Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males

Abstract

Eighteen male subjects, ages 20–28 years, engaged in three fatigue bouts using an isokinetic dynamometer (Cybex II). Maximum knee extension contractions were given for 100 s at a rate of 30 per minute. The three contraction speeds chosen were 120° · s ^–1 160° · s ^–1 and 200° · s ^–1.Peak torque at 120° · s ^–1 was significantly greater (p <.05) than at 200° · s ^–1 for the first 60 s, and 160° · s ^–1 for the first 50 s. Thereafter, no significant differences existed among conditions. All three curves were found to follow two-component exponential functions as shown by the equation y_t =a ₂ e^k2^t – a ₁ e^k1^t + c. The three curves possessed similar rate constants for both components. Time to peak torque was achieved at similar times for testing at 160 and 200° · s ^–1 (p <.05). It is concluded that peak torque varies inversely with movement speed, and that the pattern of decrement is independent of movement speed. Time to peak torque does not appear to change significantly across trials in isokinetic fatigue.     

Cognitive Style and Learner Strategy Interaction in the Performance of Primary and Related Maze Tasks

Abstract

The effect of designated learning strategies and reflective versus impulsive cognitive styles on performance in a maze learning task was investigated. Twenty-four female subjects were randomly assigned to a strategy or control group. The strategies group was provided with three potentially effective strategies (imagery, rhythm, and feedback) as identified by an information processing task analysis procedure. The Matching Familiar Figures test further classified subjects within the two groups according to their preferred styles of responding. Eleven primary task trials were administered with direct view of maze and four related task trials were completed with an indirect view of it. Traversal speed and time in the incorrect pathways were analyzed with a 2 × 2 × 7 (Strategies × Cognitive Styles × Trial Blocks) repeated measures ANOVA. A significant three-way interaction was found for both dependent measures. As hypothesized, during the primary task the control reflective subjects traversed the maze more slowly than the control impulsive subjects. However, the strategies reflective subjects completed the maze with the same speed as strategies impulsives. The incorrect pathways × time interaction revealed that the control reflective subjects spent less time in the incorrect pathways during the related task than the control impulsives. No significant differences were found for strategies reflectives or impulsives. These findings indicate that, for this maze task that emphasized speed, the performance of reflective and impulsive subjects was facilitated by appropriate learning strategies.     

Differential Effects of Three Teachers Over a Unit of Instruction

The purpose of this study was to describe the effects of three teachers on psychomotor, affective, and cognitive outcomes over a 15-lesson volleyball unit. Three intact middle school physical education classes were used. Pre- and posttests were administered for the overhead set, forearm pass, and serve psychomotor skills. A semantic differential test with four affective dimensions and a written test on the rules, strategies, and mechanics of volleyball were also administered pre- and posttest. Data on instructional characteristics were obtained using academic learning time (ALT-PE); observation system for content development (OSCD-PE), and a content analysis of lessons.

The following were key aspects of the results: (a) Teachers differed in their approaches to the content of the unit more than in the characteristics of their instruction as determined through observational data; (b) teachers differed in respect to the psychomotor skills for which they were able to produce statistically significant student gain; (c) the skill level of students played a major role in psychomotor outcomes; (d) affective measures started high and remained high from pre- to posttest with significant change occurring positively with the low-skilled in one measure; (d) cognitive learning was significant from pre- to posttest in rules and mechanics but not in strategies. Instructional characteristics, as described in this study, did not change from skill to skill, but student learning did. This led the authors to conclude that the instrumentation for instructional variables was not sensitive to differences in the way individual skills were handled by individual teachers.     

Lactate and Phosphagen Levels in Muscle Immediately after a Maximum 300 m Run at Sea Level

Abstract

The relative effectiveness of six intensive training programs on the development of four selected skills was studied, with emphasis on limited time encountered within the semester organizational plan. One hundred and twenty college freshmen men volunteers were randomly assigned to training groups of 30 members each, which met for two sessions a week for 16 weeks.

Results indicated that: (a) direct practice jumping, alone or combined with repetitive sprinting or weight training, was significantly superior to weight training alone on standing broad jump development; (b) direct practice of a zigzag run was superior to both weight training and repetitive sprinting; and (c) when group acquisition of “adequate” skill is the objective, performance improvements educed over the first nine weeks were great enough to question the merits of persisting at an activity over a full semester. Only the zigzag run was adversely affected by the spring vacation cessation of training.     

