Sex and Athletic Status as Factors in Reaction Latency and Movement Time

Abstract

This study investigated the effects of sex and athletic status on reaction latencies and movement time. One hundred subjects, categorized into five groups of 20 subjects each—male athletes (MA), female athletes (FA), male nonathletes (MNA), female nonathletes (FNA), and control group (CG)—were tested over a period of five consecutive days. Several different types of incentives were used to ensure that subjects provided the fastest times possible. Two blocks of 25 trials were administered to each subject on each day. A 2 × 2 × 2 × 5 × 2 mixed factorial analysis of variance was used to test for between-subject differences of group (experimental/control), sex, and athletic status and for within-subject differences of days and blocks. The four dependent variables were reaction time (RT) mean, RT consistency, movement time (MT) mean, and MT consistency. Results did not support the classic finding of male superiority over females in RT/MT or athletes' superiority over nonathletes. Evidence of athletic superiority emerged, but for the first day of practice only. As subjects were allowed extended practice over a 5-day test period in which knowledge of results (KR) and other incentives were provided, differences in the experimental groups disappeared. Sex was the predominant factor in consistency, with males being less variable in RT (p = .02) performance than females. There were no sex differences in MT consistency.     

Children and Fitness: A Public Health Perspective: A Response

Abstract

The speed-accuracy operating curve was investigated in a movement precuing two- or four-choice reaction time task. Four levels of response preferences were manipulated with subject instructions and postresponse information: (a) accuracy, (b) reaction time latency, (c) accuracy and reaction time latency, and (d) no preference. Eighty subjects completed 480 discrete keypressing responses with the index and middle fingers of both hands. The mixed design mean reaction time analysis indicated faster performances for the reaction time latency and the accuracy and reaction time latency groups than the no preference group. Additionally, the percent correct analysis revealed two significant interactions: (a) Trial Block x Precue x Response Preference, and (b) Delay x Precue x Hand Position. Overall, the present findings provide partial support for the speed-accuracy operating curve predictions. Caution is advised when drawing chronometric inferences based only on reaction time data or when response accuracies are extremely high.     

Premotor and Motor Reaction Time As a Function of Response Complexity

Abstract

Two experiments were conducted to identify the response elements responsible for the complexity effect found by Henry and Rogers (1960). An attempt was made to determine if these elements were affecting the premotor time component of simple reaction time (SRT). If they were, a strong case could be made for the argument that neuromotor programming time was affected because premotor time is a more exact estimate of it than SRT. The results revealed that premotor time was unaffected by a forward change in movement direction, but increased as the number of movement parts increased from one to two and as the demand for movement accuracy increased. Thus, increasing the (1) number of parts and (2) accuracy demands were identified as elements of response complexity which increase programming time and support Henry and Rogers (1960) hypothesis that the time to initiate a response becomes longer as the programming process become more complex.     

Fractionated Reaction Time Responses to Auditory and Electrocutaneous Stimuli

Abstract

It is well documented that simple reaction time (RT) varies inversely with stimulus intensity, but there is disagreement as to which stimulus modality produces the fastest simple RT. An investigation was conducted to equate two stimulus modalities, auditory (A) and electrocutaneous (EC), using varying stimulus intensities in a simple RT protocol. A second investigation was then conducted to examine neuromotor characteristics of stimulus-evoked responses using previously equated A and EC stimuli of varying intensity from the first investigation. Results showed that RT, premotor time (PMT), and motor time (MT) were all inversely related to stimulus intensity, while maximum displacement (MAXD) was directly related to stimulus intensity, and movement time was not affected by stimulus intensity. We conclude that: (a) both central and peripheral components of RT are altered by varying stimulus intensities, and (b) rapid movements are enhanced by increasing stimulus intensity.     

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

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.     

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

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.     

中国羽毛球队让球事件的连锁反应——竞技体育参与者利益分化的突显

伦敦奥运会中国、韩国、印尼羽毛球运动员因消极比赛被国际羽联取消本届奥运会参赛资格,韩国对消极比赛的运动员、教练员给予重罚,而国羽＂让球主角＂被奖、庆功宴对＂让球事件＂闭口不提。同样的消极比赛不同的处理方式显示两国历史文化及国情的差异。羽毛球队让球事件的连锁反应是竞技体育参与者利益分化的凸显,因此建立竞技体育利益制衡机制,是实现竞技体育利益平衡的关键。     

Hammer acceleration due to thrower and hammer movement patterns

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.     

浅谈氧化还原反应方程式的配平

介绍用化合价升降法配平无机、有机氧化还原反应方程式。     

二溴羟基偶氮胂褪色光度法测定微量铈

在硫酸介质中,Ce(Ⅳ)对二溴羟基偶氮胂有强烈的氧化褪色作用,由此建立了分光光度法测定铈的新方法.实验表明,在室温条件下,加入各种试剂混匀后,有色溶液快速褪色,ΔA值达到最大,有色溶液的最大吸收波长为530nm,方法的线性范围为0～8 5μg/mL,线性回归方程为:ΔA=0 1646CCe(μg/mL)-0 0194,检出限为1 66×10-6μg/mL.该方法用于人发样中的微量铈的测定,结果满意.