New Books Briefly Noted

Abstract

Little research has investigated the observational learning process from a developmental perspective. The purpose of this study was to extend previous research by considering two factors: performance versus learning and sequencing versus form scores. Children 'N = 60) comprising two age groups (5-0 to 6-11 and 8-0 to 9-11 years) were randomly assigned to verbal rehearsal only, model only, or model plus verbal rehearsal conditions. The task was a 6 part motor skill sequence in which proper sequencing and quality of form were assessed. A 2 × 3 × 4 (age group by model type by trial blocks) repeated measures MANOVA revealed a significant three-way interaction. Older children performed equally well under any of the model type conditions during both performance and learning. For younger children, a model plus rehearsal was superior to rehearsal only on sequence and form at performance and learning and superior to model only on sequence scores during the first two performance trial blocks. Model only and model plus rehearsal conditions were equally effective on form scores. These results suggest that age differences exist in the modeling of motor skills under conditions varying in model type, sequence and form scores, and performance and learning phases.     

Epistemology and the Use of the .05 Level of Significance: A Rebuttal to Inductionism

In the first part of this study, the football potential of 67 football players was predicted from their scores on a football-potential test. The test battery consisted of motor ability items as well as football skill items. Substantial correlations were obtained between most test items and the test criterion, the sum of T scores. Size, as depicted by McCloy's classification index (C.I.), had a negative, nonsignificant correlation with the criterion. The discriminative power of the battery was evidenced by the highly significant correlation between the test criterion and the coaching staff's ranking of individual players (rho = .840). It was concluded that athletic potential in football can be predicted by testing. In the second part of the study, football teams from three different strata of competition were evaluated on the basis of the test battery. The battery substantiated a step-wise progression between the teams on most items, with significant differences being noted. The test showed validity, in that the test criterion (the sum of T scores) was significantly different between the teams.     

Age,Physical Activity,Physical Fitness,Body Composition,and Incidence of Orthopedic Problems

Abstract

The incidence of orthopedic problems was examined in 5, 582 men and women who attended the Cooper Clinic in Dallas, Texas between 1974 and 1982. The effects of age, physical activity, physical fitness, and body mass index (EMI) on the occurrence of these problems were examined using a proportional hazards approach. The expected risk of orthopedic problems per person-year was 0.045 for men and 0.046 for women. For men, physical fitness, BMI, and physical activity were associated with orthopedic problems, while for women, physical activity was the main predictor. Age was not a factor for either gender. The effect of change in physical fitness, physical activity, and BMI was examined in a subset of 2, 325 persons with more than one visit to the clinic. For women, physical activity and a decrease in BMI were associated with orthopedic problems, while for men none of those factors were significant. Again, age was not a factor in either group. The absence of any age effect on the occurrence of problems suggests that with regard to orthopedic problems, moderate amounts of physical activity in generally healthy persons may be recommended without special consideration as to age.     

Book Reviews

Abstract

Bard, Chantal, Fleury, Michelle, and Hay, Laurette (Eds.). Development of eye-hand coordination across the life span. Columbia: University of South Carolina Press, 1990. Pp. xii, 384. Figures, tables, references. Reviewed by Kathi Kamm, Indiana University.     

Physiological Responses to Maximal Treadmill and Handweighted Exercise

Abstract

The purpose of this investigation was to compare the peak physiological responses among four protocols that employed different amounts of handweighted exercise in 16 males (aged 26.3 ± 4.1 years). The four protocols were (a) uphill treadmill running (UR; 3.36 m-s¹, 2.5% grade increase-3 min¹); (b) uphill treadmill walking while pumping 1.36kg handweights (HW) (UWHW; 1.79ms¹, 5.0% grade increase-3 min¹; (c) treadmill walking while pumping .91-kg HW (WHW; 1.79 m-s¹, 0% grade, .91kg HW increase-3 min¹); and (d) standing in place and pumping HW (SHW; arm work as described in WHW). It was hypothesized that the peak responses would be inversely proportional to the estimated muscle mass activated (i.e., UR = UWHW > WHW > SHW). Dependent variables included peak oxygen uptake (VO₂ peak), peak heart rate (HRpeak), peak ventilation (V_epeak), and peak respiratory exchange ratio (RERpeak). No differences were noted between UR and UWHW with respect to any of the dependent variables. All variables (except RERpeak) were greater (p < .01) in UR and UWHW than either WHW or SHW. RERpeak was greater (p < .01) in UR and UWHW than in WHW. VO₂peak and HRpeak were greater (p < .01) in WHW when compared to SHW. Mean VO₂peak was 97.5, 69.7, and 60% of UR for UWHW, WHW, and SHW, respectively. Therefore, walking and pumping handweights provides a maximal stimulus to the oxygen transport system.     

