Kinematic differences in upper limb joints between flat and topspin forehand drives in competitive male tennis players

Abstract

The topspin tennis forehand drive has become a feature of modern game; yet, as compared to the serve, there has been little research analysing its kinematics. This is surprising given that there is considerably more variation in the execution of the topspin forehand. Our study is the first to examine the amplitude of upper limb joint rotations that produce topspin in the forehand drives of 14 male competitive tennis players using video-based motion analysis. Humerothoracic abduction (-)/adduction (+), extension (-) /flexion (+), and external (-)/internal (+) rotation, elbow extension (-) /flexion (+) and forearm supination (-)/pronation (+), wrist extension (-)/flexion (+) and ulnar (-)/radial (-) deviation were computed. Our findings revealed that the generation of topspin demanded more humeral extension and forearm pronation but less humeral internal rotation angular displacement during the forwardswing. The follow-through phase of the topspin shot was characterised by greater humeral internal rotation and forearm pronation, and reduced humeral horizontal adduction when compared to the flat shot. This study provides practitioners with a better understanding of the upper limb kinematics associated with the topspin tennis forehand drive production to help guide skill acquisition interventions and physical training.     

Teacher locus of control and classroom climate: A cross-lagged correlational study

The Locus of Control Scale for Teachers was given to 13 middle school teachers, and the Origin-Climate Questionnaire was given to 78 of their students. Results indicated a moderate relationship between teachers' locus of control and students' perception of classroom climate. The difference between the cross-lagged correlations suggested that teachers' locus of control has a causal impact on classroom climate.     

The myths about e‐learning in higher education

Proponents have marketed e‐learning by focusing on its adoption as the right thing to do while disregarding, among other things, the concerns of the potential users, the adverse effects on users and the existing research on the use of e‐learning or related innovations. In this paper, the e‐learning‐adoption proponents are referred to as the technopositivists. It is argued that most of the technopositivists in the higher education context are driven by a personal agenda, with the aim of propagating a technopositivist ideology to stakeholders. The technopositivist ideology is defined as a ‘compulsive enthusiasm’ about e‐learning in higher education that is being created, propagated and channelled repeatedly by the people who are set to gain without giving the educators the time and opportunity to explore the dangers and rewards of e‐learning on teaching and learning. Ten myths on e‐learning that the technopositivists have used are presented with the aim of initiating effective and constructive dialogue, rather than merely criticising the efforts being made.     

Cross-Cultural Concepts of Adolescence in Europe,the United States and Japan

In the twentieth century, in Europe and North America, the origin and development of the concept of adolescence owes much to the growth of universal education. However, in the latter years of the present century the countries of Europe and North America began to experience relative economic decline and, at the same time, develop growing respect for the educational achievements of the countries of the Pacific Rim. This paper seeks to examine models of adolescence more closely both in the countries of the first industrial revolution and in the country that leads the world in academic achievement – Japan.     

Muscle activation,blood lactate,and perceived exertion responses to changing resistance training programming variables

Ratings of perceived exertion (RPE: 0–10) during resistance training with varying programming demands were examined. Blood lactate (BLa) and muscle activation (using surface electromyography: EMG) were measured as potential mediators of RPE responses. Participants performed three sets of single arm (preferred side) bicep curls at 70% of 1 repetition maximum over 4 trials: Trial (A) 3 sets?×?8 repetitions?×?120?s recovery between sets; (B) 3 sets?×?8 repetitions?×?240?s recovery; (C) 3 sets?×?maximum number of repetitions (MNR)?×?120?s recovery; (D) 3 sets?×?MNR?×?240?s recovery. Overall body (RPE-O) and active muscle (RPE-AM) perceptual responses were assessed following each set in each trial. Biceps brachii and brachioradialis muscle EMG was measured during each set for each trial. RPE-O and RPE-AM were not different between Trial A (3.5?±?1 and 6?±?1, respectively) and Trial B (3.5?±?1 and 5.5?±?1, respectively) (p?p?相似文献   

EVALUATION OF TEACHING

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