Physiological and metabolic responses of wheelchair athletes in different racing classes to prolonged exercise

The aims of this study were to examine and compare selected physiological and metabolic responses of wheelchair athletes in two paraplegic racing classes [T3: n = 8 (lesion levels T1-T7; paraplegics); T4: n = 9 (lesion levels below T7; paraplegics)] to prolonged exercise. In addition, we describe the responses of three tetraplegic athletes [T2: n = 3 (lesion levels C6/C7: tetraplegics)]. Twenty athletes completed 90 min of exercise at 75% VO2peak on a motorized treadmill adapted for wheelchairs. The mean (+/- s) heart rates of the T3 and T4 racing classes were 165 +/- 2 and 172 +/- 6 beats.min-1, respectively. For the T4 racing class, heart rate gradually increased during the test (P < 0.05), whereas for the T3 racing class, heart rate reached a plateau after an initial increase. The mean heart rate of the tetraplegics was 114 +/- 3 beats.min-1. The T3 and T4 classes exhibited similar respiratory exchange ratios, plasma lactate and glucose concentrations throughout the test. For both the T3 and T4 racing class, free fatty acid, glycerol, ammonia, urea and potassium concentrations had increased from resting values by the end of the test (P < 0.05). In conclusion, the results of this study suggest that endurance-trained wheelchair athletes are able to maintain velocities equivalent to the same relative exercise intensity (75% VO2peak) for prolonged periods irrespective of lesion level.     

Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion

In this study, we assessed the validity and reliability of 5 and 10 Hz global positioning systems (GPS) for measuring instantaneous velocity during acceleration, deceleration, and constant velocity while straight-line running. Three participants performed 80 running trials while wearing two GPS units each (5 Hz, V2.0 and 10 Hz, V4.0; MinimaxX, Catapult Innovations, Scoresby, VIC, Australia). The criterion measure used to assess GPS validity was instantaneous velocity recorded using a tripod-mounted laser. Validity was established using the standard error of the estimate (± 90% confidence limits). Reliability was determined using typical error (± 90% confidence limits, expressed as coefficient of variation) and Pearson's correlation. The 10 Hz GPS devices were two to three times more accurate than the 5 Hz devices when compared with a criterion value for instantaneous velocity during tasks completed at a range of velocities (coefficient of variation 3.1-11.3%). Similarly, the 10 Hz GPS units were up to six-fold more reliable for measuring instantaneous velocity than the 5 Hz units (coefficient of variation 1.9-6.0%). Newer GPS may provide an acceptable tool for the measurement of constant velocity, acceleration, and deceleration during straight-line running and have sufficient sensitivity for detecting changes in performance in team sport. However, researchers must account for the inherent match-to-match variation reported when using these devices.     

The Prosocial and Antisocial Behaviour in Sport Scale: Further evidence for construct validity and reliability

Abstract

The purpose of this research was to provide further evidence for the construct validity (i.e., convergent, concurrent, and discriminant validity) of the Prosocial and Antisocial Behaviour in Sport Scale (PABSS), an instrument that has four subscales measuring prosocial and antisocial behaviour toward teammates and opponents. We also investigated test-retest reliability and stability of the PABSS. We conducted three studies using athletes from a variety of team sports. In Study 1, participants (N = 129) completed the PABSS and measures of physical and verbal aggression, hostility, anger, moral identity, and empathy; a sub-sample (n = 111) also completed the PABSS one week later. In Study 2, in addition to the PABSS, participants (N = 89) completed measures of competitive aggressiveness and anger, moral attitudes, moral disengagement, goal orientation, and anxiety. In Study 3, participants (N = 307) completed the PABSS and a measure of social goals. Across the three studies, the four subscales evidenced the hypothesised relationships with a number of variables. Correlations were large between the two antisocial behaviours and small between the two prosocial behaviours. Overall, the findings supported the convergent, concurrent, and discriminant validity of the scale, provided evidence for its test-retest reliability and stability, and suggest that the instrument is a valid and reliable measure of prosocial and antisocial behaviour in sport.     

