Dan Southard

Warm-Up with Baseball Bats of Varying Moments of Inertia: Effect on Bat Velocity and Swing Pattern

Abstract The purpose of this study was to determine if warm-up with baseball bats of different moments of inertia has an effect on swing pattern and bat velocity. Ten experienced baseball players (ages 20–25 years) voluntarily participated in this study. Each participant was required to complete 10 dry swings (5 warm-up and 5 postwarm-up) at maximum effort within 3 different conditions. Post warm-up was always with a standard bat (I = .27 kgm2; 83.8 cm, 9.1 N). Warm-up for Condition 1 was with the standard bat. Condition 2 required participants to warm up with a standard bat plus a 6.1 N lead donut (I = .49 kgm2, 83.8 cm, 15.6 N). Condition 3 required participants to warm up with a hollow plastic bat (I = .08 kgm2; 83.8 cm, 3.34 N). Quantitative and qualitative analyses indicated that following warm-up with the weighted bat (largest moment of inertia), swing pattern was significantly altered, and post warm-up velocity was the lowest of the three conditions.

Rhythmicity, Ritual, and Motor Performance: A Study of Free Throw Shooting in Basketball

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 Fishers 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.

Mass and Velocity: Control Parameters for Throwing Patterns

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.

Change in Throwing Pattern: Critical Values for Control Parameter of Velocity

Abstract The purpose of this study was to determine the critical values at which throwing patterns change when scaling up on the control parameter of velocity. Thirty-six participants (ages: 6–12 years) were categorized into four throwing levels according to patterns represented by temporal joint lag. Each participant was required to complete 5 overhand throws at each of 10 relative velocities for a total of 50 trials per participant. The lowest velocity was 10% of maximum, with increases in increments of 10% up to a maximum effort. Quantitative and qualitative analyses indicated that critical values varied according to throwing category and joint. Generally, lower skilled throwers (Levels 1 and 2) had less stable joint lag and changed patterns at lower velocities than higher skilled (levels 3 and 4) throwers.

Attentional focus and control parameter: effect on throwing pattern and performance.

In two separate experiments, this study examined changes in motor pattern and performance accuracy when low-level throwers focused on internal variables, external variables, and/or velocity of throw. In Experiment 1 the task goal was to improve the throwing pattern. In Experiment 2 the task goal was to throw as accurately as possible at a target. The results of Experiment 1 indicated that increasing velocity was most effective for changing the throwing pattern, with external focus more effective than internal focus. The results of Experiment 2 indicated that external focus was the most accurate condition and increasing velocity was most effective for changing the throwing pattern.

Rhythmicity and Preperformance Ritual: Stabilizing a Flexible System

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.

Changing Throwing Pattern: Instruction and Control Parameter.

The purpose of this study was to determine the effects of instruction and scaling up a control parameter (velocity of throw) on changes in throwing pattern. Sixty adult female throwers (ages 20-26 years) were randomly placed into one of four practice conditions: (a) scale up on velocity with no instruction, (b) maintain constant velocity with no instruction, (c) maintain constant velocity with instruction, and (d) scale up on velocity with instruction. Participants in each condition were required to practice throwing with the nondominant arm twice per week for 5 weeks (10 sessions). Practice consisted of 20 throws per session. Participants in conditions including instruction were encouraged to rotate the trunk in an attempt to take advantage of the order parameter. Analysis indicated that each condition improved relative to use of the open kinetic chain. However, participants who increased velocity were more likely to attain maximum use of the order parameter with less practice. Additionally, throwers who increased velocity without instruction attained an optimal pattern of complete distal lag one session earlier than those who increased velocity with instruction. Data indicated that for those conditions without instruction, hand to forearm lag (H-F lag) occurred before humeral lag. It was concluded that emphasizing proximal movement (trunk rotation) without increasing velocity does not result in a final pattern that uses H-F lag.

Ritual and free‐throw shooting in basketball

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.

Throwing Pattern: Changes in Timing of Joint Lag According to Age Between and Within Skill Level

Accomplished throwers conserve angular momentum when distal joints of the throwing arm reach peak velocity at a later time than their proximal neighbors. The result is an increase in velocity of the most distal segment—the hand. Past research indicates that skill level varies by the number of joints experiencing distal timing lag (time to peak velocity of a distal joint minus the time to peak velocity of its proximal neighboring joint) and that the amount of lag may vary within skill level across individual performers (Southard, 2002). The purpose of this study was to determine if the amount and variance of joint timing lag differ between and within skill level and age of performer. Eighty participants were divided into four groups according to their age and skill level. Participants were required to throw a ball at 50% maximum velocity. Differences in the timing of three-dimensional joint lag were determined using a 2 x 4 (Age x Level) multivariate analysis of variance (MANOVA). Significant MANOVA was followed by discriminant function analysis, univariate analysis of variance (ANOVA), and analysis of covariance. Coefficient of variance in joint lag was analyzed using separate 2 x 4 ANOVAs. MANOVA results indicated a significant two-way interaction. Discriminant analysis showed that wrist lag was the best discriminating variable for age. Wrist and elbow lag were best for throwing level. ANOVA for wrist lag indicated a decrease in distal timing lag for older and higher level throwers. Elbow lag increased with age and skill level. Coefficient of variance results indicated that joint lag for younger and lower level performers was most variable. It was concluded that such differences in lag should be considered when defining throwing performance.

Changes in Kicking Pattern: Effect of Experience, Speed, Accuracy, and Effective Striking Mass

Purpose The purposes of this study were to: (a) examine the effect of experience and goal constraints (speed, accuracy) on kicking patterns; (b) determine if effective striking mass was independent of ankle velocity at impact; and (c) determine the accuracy of kicks relative to independent factors. Method Twenty participants were recruited to kick at 3 different velocities with and without an accuracy requirement. Multivariate analysis of variance determined if relative timing of joint angular velocities changed during the kick. Chi-square analysis determined if calculated effective mass was independent of ankle velocity at impact. Analysis of variance (ANOVA) was used to examine differences in absolute constant error and variable error according to independent factors. Results Results indicated that experience and speed affect absolute timing of joint velocities with no changes in the relative timing of peak joint velocity across independent factors. Chi-square analysis indicated that calculated effective mass is not independent of ankle velocity. ANOVA indicated that experienced performers displayed less variability error than did inexperienced performers. Conclusion It was concluded that: (a) Experience, velocity, and accuracy do not affect the relative timing of kicks; (b) kickers trade ankle velocity at impact for greater effective striking mass and ball velocity; and (c) variability in ball placement is affected by experience.