Composition of Practice: Influence on the Retention of Motor Skills

Abstract

The purpose of these experiments was to investigate further the variable practice effect found by Shea and Kohl (1990). Experiment 1 was an initial attempt to determine the locus of the retention benefits demonstrated by subjects provided variable practice experiences. All groups received 20 acquisition blocks consisting of five test trials per block at a target of 150 N. The interval between test trials was either unfilled or filled, with additional trials consisting of the same target force, variable target forces, or practice on an unrelated motor task. The results indicated retention was not incremented (relative to an unfilled interval) by requiring subjects to perform an unrelated motor task in the intertest–trial interval. However, when the intertest–trial interval was filled with practice on related motor tasks, retention was significantly improved. Experiment 2 assessed the impact of increasing the number of related motor tasks interpolated between test trials. The results indicated filling the intertest–trial interval with one motor task resulted in large retention benefits relative to an unfilled interval. Further increases in the number of related motor tasks (3) interpolated between test trials resulted in only modest increments to retention. The results were consistent with the elaboration perspective proposed by Shea and Zimny (1983). The elaboration perspective proposes that the simultaneous presence of related items in working memory facilitates interitem elaborative and distinctive processing that ultimately results in retention benefits.     

Value Orientations of Preservice Teachers

Abstract

Curriculum theorists have acknowledged, the critical role that beliefs and values play in the decisions that teachers make, but very little is known about how teachers' value profiles develop. The purpose of this investigation was to examine the educational value orientations of a group of physical education preservice teachers (N = 16) enrolled in an elementary methods course and to investigate the link between value profiles and teacher behaviors. Value profiles were assessed using the Value Orientation Inventory (Ennis & Hooper, 1988). The results indicated that teachers in training entered field-based experiences with defined value profiles, but that these profiles were not stable constructs. Priorities within competing value orientations fluctuated over the course of a semester. Possible explanations for the changes that occurred and implications for teacher education programs are discussed.     

Effects of Proximity on the Choice to Be Physically Active or Sedentary

The link between physical activity and weight loss has precipitated interest in interventions to foster adherence to exercise. It has been suggested that treatment effects, when significant, should be analyzed to determine theory-based mediators. This research assessed possible mediation of changes in Physical Self-Concept, Exercise Self-Efficacy, Total Mood Disturbance, and Body Areas Satisfaction scores on the relationship between exercise session attendance and participation by obese women in a 6-month treatment based on tenets of social cognitive theory (n = 73) or a control condition (n = 64). Participation in the treatment was associated with significantly greater exercise session attendance and significantly greater improvements in Physical Self-Concept, Exercise Barriers Self-Efficacy, and Body Areas Satisfaction. Overall, changes in the assessed psychological factors demonstrated significant mediation of the association between group membership and exercise session attendance, R² = .23, with only change in Physical Self-Concept scores providing a significant unique contribution. Extensions of this research across different sample types, and with longer durations, were suggested to refine theory and, ultimately, improve exercise adherence treatments.     

Use of NSE/PS2m-transgenic mice in the study of the protective effect of exercise on Alzheimer's disease

In its late stage, Alzheimer's disease results in progressive muscle weakness in the arms and legs. The aim of this study was to determine whether mice expressing the skeletal muscle-specific mutant PS2 gene (a model of Alzheimer's disease) are a useful experimental system to study the protective effect of exercise on Aβ-42 reduction, improvement of behavioural function and changes in metabolic parameters. With this aim in mind, the transgenic mice were subjected to treadmill exercise for 3 months. The results showed that in transgenic mice, but not in normal mice, treadmill exercise resulted in a reduction of Aβ-42 deposits and an improvement in behavioural function, thereby restoring normal concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride. Thus, exercise may represent a practical therapeutic strategy for use with human patients with Alzheimer's disease.     

Stress in elite sport performers: A comparative study of competitive and organizational stressors

The purpose of this study was to compare the content and quantity of competitive and organizational stressors in elite athletes. Ten international performers were interviewed about sources of stress. Content analysis of the data involved categorizing the demands associated primarily and directly with competitive performance (#CS = 21) under the post hoc dimension “performance issues”, and the demands associated primarily and directly with the sport organization (#OS = 72) under one of the following four post hoc dimensions: “environmental issues”, “personal issues”, “leadership issues” and “team issues”. Frequency analysis revealed that the participants mentioned the competitive stressors (Σ = 95) less than the organizational stressors (Σ = 215). Further analysis within these categories showed that the mean number of participants citing individual competitive stressors (M = 4.52) was greater than the mean number of participants citing individual organizational stressors (M = 2.99). The findings indicate that elite athletes experience and recall more demands associated primarily and directly with the sport organization than with competitive performance. Furthermore, this population appears more likely to mention similar competitive stressors but varied organizational stressors, probably because the former are inherent and endemic to elite sport, whereas the latter are essentially extraneous and widely distributed.