literature, analyzes the current internal and external climate in which the service will be implemented, discusses the logistical aspects of the service such as cost, delivery method, and staffing, and concludes by determining the goals and outcomes of the service based on these factors. This article is the first in a series of three articles that together make up an entire project planning and management document, including planning, marketing, and assessing the service. The plan in its entirety provides an example of how to apply the Outcome Measurement model in an academic library setting.  相似文献