Effect of endpoint conditions on position and velocity near impact in tennis

Smoothing to obtain accurate position and velocity data near impacts in sport biomechanics studies is complicated by the accelerations of impact, endpoint effects and the smoothing technique used. Wrist goniometric data with two levels of random noise added were used to examine three endpoint modelling conditions for obtaining accurate position and velocity data at impact in the tennis forehand. The common approach of smoothing through impact created distortions of the position signal up to 100 ms before impact and resulted in consistent underestimations (-3.2%) of wrist angle and angular velocity (-67.9%) at impact. New linear and polynomial extrapolation conditions smoothed with all techniques provided lower root mean squared errors than the smoothing-through-impact condition, with discrete wrist positions at impact within 1.1% of the criterion data. Both the new linear and polynomial conditions can be used to make more accurate angular position and velocity estimates for tennis impacts, whereas the smoothing-through-impact condition creates spurious decreases in speed before impact that in the past have been assumed to be aspects of skilful movement.     

Tennis

This study investigated the effect of the larger diameter (Type 3) tennis ball on performance and muscle activation in the serve. Sixteen male advanced tennis players performed serves using regular size and Type 3 tennis balls. Ball speed, surface electromyography, and serve accuracy were measured. There were no significant differences in mean initial serve speeds between balls, but accuracy was significantly greater (19.3%) with the Type 3 ball than with the regular ball. A consistent temporal sequence of muscle activation and significant differences in mean activation of different muscles were observed. However, ball type had no effect on mean arm muscle activation. These data, combined with a previous study, suggest that play with the larger ball is not likely to increase the risk of overuse injury, but serving accuracy may increase compared to play with the regular ball.     

Student factors related to learning in biomechanics

The aim of this study was to identify the student behaviours and characteristics that are related to learning biomechanical concepts. The Biomechanics Concept Inventory (BCI) was given to 53 kinesiology majors before and after an introductory biomechanics class together with a survey of student behaviours to determine factors that assisted in learning. Analysis of scores from 49 students showed significant (P < 0.001) improvement following instruction. Variables that significantly (P < 0.05) and uniquely correlated with improvement were grade point average (r = 0.46) and student interest in biomechanics (r = 0.41). Thirty-one percent of the variance in learning could be accounted for by these two variables, with no distinctive associations with student behaviours like course reading, hours studying, and credits earned in maths and physics. However, grade point average was significantly correlated with several student behaviour variables. Consequently, student learning of biomechanical concepts is likely a complex phenomenon with individual learning related to variables that interact with student interest and overall academic ability.     

Does student learning style affect performance on different formats of biomechanics examinations?

Students' learning style preferences have been widely adapted into teaching and learning environments. The purpose of this study was to investigate the relationship between self-reported and assessed learning style preferences (visual, auditory, reading/writing, kinesthetic: VARK) on performance in different types of multiple-choice examinations (T1: text only format and T2: visual format) given in an introductory biomechanics class. Students who enrolled in three biomechanics classes at a state university were recruited to participate in the study. Ninety students (47 males and 43 females) completed a learning style survey and two types of examinations. Results showed that approximately half of the students were assessed and self-reported as kinesthetic for their preferred learning style. There was no significant difference in test performance between students who preferred visual and reading/writing learning styles (self-reported and assessed). These students demonstrated similar learning and comprehension of biomechanical concepts regardless of whether the test material was presented in their preferred sensory mode or not. Interestingly, female students' perceptions of their learning style preference may have a positive effect on the test results when the test is presented in their preferred format.     

Intimacy of Friendship, Interpersonal Competence, and Adjustment during Preadolescence and Adolescence

This study examined the hypotheses that (a) intimacy of friendship is more integral to socioemotional adjustment during adolescence than preadolescence, and (b) that competence in close relationship skills is more important during adolescence than preadolescence. Subjects were 102 10-13-year-old preadolescents and 70 13-16-year-old adolescents. Self- and friend ratings of friendship intimacy were gathered using a 2-step procedure ensuring that students rated only reciprocated friendships. Self- and friend ratings of close relationship competence were gathered using the newly developed Adolescent Interpersonal Competence Questionnaire. Intimacy of friendship was consistently and moderately correlated with adjustment and competence among adolescents but less consistently related among preadolescents. Significant age differences in coefficients were predominantly found for correlates of self-reported rather than friend-reported intimacy. Overall, the findings support the view that the ability to establish close, intimate friendships becomes increasingly important during early adolescence.     

Prominent Messages in Television Drama Switched at Birth Promote Attitude Change Toward Deafness

The study at hand employed a pre- versus posttest experimental design to test the effects of television drama Switched at Birth on viewers’ attitudes toward deafness. This program tells the story of two teenage girls (one of whom is deaf) and their struggles to relate to their peers and families after discovering they were switched as newborns. Two hundred eleven female adults completed pre- and postexposure measures utilizing Cooper, Rose, and Mason's (2004 Cooper , A. , Rose , J. , &; Mason , O. ( 2004 ). Measuring the attitudes of human service professionals toward deafness . American Annals of the Deaf , 148 , 385 – 389 .[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) Attitudes to Deafness measure, the items of which were categorized according to thematic dimensions. After exposure to one of three episodes, viewers’ attitudes toward deafness significantly improved overall, although significant differences in attitude changes varied by episodes and dimensions. The three thematic dimensions that were most strongly represented in the program (social interaction, deafness as a handicap, and language issues) appeared to show the strongest attitude change. Positive attitude changes were observed on social interaction and deafness as handicap dimensions, which was consistent with program content depicting positive deaf-hearing friendships and capable deaf characters. However, attitudes on the language issues dimension showed a negative shift, possibly due to the way that deaf characters communicated with hearing characters onscreen.     

Superintendents of American residential schools for the deaf: a profile

Data on selected characteristics of superintendents of American residential schools for the Deaf were gathered in a 1999 survey. The resulting profile of superintendents of residential schools was then compared with a profile of superintendents of public elementary and secondary schools that had been compiled in 1992 by the American Association of School Administrators. The study population consisted of the lead administrators of the 72 residential schools for the Deaf in operation in the United States at the time of the survey. One particularly note-worthy finding was that these superintendents reported the same beliefs about their essential responsibilities that had been reported by superintendents of public elementary and secondary schools. The greatest disparity between the two groups of superintendents was in how they characterized their relationships with their governing boards: Generally, the residential school superintendents reported relationships that were less formal. The study, apparently the first attempt to profile superintendents of American residential schools for the Deaf, establishes a baseline for future studies of this kind.