Intensity of Treadmill Training and its Effect on Body Composition in Rats

Abstract

The purpose of this study was to determine which of three intensities of treadmill training produced changes in body composition in rats as evidenced by body weight, percentage of fat and specific gravity. Subjects were 60 male Wistar rats 25 to 30 days old when obtained. They were randomly assigned to one of five groups: sedentary controls, spontaneously active controls, and three groups of rats forced to exercise on a treadmill at intensities of 75, 125 and 175 fpm. Forced exercise was applied three times a week for 8 weeks, after which measures of body weight, specific gravity, and percentage of body fat were obtained. Results indicated that the sedentary controls had significantly higher mean body weights than did those which exercised. Rats forced to exercise at 75 fpm had significantly lower specific gravity measures than rats trained at 125 fpm. Sedentary controls had lower specific gravity values than did all rats allowed to exercise. Intensity of treadmill training had no effect on percentage of body fat as determined chemically. However, exercise was effective in reduction of body fat.     

Effect of postural changes on 3D joint angular velocity during starting block phase

Abstract

Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis® system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments.     

Muscle Fiber Type Composition and Knee Extension Isometric Strength Fatigue Patterns in Power- and Endurance-Trained Males

Abstract

Muscle fiber type composition in the vastus lateralis and knee extension isometric strength fatigue patterns were assessed in eight endurance-trained and eight power-trained males. Two different 25-trial isometric contraction exercise regimens were administered: a 10-second contraction, 5-second intertrial rest condition designed to induce a fast rate of fatigue and a 10-second contraction, 20-second intertrial rest condition designed to induce a slower rate of fatigue. The power group fatigued almost four times faster than the endurance group in the 10:5 exercise condition. In the 10:20 exercise condition, the endurance group showed no fatigue pattern while the power group had a significant strength decrement of 32%. In both exercise conditions, the power group exhibited more complex fatigue patterns in terms of statistically significant trend components. Maximum isometric strength correlated positively with slow twitch (ST) percent number in power (r = .80) and endurance (r = .48) groups, but negatively with linear trend coefficients in endurance (r = -.62) and power (r = -.80) groups. Maximum isometric strength also correlated higher with fatigue curve trend coefficients than did muscle fiber type composition. Thus, a faster rate of fatigue was associated with higher maximum isometric strength and with higher ST percent number and area. Since maximum isometric strength correlated with body weight (r = .86 for groups combined), both maximum isometric strength and muscle mass appear to be more important determinants of knee extension isometric strength fatigue patterns than muscle fiber type composition.     

Observing Coaches’ Leadership Behaviours: the Development of the Coach Leadership Assessment System (CLAS)

ABSTRACT

The purpose of the present study was to develop an observational coding system that examines coaches’ leadership behaviours in sport. Drawing from an integration of the dimensions emphasized within the full-range leadership model, and particularly, transformational leadership (TFL), the Coach Leadership Assessment System (CLAS) was designed to examine coaches’ real-time leadership behaviours. Behavioural categories were developed through an iterative combination of literature review, qualitative interviews, and video observation. The CLAS consists of five higher-order dimensions: transformational, transactional, neutral, laissez-faire, and toxic coaching, which assess coaches’ leadership across 18 distinct behavioural categories. Overall, results provided preliminary support for the reliability and validity of this instrument. The CLAS provides a detailed and contextualized account of coaches’ leadership behaviours in sport and may have important implications for theory development and applied practice.     

THE DIFFERENCES IN SCORES AND SELF-EFFICACY BY STUDENT GENDER IN MATHEMATICS AND SCIENCE

Typically, mathematics and science are seen as linked together, where both subjects involve numbers, critical thinking, and problem solving. Our study aims to develop a better understanding of the connections between student’s achievement scores in mathematics and science, student gender, and self-efficacy. We used the Trends in International Mathematics and Science Study 2007 eighth grade data to answer our research questions and were able to demonstrate that when controlling for self-efficacy, there is a statistically significant difference in the achievement scores between males and females by subject, where females score higher Algebra, but males score higher in the other mathematics subjects. Likewise, we were also able to demonstrate that there is a statistically significant difference in the achievement scores in Earth Science, Physics, and Biology, between males and females where males score higher in science subjects. In both mathematics and science examinations, we controlled for self-efficacy where in mathematics females hold lower self-efficacy then males and in science there is no difference between females and males in terms of self-efficacy. We conjecture that mathematics and science classrooms that consider self-efficacy may impact student’s achievement scores by subject, which can ultimately impact career choices in mathematics- and science-based fields.     

Developing Mobile Based Instruction

This paper describes an instructional design class??s experience developing instruction for the mobile web. The class was taught at a southeastern university in the United States in a master??s level computer based instruction course. Two example projects are showcased and student reflections on design issues are highlighted. Additionally, challenges and lessons learned from this experience are described. This case study will benefit those who are considering teaching a course on designing mobile learning; also to those who are considering developing mobile instructional websites.