Neuromuscular variables affecting the magnitude of force loss after eccentric exercise

The aim of this study was to examine neuromuscular variables contributing to differences in force loss after participants were exposed to the same relative bout of eccentric exercise. Thirty-six males performed 50 maximal eccentric contractions of the elbow flexors and were stratified into high responders (n = 10) and low responders (n = 10) based on force loss 36 h after exercise. Maximal voluntary isometric contractions (MVCs) and electromyography (EMG) were measured at baseline and 36 h after exercise. During eccentric exercise, mean peak torque, mean end-range torque from the final 25% of each trial and total angular impulse were computed over 25 contractions in each of two bouts. The slope of the change in these values for each 25 eccentric contractions was calculated for each participant using linear regression. At baseline, MVC was not different between groups (low responders: 97.0 +/- 9.6 N x m; high responders: 82.7 +/- 6.4 N x m; P = 0.08). High responders demonstrated a 68% (range 62-78%) reduction in MVC and low responders a 39% (29-48%) reduction after exercise. Peak torque, end-range torque and total angular impulse were 13%, 40% and 33% higher, respectively, in the low than in the high responders (peak torque: P = 0.0002; end-range torque: P < 0.0001; total angular impulse: P < 0.001). The rate of decline in peak torque slope was greater in high than in low responders (P = 0.044). In conclusion, lower peak torque, end-range torque and total angular impulse during eccentric contractions and a greater peak torque slope may identify high responders to eccentric exercise.     

Colour-based rigid body tracking using three-dimensional graphics models

This paper introduces the first stage of a new model-based approach to three-dimensional (3D) human movement tracking. A ‘generate-and-test’ matching procedure was adopted by matching rendered images of a 3D computer graphics model of the human body to target images of rigid body motion. The set of pixels to be compared were just those corresponding to the model of the body in the rendered images. The matching criterion to optimize model position and orientation was based on the minimisation of the RGB (red-green-blue) colour difference between generated model images and associated target images. The method was able to track synthetic image sequences of a half twisting somersault accurately with root-mean-square (rms) errors of less than 5 mm and 0.3∘ for position and orientation estimates respectively. The suitability of the proposed approach for rigid body motion tracking was supported by additional tracking experiments on video image sequences of ‘wooden cross’ trajectories. Comparisons of tracked estimates against manual digitizing estimates returned relatively small rms difference values on both side somersault and twisting somersault movements. The proposed approach has the potential to track video images of a human torso using a rigid body model and hence to track articulated movements by successively adding segments to the model in a hierarchical manner.     

THE INFLUENCE OF PERCEPTIONS OF MEDIA INFLUENCE: THIRD PERSON EFFECTS AND THE PUBLIC EXPRESSION OF OPINIONS

This paper explores the role of perceptions of the opinionsof others as they relate to the formation of public opinion.Two interrelated theories involving such perceptions, the thirdperson effect and the spiral of silence, are tested in the contextof public opinion regarding divestment of financial interestsin South Africa. As hypothesized by the third person effect, perceptions of theinfluence of media reports on others were found to be consistentlygreater than perceptions of influence on self. Findings werestrongly supportive of this component of the ‘third personeffect’ hypothesis. Perceptions of the opinions of otherswere also explored in relation to respondents' willingness toexpress their opinions publicly. As suggested by the spiralof silence theory, respondents were found to be more willingto express their opinions publicly when they perceived a trendin support of their viewpoint, or when there was a greater perceivedlikelihood of achieving success for their issue position. The size of the effect produced from joining these two processesis moderated by the role of issue salience. People perceivingdivestment as a highly important issue are more likely to ascribegreater media influence to others than to themselves, but theirwillingness to express their opinions publicly is least likelyto be influenced by perceptions of the climate of opinion.     

Across the desk: Teaching through independent study

As academic budgets become more stringent, independent study may provide curricular flexibility in higher education. This paper addresses independent study as a creative and alternative mode of learning. The authors explore its unique advantages and strengths, its planning and structure, the student/instructor interaction, the use of learning resources, examples of disciplinary and interdisciplinary approaches, the products of such study, and methods of evaluation.She is the co-editor ofThe Ghetto Reader and co-author of CAEL Institutional Report #2,Interpersonal Learning in an Academic Setting: Theory and Practice.Diana Worby is a Mentor in English and the Humanities at Empire State College, Suffern, New York, and teaches Freshman Composition at Rockland Community College.