Ground Reaction Force Differences in the Countermovement Jump in Girls With Different Levels of Performance

Purpose: The aim of this study was to ascertain the biomechanical differences between better and poorer performers of the vertical jump in a homogeneous group of children. Method: Twenty-four girls were divided into low-scoring (LOW; M _age = 6.3 ± 0.8 years) and high-scoring (HIGH; M _age = 6.6 ± 0.8 years) groups based on their performance on the vertical jump. The force-, velocity-, displacement-, and rate of force development (RFD)-time curves of vertical jumps were analyzed to determine the differences between groups. Results: The analysis of the data showed differences in the pattern of the ensemble mean curves of the HIGH and LOW groups, although the majority of the differences occurred during the eccentric contraction phase of the jump. The differences in the HIGH group with respect to the LOW group were: lower force at the beginning of the movement, higher speed and RFD during the eccentric phase, high force at the beginning of the concentric phase, higher velocity during the concentric phase, and a higher position at takeoff. Conclusion: The results showed that the HIGH group achieved a higher jump height than did the LOW group by increasing the effectiveness of the countermovement and achieving a more advantageous position at takeoff.     

Measuring intermittent exercise performance using shuttle running

Abstract

The aim of this study was to include self-paced exercise within a modified Loughborough Intermittent Shuttle Test (LIST-P) in order to quantify key performance variables not possible with prescribed workloads. Sixteen male games players performed two trials of the LIST-P, at least 7 days apart. The LIST-P incorporates 4 × 15-min blocks of “prescribed-pace” activity (participants exercise in time to audible signals) followed by 2 × 15-min blocks of “self-paced” running (no audible signals). Distances covered and mean speeds were monitored during self-paced exercise. Total distance covered (12.54 ± 0.45 km vs. 12.64 ± 0.32 km; P = 0.10) and mean speed (8.37 ± 0.31 km ? h^?1 vs. 8.44 ± 0.22 km ? h^?1; P = 0.10) was similar between trials. Other indices also showed the test to be reliable (Pearson’s correlation = 0.89 and 0.90 (P < 0.01), total distance and mean speed, respectively; intraclass correlation coefficient = 0.88 and 0.88 (P < 0.01); standard error of measurement = ±0.13 km and ±0.09 km ? h^?1; coefficient of variation (CV) = 1.7% and 1.7%; ratio limits of agreement = 1.00 */÷1.03 and 1.01 */÷1.04). Sprint time was also similar between trials (2.60 ± 0.19 s vs. 2.64 ± 0.23 s; P = 0.29). Incorporating self-paced exercise within an established intermittent shuttle running test appears to be a sensitive means of quantifying key performance variables for multiple-sprint sports research.     

Ritual and free‐throw shooting in basketball

The purpose of this study was to determine the nature and effect of certain highly patterned behaviours utilized prior to free‐throw shooting in basketball. Ten female basketball players comprising the varsity squad of Texas Christian University, Fort Worth, Texas, USA served as subjects for this study. Subjects were filmed with a high‐speed camera and monitored for heart rate during the performance of 10 free throws in each of two conditions: ritual and non‐ritual. For the ritual condition, subjects were given unlimited time and freedom of movement prior to each free‐throw attempt. For the non‐ritual condition, subjects were not restricted by time, but were instructed to shoot the ball without utilizing any movements other than those required to project the ball to the goal. Dependent measures were characteristics of behaviours, physiological changes measured by heart rates, mechanical data (speed, height and angle of release), and number of successful attempts. Condition x trials analyses of variance and low standard deviation concerning characteristics of behaviours indicated that the idiosyncratic behaviours prior to free‐throw shooting were rituals of the auto‐communicative type. Results indicated no significant difference between conditions for free‐throw success. However, partial correlation between dependent measures and successful free‐throw attempts indicated that duration of behaviours was most crucial to free‐throw shooting success.     

A Field Test for Upper Body Strength and Endurance

Abstract

Historically, a measure of upper body strength and endurance has been included in fitness test batteries that are typically administered in the school setting. Pull-ups, or some modified form of pull-ups, have been the most popular test item used for the measurement of upper body strength and endurance. Despite the widespread usage of pull-ups, the test has often been criticized because of the large number of zero scores and the subsequent loss of discrimination among ability levels (Jackson & Griffin, 1983). The inability to achieve a score is perceived as failure on the part of the student.     

Comment on a Preliminary Comparison of Front and Back Squat Exercises (Russell & Phillips, 1989)

Abstract

Perception of affordances research in children with developmental disabilities has only examined well practiced skills. Ten toddlers with Down syndrome and 10 with typical development walked across a GAITRite mat, with and without an obstacle. We coded the toddlers' behaviors after 1 and 3 months of walking experience when they encountered the obstacle (avoid, crawl, error, and walk successfully) and calculated gait parameters (step length, width, and velocity). Both groups actively explored their affordances. Despite similar decreases in step length and velocity when approaching the obstacle, toddlers with Down syndrome were more likely to select successful but conservative crawling strategies that minimized balance requirements and reduced risk of falling. Group differences were due to risk management rather than difficulty perceiving affordances.     

Human capital augmentation versus the signaling value of MBA education

Panel data on MBA graduates is used in an attempt to empirically distinguish between human capital and signaling models of education. The existence of employment observations prior to MBA enrollment allows for the control of unobserved ability or selection into MBA programs (through the use of individual fixed effects). In addition, variation in the amount of pre-MBA work experience allows for a test to distinguish between the models. In particular, a predominant signaling view is shown to predict smaller returns to the degree, the more pre-MBA work experience one has (controlling for total experience). Additionally, a unique feature of the data is that respondents were asked to report skills or abilities gained through their schooling, allowing us to determine the extent to which these purported skills are valued in the labor market. The combined evidence suggests that while human capital accumulation may contribute to the returns to an MBA, the majority of the returns is derived from the signaling/screening function of the degree.     

Gender stereotypes among women engineering and technology students in the UK: lessons from career choice narratives

In the UK, women remain under-represented in engineering and technology (E&T). Research has, therefore, investigated barriers and solutions to women's recruitment, retention and progression. Recruitment into the sector may be supported by exploring the career decisions of women and men who have chosen to study E&T. Triangulating quantitative and qualitative data from E&T students at a UK university, this paper examines the gendered nature of career choice narratives. It finds that women often maintain contradictory views; upholding gendered stereotypes about women's suitability for the so-called masculine work, yet also subscribing to ideals that the sector is accessible to all who wish to work in it. This is explained using an individualist framework in which women construct an autonomous sense of self, yet are also shaped by a gendered self. Women's discourse around career choice, therefore, reveals the problematic nature of gender norms for achieving gender equity in E&T.     

Going beyond the book: towards critical reading in statistics teaching

We consider three examples from our own teaching in which much was learned by critically examining examples from books. Even influential and well‐regarded books can have examples where more can be learned with a small amount of additional effort.