Effects of Overload Training on Velocity and Accuracy of Throwing

Abstract

Twenty-one male freshmen baseball players at the University of Maryland were randomly placed in three groups of equal size. Two groups supplemented a baseball throwing program by specific overload training. One group threw weighted baseballs while the other used a pulley device to resist the mechanics of throwing. Training was carried out for a 6-week period. Both training groups experienced significant within-group increases in throwing velocity as a result of training, with no significant change in accuracy. However, no significant difference was indicated among training groups and a control group.     

Relationship between Ability to Perform Tumbling Skills and Ability to Diagnose Performance Errors

Abstract

The purpose of this study was to determine the relationship between the ability to perform 11 tumbling skills and the ability to diagnose errors of execution in the performance of these same skills. Thirty-two male upper divisional physical education majors at the University of Maryland served as subjects. A knowledge test was administered to the subjects to determine their knowledge of the mechanics of execution for each skill. The subjects' performances of these tumbling skills were photographed and evaluated by expert judges. The subjects diagnosed errors in the execution of each of the 11 skills from a cinematographic presentation of demostrator performances. A significant correlation as expressed by an r = .49 was found between performance ability and diagnostic ability with a significant correlation coefficient of .51 between knowledge and diagnostic ability, however, no significant relationship was indicated between performance ability and knowledge.     

Effects of Food Supplement on the Performance of Selected Gross Motor Tests

Abstract

The purpose of this investigation was to study the effect of a well-advertised vitamin-mineral supplement on three selected gross motor tests. Experimental and control groups were formed in two groups, football players and physical education majors. Measurements were taken at five different time periods covering a period of 12 weeks. No statistically significant differences in motor performance were found between those subjects taking the supplement and those taking the placebo.     

On the Pedagogy of Feedback Systems

The undergraduate student contacts feedback ideas from two distinct points of view, each with its own nomenclature and symbolism: electronics on one hand, and control systems on the other. In the typical electronics or communications book treating feedback at an undergraduate level, the analysis is constrained to the steady-state sinusoidal situation. Nyquist's criterion is merely presented without proof or justification. The student finds this theorem, when presented so briefly, a rather mysterious and vague concept. On the other hand, the author of the control systems or servo-mechanism text gives space in his book for a more thorough treatment of the feedback system but usually he uses terms and symbols that to the student seem to be unrelated to those terms and symbols used in the electronics "brand" of feedback. In recent years, the pole-zero concept has become a part of the undergraduate student's background in circuits. Pedagogically, the root-locus approach to the feedback system follows with ease. In contrast, Nyquist's criterion definitely becomes the more difficult concept. Furthermore, the root-locus approach is broader in scope. From three to fifteen lectures are needed to bridge the gap between the pole-zero concepts of circuits to a basic understanding of the feedback system.