The relationship between shoulder alignment and elbow joint angle in cricket fast-medium bowlers

The aim of this study was to examine the relationship between shoulder alignment and elbow angle during the delivery action of fast-medium bowlers. The elbow and upper trunk alignment were recorded for 13 high-performance bowlers (mean age 20 years) using a 12-camera Vicon motion analysis system operating at 250 Hz. The three highest velocity trials for "good" and "short" length deliveries were analysed. Results showed that bowlers with a more front-on shoulder alignment at back-foot impact and when the upper arm was horizontal to the ground experienced a significantly greater elbow flexion--extension range when compared with those who had a more side-on orientation at the same point in the delivery action. Bowlers with greater shoulder counter-rotation also recorded higher elbow flexion and subsequently extension during the period from upper arm horizontal to ball release. Shoulder alignment and elbow angles were similar for "short" and "good" length deliveries. It was concluded that bowlers with a more front-on shoulder orientation at back-foot impact demonstrated a higher elbow extension from upper arm horizontal to ball release and are therefore more likely to infringe International Cricket Council elbow tolerance levels, compared with those who adopt a more side-on shoulder orientation at back-foot impact.     

Effect of chainring ovality on joint power during cycling at different workloads and cadences

Non-circular chainrings theoretically enhance cycling performance by increasing effective chainring diameter and varying crank velocity, but research has failed to consistently reproduce the benefits in cycling trials. The aim of this study was (1) to investigate the effect of different chainring shapes on sagittal knee joint moment and sagittal lower limb joint powers and (2) to investigate whether alterations are affected by cadence and workload. Fourteen elite cyclists cycled in six conditions (70, 90 and 110 rpm, each at 180 and 300 W), for 2 min each, using three chainrings of different ovalities (1.0–1.215). Kinematic data and pedal forces were collected. For most conditions, only the chainring with the highest ovality (1.215) was characterised by smaller sagittal knee joint moments, smaller relative sagittal knee joint power contribution and larger relative sagittal hip joint power contribution, which suggests a change from maximising efficiency to maximising power production. Effect sizes increased with higher cadences, but not with higher workload. This study has application for athletes, clinicians and sports equipment industry as a non-circular chainring can change joint-specific power generation and decrease knee joint moment, but certain ovality seems to be necessary to provoke this effect.     

Cognitive behavioural strategies and anxiety in elite orienteers

The primary purpose of this exploratory field study was to examine the use of cognitive behavioural strategies by highly skilled orienteers prior to and during competition. A secondary purpose of the study was to investigate whether differences in the level of qualification in orienteering is related to state anxiety. The subjects were divided into three classes with respect to their international and national records. The first two classes (A and B) were composed of international and national level athletes. The third class (C) included orienteers with unknown international records. Examination of the use of behavioural cognitive strategies during competition indicated that all orienteers reported a moderate use of mental imagery, above moderate use of inner talk and a focus of attention on present action rather than past or future. The other major findings were that prior to competition, superior orienteers reported use of higher self‐efficacy, more positive outcome expectations and more task demand orientation than their less successful counterparts. Top orienteers coped more successfully with pre‐competition anxiety by lowering their anxiety to a more moderate level prior to the actual performance.     

Dynamics of the martial arts high front kick

Fast unloaded movements (i.e. striking, throwing and kicking) are typically performed in a proximo‐distal sequence, where initially high proximal segments accelerate while distal segments lag behind, after which proximal segments decelerate while distal segments accelerate. The aims of this study were to examine whether proximal segment deceleration is performed actively by antagonist muscles or is a passive consequence of distal segment movement, and whether distal segment acceleration is enhanced by proximal segment deceleration. Seventeen skilled taekwon‐do practitioners were filmed using a high‐speed camera while performing a high front kick. During kicking, EMG recordings were obtained from five major lower extremity muscles. Based on the kinematic data, inverse dynamics computations were performed yielding muscle moments and motion‐dependent moments. The results indicated that thigh deceleration was caused by motion‐dependent moments arising from lower leg motion and not by active deceleration. This was supported by the EMG recordings. Lower leg acceleration was caused partly by a knee extensor muscle moment and partly by a motion‐dependent moment arising from thigh angular velocity. Thus, lower leg acceleration was not enhanced by thigh deceleration. On the contrary, thigh deceleration, although not desirable, is unavoidable because of lower leg acceleration.     

Texts

Made in America: Immigrant Students in Our Public Schools. Laurie Olsen, New York: The New Press, 1997, 276 pages, $25.00 (hardcover), ISBN 1–5658–4400–9, and $14.95 (softcover), ISBN 1–5658–4471–8.

The Power of Their Ideas: Lessons for America From a Small School in Harlem. Deborah Meier, Boston: Beacon Press, 1995, 190 pages, $12.00 (softcover). ISBN 0–8070–3111–9.

Yesterday, Today & Tomorrow: Meeting the Challenge of Our Multicultural America & Beyond. Paul D. Christiansen and Michelle Young, San Francisco: Gaddo Gap Press, 1996, 376 pages, $29.95 (softcover). ISBN 1–8801–9218–7.     

English phonological awareness in bilinguals: a cross‐linguistic study of Tamil,Malay and Chinese English‐language learners

To test the lexical restructuring hypothesis among bilingual English‐language learners, English phonological awareness (PA), English vocabulary and ethnic language vocabulary (Mandarin Chinese, Malay or Tamil) were assessed among 284 kindergarteners (168 Chinese, 71 Malays and 45 Tamils) in Singapore. A multi‐level regression analysis showed that English vocabulary, in interaction with mother's education, statistically significantly predicted Singaporean children's PA; ethnic language vocabulary did not. Thus, the present study supports the lexical restructuring hypothesis that growth in vocabulary changes how lexical items are stored, leading to the development of PA. Home language practices, as represented by mother's education, may also enhance children's PA after a threshold of English vocabulary is reached. In addition, specific ethnic language (Chinese, Malay or Tamil) was a statistically significant predictor of PA, suggesting that orthographic depth as well as syllabic complexity of a bilingual's other language may influence their development of English PA.     

When does an opportunity become an opportunity? Unpacking classroom practice through the lens of ecological psychology

Drawing on ecological psychology, this paper considers how student engagement is an accomplishment of the classroom system. Specifically, this paper presents an analysis of two teachers and their students who were using a project-based unit in their mathematics classes. The two teachers used identical curricular materials, but had dramatically different personal histories of teaching and different instructional practices. Our goal is to investigate the role of the teacher in supporting student engagement by considering the kinds of opportunities to learn that were presented by the teacher, and the relationship between those opportunities to learn and the ways their students engaged. Pragmatically, this paper contributes to our understanding of how teachers’ framing of activity significantly impacts the ways that students are likely to engage tasks. Theoretically, this paper highlights the interactional nature of learning, with the goal of clarifying why learning is not simply an individual accomplishment.