Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players

Abstract

We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.     

Ball launch conditions for skilled golfers using drivers of different lengths in an indoor testing facility

Abstract

The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors.     

Stimulus Velocity,Duration and Uncertainty as Determiners of Response Structure and Timing Accuracy

Abstract

The present experiments examined the effects of stimulus velocity, stimulus duration, and stimulus uncertainty on the spatial-temporal structure and timing accuracy of coincident timing responses. The results of Experiment 1 indicated that the response structure for aimed movements differed from that of ballistic movements but response accuracy was comparable for both movement conditions. However, when information concerning the stimulus velocity was provided, the responses to the faster stimuli (i.e., stimuli of shorter duration) appeared to be “speeded up” copies of those to slower stimuli and response accuracy increased as the stimulus velocity increased (i.e., stimulus duration decreased). When the stimulus velocity was not known, subjects initiated a common response for approximately 260 msec and response accuracy appeared to decrease as the stimulus velocity increased (i.e., stimulus duration decreased). Experiment 2 indicated that the stimulus duration rather than the stimulus velocity was the major determiner of both the spatial-temporal structure and timing accuracy and that a very fast and a very slow stimulus will be responded to similarly when the stimulus duration remains constant.     

Multiplicative Measurements of a Trait Anxiety Scale as Predictors of Burnout

The purpose of the present study was to investigate whether combining the two dimensions of anxiety (i.e., intensity and direction) by using a multiplicative model would strengthen the prediction of burnout. Collegiate athletes (N = 157) completed the Athlete Burnout Questionnaire as well as a trait version of the Competitive State Anxiety Inventory-2D. Three separate hierarchical regression analyses with four blocks were conducted to predict each one of the burnout subscales from anxiety intensity and direction while controlling for gender. The multiplicative variable for cognitive anxiety was a significant predictor of reduced sense of accomplishment (p < .01). Self-confidence was the only directional scale that predicted reduced sense of accomplishment, emotional/physical exhaustion, and devaluation (p < .01). In addition, gender was found to predict overall burnout in all three subscales as a control variable (p < .05). Conclusions and applied implications are drawn based on the results.     

Exercising with Passion: Initial Validation of the Passion Scale in Exercise

Adequate response to mail health surveys by minority populations has proved problematic. The impact of mail survey design features utilized to promote Orthodox Jews' responses (N = 138; 82 eligible synagogue member households) to a mailed questionnaire used to measure walking behavior are described and assessed. An examination of response characteristics by wave as an estimate of nonresponse bias and calculations of response speed and cost-effectiveness were conducted. Response rates of 54.8% and 52.9% for eligible households and individuals, respectively, were accumulated by using 9 of 14 recommended mail survey techniques for this particular population (e.g., culturally appropriate salutation and closing, religious iconography, Talmudic aphorisms, and incentives linked to Hebraic numerology and the synagogue's building fund). Nonrespondents most frequently cited business, forgetfulness, or lack of topic salience as reasons for not responding. No differences on sociodemographic items and 9 of 11 continuous variables were observed by response wave; response speed was slowest in response to later mailing waves; and cost-effectiveness was maximal during postcard follow-up (E statistic = 3.74). Nonresponse bias may not be problematic with a > 50% response rate in this particular population. Front-loading incentives may prompt quicker response and improve cost-effectiveness. Specific design considerations for future consideration and testing are provided.     

Physical activity in the lives of Hong Kong Chinese children

To understand the physical activity culture in the lives of Hong Kong Chinese children and their parents, 48 young people between the ages 9 and 16 and their parents, with different socio-economic backgrounds and geographical locations, were interviewed for this study. By applying Confucianism and postcolonialism, this study aimed to investigate the meaning of physical activity in the lives of Hong Kong children and their parents. The results showed that parents value physical activity as a factor which contributes to their children's well-being and provides balance to their life. There were differences though, in this attitude, for different age groups. Junior students (aged 9–12) expressed their interest in physical activities. However, older students (12 or above) in secondary school, think or are told that academic study is the most important aspect of their life and that physical activities are not a priority. When examining parents' and children's involvement in physical activity, the barriers to the parents' involvement in their children's physical activities included lack of time and a habitual sedentary lifestyle at home.     

‘Governmentality’ in the origins of European female PE and sport: the Spanish case study (1883–1936)

The purpose of the paper is twofold: (1) to contribute to the analysis of the origins of modern European female PE and sports from a power perspective, inspired by Foucault's work; and (2) to present a detailed analysis of female PE and sport in Spain (1883–1936) as a specific European case study. It is argued that these physical activities could be conceived in the Spanish case as part of a specific kind of ‘governmentality’ with a dual nature. On the one hand they represented disciplinary ‘technologies of power’ over the female body. Selected physical activities—dictated mainly from the hygienic-moral position of the Regeneracionistas (‘Regenerationists’)—were exerted as a kind of ‘bio-power’ for the control of the female population. On the other hand, such kind of activities (especially sports) represented certain ‘technologies of the self’ for middle and upper class women. Through participation in sports, women gained a more active and public role in the Spanish society of the era, obtaining some degree of autonomy in self-governance over their bodies and their lives.     

Youths with migration backgrounds and their experiences of physical education: an examination of three cases

While understanding young people has never been easy, migration trends make it increasingly difficult. Many classrooms have become culturally heterogeneous and teachers are often faced with pupils with diverse linguistic and cultural heritages. Current scholarship suggests that as a discipline, physical education has not adapted to this diversity. In fact, commentators have suggested that physical education alienates pupils from minority groups and that traditional practices work to maintain cultural difference. The broad objective of this paper is to provide insights into how physical education intersects with biographies shaped by migration. Drawing from a case study investigation, this paper presents interview data from three youths with migration backgrounds living in a German-speaking region of Switzerland. The cases were selected because they highlight various ways in which physical education (PE) comes to make sense for adolescents. The key arguments that we develop are that ethnicity often works at an implicit level in PE, that young people experience the effects of migration backgrounds in diverse ways, and that migrants themselves support official educational discourses that work to disadvantage people with migration backgrounds. A key implication is that in a cultural milieu in which generalisations are normal and sometimes considered desirable, both researchers and practitioners need to be wary of racialising discourses. As an alternative, it is suggested that focusing on individual processes can improve the conceptualisation and implementation of physical education pedagogies.     

Effectiveness of Rest,Abdominal Cold Packs,and Cold Showers in Relieving Fatigue

Abstract

The purpose of this study was to compare three methods of relieving fatigue between bouts of strenuous exercise—rest, abdominal cold packs, and cold showers. Fifteen subjects were used in the study; each subject participated in each of the three treatments, making a total of 45 measurements. The subjects ran on a treadmill which was set at 8 mph with a 10 percent elevation, until their pulse rates reached 180 beats per minute. One of the three treatments was then applied for 10 min., after which the subjects engaged in a second treadmill run until heart rates reached 180 beats per minute. The time of the second treadmill run was the main criterion measure.

A complete randomized block design was used to test the differences among the three treatments for statistical significance. The Newman-Keuls sequential range test was employed to test differences between all possible pairs of treatment. Abdominal cold packs proved to be the most effective treatment, with the cold shower second and rest third.