Biomedical subjects
Publications and source records attributed to D Southard.
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The purpose of this study was to determine if change in segmental mass and increases in throwing velocity act as control parameters to alter throwing patterns. Twenty participants were categorized into four levels of throwing pattern. Each participant was required to make 10 throws at various velocities within 8 conditions. Conditions resulted from combinations of altered mass of the arm, forearm, and hand. Quantitative and qualitative analyses indicated that changes in segmental mass and release velocity either increased or decreased levels of throwing pattern depending on the initial throwing level. It was concluded that mass and velocity may be control parameters which instigate changes in throwing patterns.
The purpose of this study was to determine: (a) if preperformance behaviors display a consistent rhythm across disparate activities; and (b) the relationship of periodicity for such preperformance routines to successful performance. Seven male volunteers were subjects for this study. Each subject had an established ritual for golf putt, basketball free throw, and tennis serve. Data were collected with a motion-analysis system and video camera while the subjects performed each activity. Dependent measures were types of preperformance behaviors, absolute timing of behaviors, relative timing of behaviors, differences in relative times across activities, and successful performance, and mechanical variables related to performance. Analysis of variance (Subject x Activity) indicated significant main effects and interactions for absolute and relative timing of behaviors. Significant correlations were determined to exist between relative time and success, and differences were found between relative times across activity and successful performance. It was concluded that rituals result from endogenous rhythms and that stable periodicity of behaviors across activities promotes successful performance.
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The purpose of this study was to determine the importance of timing during an auto-communicative ritual to successful performance. Eight members of a university varsity basketball team served as subjects for this study. Each subject performed 15 free throws in each of four different conditions. Condition 1 required subjects to use their standard free throw ritual prior to shooting. Condition 2 required subjects to maintain the relative timing of ritual behaviors but reduce the absolute time of the ritual by one-half. Condition 3 required that relative timing be maintained but that the absolute time of the ritual be doubled. Condition 4 required the same behaviors and the same absolute time as the standard ritual but that the relative time of the ritual be altered. Data were collected with a 16-mm high-speed camera. Types of behaviors, timing aspects of the ritual, successful attempts, and shot mechanics were dependent measures. Analysis of variance (ANOVA) of dependent measures and Fisher's scores from correlation coefficients of dependent measures indicate that relative timing of behaviors (rhythmicity) is more important to success than the absolute time of rituals. Behaviors most important to free throw success are those that may be totally controlled by the subject and yet remain stable with changing conditions.
The purpose of this study was to determine the nature and effect of certain highly patterned behaviours utilized prior to free-throw shooting in basketball. Ten female basketball players comprising the varsity squad of Texas Christian University, Fort Worth, Texas, USA served as subjects for this study. Subjects were filmed with a high-speed camera and monitored for heart rate during the performance of 10 free throws in each of two conditions: ritual and non-ritual. For the ritual condition, subjects were given unlimited time and freedom of movement prior to each free-throw attempt. For the non-ritual condition, subjects were not restricted by time, but were instructed to shoot the ball without utilizing any movements other than those required to project the ball to the goal. Dependent measures were characteristics of behaviours, physiological changes measured by heart rates, mechanical data (speed, height and angle of release), and number of successful attempts. Condition x trials analyses of variance and low standard deviation concerning characteristics of behaviours indicated that the idiosyncratic behaviours prior to free-throw shooting were rituals of the auto-communicative type. Results indicated no significant difference between conditions for free-throw success. However, partial correlation between dependent measures and successful free-throw attempts indicated that duration of behaviours was most crucial to free-throw shooting success.
This study investigated the changes in an arm striking pattern as a result of practice and the effects of speed and accuracy requirements on such changes. The task was to strike a baseball-size foam ball from a batting tee adjusted to the height of each subject's iliac crest. Ten righthanded subjects, initially displaying an inefficient striking pattern, volunteered for this study. All subjects performed the task according to the following conditions: (1) speed, (2) accuracy, and (3) speed and accuracy. Each subject completed 10 trials in each condition (randomly ordered) for five consecutive days. A high-speed camera (64 fps) was used to photograph subjects' striking patterns for each condition over the 5-day period. Analysis of variance of joint angles at arm reversal and contact and velocity of hand relative to the glenohumeral axis at contact revealed that subjects initially constrained limb segments to act in a unitary fashion; then, with practice, a more efficient pattern was developed. The requirement of speed was found to enhance a change in limb configuration, whereas the requirement of accuracy, and subsequent reduction in speed, impeded the development of a more efficient striking pattern. Analysis of radial error revealed no differences in accuracies to the target by either condition or day of practice. A graphic analysis of segmental angular momentum versus relative time showed that joint angle changes allowed subjects to transfer angular momentum and thereby increase the velocity of the hand at contact.
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