The vibrational mode structure of a golf ball

In this paper, we report the discrete frequencies at which golf balls can vibrate, the mode patterns of these vibrations and how these modes can be excited. There are two broad classes of modes: those that radiate sound waves and those that do not. Both silent and acoustic modes are excited by tangential (i.e. spin-producing) impact forces; only acoustic modes are excited by radial impact forces. Exact analytical results for a homogeneous ball core are compared with finite element numerical results for both a core and a model two-piece ball. Correspondences are readily established for the important low-frequency modes, and the good agreement suggests the validity of these results for real golf balls. The results potentially provide the basis for a rapid, simple and non-destructive method of measuring the effective high-frequency elastic shear modulae of balls (and ball cores) as well as a method for 'tuning' the performance of balls for specific clubs. Some of these aspects are explored further in our companion paper in this issue.     

Effect of swimming velocity on arm coordination in the front crawl: a dynamic analysis

We examined the preferred mode of arm coordination in 14 elite male front-crawl swimmers. Each swimmer performed eight successive swim trials in which target velocity increased from the swimmer's usual 3000-m velocity to his maximal velocity. Actual swim velocity, stroke rate, stroke length and the different arm stroke phases were then calculated from video analysis. Arm coordination was quantified by an index of coordination based on the lag time between the propulsive phases of each arm. The index expressed the three coordination modes in the front crawl: opposition, catch-up and superposition. First, in line with the dynamic approach to movement coordination, the index of coordination could be considered as an order parameter that qualitatively captured arm coordination. Second, two coordination modes were observed: a catch-up pattern (index of coordination?=??8.43%) consisting of a lag time between the propulsive phases of each arm, and a relative opposition pattern (index of coordination?=?0.89%) in which the propulsive phase of one arm ended when the propulsive phase of the other arm began. An abrupt change in the coordination pattern occurred at the critical velocity of 1.8?m?·?s^?1, which corresponded to the 100-m pace: the swimmers switched from catch-up to relative opposition. This change in coordination resulted in a reorganization of the arm phases: the duration of the entry and catch phase decreased, while the duration of the pull and push phases increased in relation to the whole stroke. Third, these changes were coupled to increased stroke rate and decreased stroke length, indicating that stroke rate, stroke length, the stroke rate/stroke length ratio, as well as velocity, could be considered as control parameters. The control parameters can be manipulated to facilitate the emergence of specific coordination modes, which is highly relevant to training and learning. By adjusting the control and order parameters within the context of a specific race distance, both coach and swimmer will be able to detect the best adapted pattern for a given race pace and follow how arm coordination changes over the course of training.     

Trends in the Selection of Coaches for Female Athletes: A Demographic Inquiry

Abstract

Data were collected from 335 collegiate female athletic directors utilizing a questionnaire designed to assess trends in selecting coaches for female athletes between 1974 and 1979. These demographic results revealed: (a) a 37% increase in the number of coaches for female athletes, (b) a greater increase at the assistant (229%) rather than head (8%) coach level, (c) a substantial increase in male coaches (724) in comparison to their female counterparts (44), (d) a significant decline (294) in female head coaches, and (e) a large increase in the number of male head coaches (437). As the bases for this present investigation, current practices and affirmative action strategies were discussed (i.e., gender employment trends, de facto discrimination, federal civil rights legislation). Possible explanations of these findings were offered.     

Competition and Instructional Set Effects On the Speed and Accuracy of a Throwing Task

Abstract

Two experiments were conducted to investigate the effects of competition and instructional sets on the speed and accuracy of a dart-throwing task. In both experiments individuals competed against another subject on one day, and performed under noncompetitive conditions on a second day. The five distinct instructional sets varied from extreme emphasis on speed to extreme emphasis on accuracy. Multivariate analyses of variance revealed main effects for instructional sets on speed and accuracy in both experiments. Strong tradeoffs occurred with speed slowing and accuracy improving as the instructional emphasis changed from speed to accuracy. A competition by instructional sets interaction in Experiment 2 indicated that competition facilitated speed when speed was important, but when instructions emphasized accuracy, speed was slower in competition than in noncompetition. Accuracy was not affected by competition.     

The Effects of Age and Number of Demonstrations on Modeling of Form and Performance

Abstract

This study was designed to investigate the effects of age and number of demonstrations on both form (strategy employed) and physical performance on a Bachman ladder-balance task. College age (n = 60) and elementary age females (n = 60) were compared under four modeling conditions consisting of no, four, eight, and 12 demonstrations in an Age Group × Demonstration Group (2 × 4) MANOVA. Results indicated that college age students had higher performance and form scores than elementary age students. Only form differentiated the four demonstration groups. Participants receiving 12 demonstrations had higher form scores than the control participants. Form scores were analyzed in a discriminant function analysis to determine which of five form components differentiated the four demonstration groups. Results also revealed that climbing quickly was the component of form that differentiated the groups the most. It was concluded that matching form by the learner may be a more effective measure of modeling effects rather than inferring modeling from performance, especially in the initial stages of learning. In addition, it appears that the number of demonstrations needed to create modeling effects is task specific and dependent on the length of the practice period.