Coaching efficacy research: learning from the past and looking to the future

Coaching efficacy (CE) represents the extent to which coaches believe they have the capacity to affect the learning and performance of their athletes, and the CE model details antecedents, dimensions and outcomes of CE. Based around the CE model, the present paper had two main aims. First, to present a comprehensive and critical review of the research underpinned by the CE model. Studies were categorised by whether they investigated antecedents, outcomes or athletes’ perceptions of their coach. Twenty-one published studies were identified for the review. Overall the review provides support for the main tenets of the CE model, with researchers establishing links between CE and many of the antecedents and outcomes proposed in the model. The second aim was to assimilate findings from the review, limitations in the CE model and relevant conceptual models to present a revised CE model. Whilst retaining the essence of the original model, the revised model also incorporates explicit processes linking coach beliefs and athlete perceptions, antecedents of athlete perceptions and an intrarelationship source of CE. It also incorporates specific categories of coach behaviour and athlete-/team-level outcomes. The paper concludes by identifying limitations in the literature and review, and by proposing key directions for future research.     

The Development of the Olympic Narrative in Chinese Elite Sport Discourse from Its First Successful Olympic Bid to the Post-Beijing Games Era

Abstract

As a phenomenon exogenous to China, the Olympics have been proactively interpreted in the local context since China’s entry (and subsequent re-entry in 1984) into the Olympic movement. With China’s increasing involvement in promoting three bids to host the Olympic Games, two of which were successful, respectively, in 2001 and 2015, the nature of the discourse of key stakeholders in relation to Chinese elite sport has both reflected and reshaped the meaning of the Games to Chinese elite sport. This paper examines the discursive construction process of the Olympics in the Chinese elite sport system by key stakeholders through analyzing statements of political figures on sport and Olympic phenomena, Chinese elite sport policy documents, and the commentaries of leading Chinese sport academics. The analysis of discourse highlights two main features in the construction of the Games in official accounts during the period under investigation. The development of these two themes reflects the nature of the Chinese Olympic discourse, manifests the political power over the interpretation of the Olympics in Chinese context, and continues to characterize the on-going major themes in Chinese elite sport policy.     

Incorporating Aspects of Information Use into Relevance Feedback

In this paper we look at some of the problems in interacting with best-match retrieval systems. In particular, we examine the areas of interaction, some investigations of the complexity and breadth of interaction and attempts to categorise user's information seeking behaviour. We suggest that one of the difficulties of traditional IR systems in supporting information seeking is the way the information content of documents is represented. We discuss an alternative representation, based on how information is used within documents.     

Transnational Media Management: Western News Organizations’ Web Operations in China

In 2008, China surpassed the United States as the largest Internet market in the world. This study examines how four prominent Western news organizations respond to this new era of Internet publishing. A series of in-depth interviews with senior managers at The Wall Street Journal, Financial Times, Reuters, and The New York Times revealed how these news organizations serve Internet users in China through their Chinese-language Web editions—how they overcome geographic, language, cultural, and political barriers to explore this remote market. These cases demonstrate the viability of different operating models and the challenges and opportunities facing these media organizations as they manage transnational news operations in this seemingly lucrative market.     

Which starting style is faster in sprint running--standing or crouch start?

The purpose of this study was to further understand the biomechanical differences between the standing and crouch starting methods, and to investigate whether one of the starting styles provides better acceleration and proves to be faster. Six university track team sprinters performed 2 x 3 x 50 m trials. Digitised video, photocell timing, and velocity data revealed that during the first steps of the performance the standing start produced higher body centre of mass horizontal velocity than the crouch start. This may be due to the longer distance between the feet in the standing start, which caused longer push-off phases, and the work against gravity in the crouch start. However, this advantage in horizontal velocity disappeared by the 10 m mark, where similar velocities were recorded with both start styles. Further, there was no statistically significant difference between the two starting styles in horizontal velocity at the 25 m mark, nor in the time to reach the 25 m or 50 m mark. Regarding relay running, where athletes need to decide to adopt either a crouch start without starting blocks or a standing start, there seems to be no specific reason for outgoing athletes to use a crouch start, although this area warrants further investigation.