Research on Tai Chi as a sport in health care

This article examines the content and methodology of studies on Tai Chi as a sport in health care. We investigate the concept behind the rather simple name “Tai Chi,” concluding that this concept is manifold and highly variable. How did researchers deal with this variability when studying the effects of Tai Chi as a health-care intervention? We then explore how scientific research on Tai Chi has been conducted to date and draw the interim conclusion that the variability was barely taken into consideration. Our analysis of seven Tai Chi interventions reveals that two interventions referred to as Tai Chi may differ considerably in their content. The variability poses difficulty in repeating the intervention and drawing causal inferences. This problem is discussed in the current literature under the term “complexity in health-care interventions.” On the basis of a summary of this debate, we discuss the challenge of researching Tai Chi from a complex perspective—with the aim of achieving solid results that can be repeated.     

The weight of expectation: Cathy Freeman,Legacy, Reconciliation and the Sydney Olympics – A Canadian Perspective

This paper compares French- and English-language Canadian television coverage of Australian Aboriginal athlete Cathy Freeman during the 2000 Olympics using a narrative framework. The specific focus of the analysis is the representation of Freeman's political identity as an agent and symbol of Aboriginal reconciliation – the struggle for apology, reparatio, and social justice in the light of the history and legacy of colonial oppression and exclusion. Freeman has used her sporting success to signify visibly and with some controversy her identification with political Aboriginality and reconciliation, and she went into the 2000 games bearing an unusual weight of expectation, intensified by being chosen to light the Olympic cauldron, that a victory in the 400 metres would mark symbolically reconciliation between Aboriginal and non-Aboriginal Australians. The analysis generally conforms the hypothesis that the normative dimension of these expectations would be accentuated more in the French- than English-language coverage, and this resulted in a more consistently affirmative portrayal of Freeman and her performance. The English-language coverage emphasized the ambivalent nature of her role. The corollary of this was that the English-language coverage paid greater attention to the substance of Aboriginal grievances and struggle. Nonetheless, neither network saw Freeman's identity in openly critical terms: in Freeman's Olympic narrative sport and politics were allowed to mix in a relatively unproblematic way.     

The effects of training on performance and performance-related states in individual elite athletes: A dynamic approach

Abstract

There are difficulties undertaking controlled training studies with elite athletes. Thus, data from non-elite performers are often presented in scientific journals and subsequently used to guide general training principles. This information may not be transferable or specific enough to inform training practices in an individual elite athlete. However, the nature of athletic participation at elite levels provides the opportunity to collect training data, performance-related variables, and performance data of elite athletes over long periods. In this paper, we describe how dynamic linear models provide an opportunity to use these data to inform training. Data from an elite female triathlete collected over a 111-day training period were used to model the relationship between training and self-reported fatigue. The dynamic linear model analysis showed the independent effects of the three modes of triathlon training on fatigue, how these can change across time, and the possible influence of other unmeasured variables. This paper shows the potential for the use of dynamic linear models as an aid to planning training in elite athletes.     

Offside decision making of assistant referees in the English Premier League: Impact of physical and perceptual-cognitive factors on match performance

Abstract

In the present study, we investigated the accuracy of offside judgements of assistant referees in the English Premier League. The moment in the match, the position and movement speed of the assistant referee, attacker and second-last defender, together with the angle of view for the assistant referee were all considered to underlie incorrect decisions. The error rate was 17.5% (868 of 4960 situations). As the English assistant referees tended not to signal in doubtful situations (c = 0.91), there was an overall bias towards non-flag errors (773 non-flag errors vs. 95 flag errors). The flash-lag hypothesis could explain all flag errors, whereas the optical-error hypothesis could explain a proportion of the non-flag errors (45.4%). Fatigue, movement speed, and angle of view did not have a detrimental effect on offside decision making. In conclusion, there were fewer flag errors than in the 2002 and 2006 FIFA World Cups, whereas the number of non-flag errors rose. The increased awareness of factors involved in offside decision making and the instructions to give the benefit of the doubt to attackers could have contributed to this situation.     

Biomechanical loading of the hip during side jumps by soccer goalkeepers

Abstract

There is a risk of hip injury in dives to the side by soccer goalkeepers. In this study, we assessed hip loading in goalkeepers when performing such dives. The experiments were conducted in a laboratory setting using an in-ground force plate as well as on a grass surface when the athletes were equipped with force sensors. The forces acting on the hip were measured and high-speed video analysis was performed, allowing the investigation of the dive characteristics and techniques. The peak force values recorded in the laboratory setting ranged from 3 to 8 kN, which corresponded to 4.2–8.6 times body weight. The vertical impact velocities reached 3.25 m · s^?1. In the field experiments, a hip loading of 87–183 N · cm^?2 was determined. We found that goalkeepers who perform a rolling motion reduce their hip loading. The data provided by this study add to the biomechanics database and contribute to the establishment of injury criteria. Such information is necessary to develop and implement strategies to help prevent hip injuries.     

A Nomogram for the Estimate of Percent Body Fat from Generalized Equations

Abstract

Fifteen well-conditioned college women, who had been thoroughly trained in the correct technique for women's push-ups, were tested for maximal pushing strength in two positions and for the number of complete push-ups they were able to perform at the rate of 41 push-ups per minute. For statistical purposes, calculations of maximal strength for each individual were based upon the average of the recorded maximal arm strengths in the high and low positions plus the average of the weight supported in the high and low positions. The work load was calculated from the distance between the high and low positions, the average supported weight, and the number of push-ups the subject was able to perform until exhausted. A correlation coefficient of .76 was obtained between the calculated maximal strength measures and the work load, indicating a statistically significant positive relationship.     

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.     

Cardiac Dimensions in Elite Young Track Athletes

The purpose of the study was to compare young sprint and distance runners for changes in their cardiac dimensions with increased age (10–17 years) or body surface area (1–2 m²). Echocardiographic dimensions were obtained on 73 male track athletes competing in the 1983 National Age Group Track and Field Association championships. Each group of athletes was also compared with a hypothetical normal population (matched for weight and age) generated from prediction equations derived by Henry, Gardin, & Ware (1980). The cardiac dimensions examined were: Left ventricular internal diameter, left ventricular posterior wall thickness, and interventricular septum thickness. The male distance runners (n = 38) had a significantly greater increase in left ventricular posterior wall thickness and interventricular septum thickness with increasing age or increasing body surface area compared to the sprinters (n = 35) or compared to the predicted normal population. The left ventricular internal diameter was not significantly different between the groups. These results indicate that the hearts of male distance runners are undergoing a training hypertrophy whereas the hearts of sprinters are no different than hearts in a normal population. The changes in cardiac dimensions of these young athletes run counter to the generalizations stated for adult athletes: That endurance training enlarges the left ventricular internal diameter, but does not increase the left ventricular posterior wall or interventricular septum thickness.