Quantification of brake data acquired with a brake power meter during simulated cross-country mountain bike racing

There is currently a dearth of information describing cycling performance outside of propulsive and physiological variables. The aim of the present study was to utilise a brake power meter to quantify braking during a multi-lap cross-country mountain bike time trial and to determine how braking affects performance. A significant negative association was determined between lap time and brake power (800.8 ± 216.4 W, mean ± SD; r = ?0.446; p < 0.05), while the time spent braking (28.0 ± 6.4 s) was positively associated with lap time (314.3 ± 37.9 s; r = 0.477; p < 0.05). Despite propulsive power decreasing after the first lap (p < 0.05), lap time remained unchanged (p > 0.05) which was attributed to decreased brake work (p < 0.05) and brake time (p < 0.05) in both the front and rear brakes by the final lap. A multiple regression model incorporating braking and propulsion was able to explain more of the variance in lap time (r² = 0.935) than propulsion alone (r² = 0.826). The present study highlights that riders’ braking contributes to mountain bike performance. As riders repeat a cross-country mountain bike track, they are able to change braking, which in turn can counterbalance a reduction in power output. Further research is required to understand braking better.     

Do stiffness and asymmetries predict change of direction performance?

Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R² = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both “large” in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.     

A review of the use of a systematic observation method in coaching research between 1997 and 2016

A systematic observation method has been one of the most popularly employed methods in coaching research. Kahan’s review of this method conducted between 1975 and 1997 highlighted the key trends in this research, and offered methodological guidance for researchers wishing to use this method in their research. The purpose of this review was to provide an update of the use of a systematic observation method in coaching research and assess the extent to which the calls made by Kahan have been addressed. While in some respect this field of study has progressed (i.e., the introduction of qualitative methods), researchers adopting this method have failed to attend to many of the issues Kahan raised. For this method to continue to make a positive contribution towards the coaching research literature, researchers need to more critically reflect on how and why they are employing this method. At present, some of the decisions made by researchers who have conducted work in this area are not justified with a rationale. It is our intention that this review will serve as guidance for researchers and practitioners, and editors and reviewers of journals when attempting to assess the quality of this type of work.     

How capital operates and where the world and China are going: a conversation between David Harvey and Paik Nak-chung

The conversation first takes up the theme of David Harvey’s public lecture in Seoul, “Realization Crises and the Transformation of Everyday Life.” Harvey stresses that the relative neglect of Volume 2 of Marx’s Capital has prevented scholars and activists from paying due attention to the crucial importance of value realization for the reproduction of capital. The discussion then moves on to the city as both a site of production and of liberation struggles, a topic so far largely neglected in the Marxist tradition. Regarding the neoliberal phase of capitalism, Harvey calls it a “new imperialism” characterized by “accumulation by dispossession” as its guiding principle. Paik agrees to that distinguishing feature as compared with the immediately preceding phase where creation and appropriation of surplus value were more prominent, but suggests that “accumulation by dispossession” may have been an essential attribute of capitalism from the sixteenth century on. After ranging over a variety of topics, the conversation looks at the latest developments in the Chinese economy, how they may illustrate Harvey’s notion of capital’s “spatial fix,” and what other potentialities may yet be found in China’s diverse and complex reality.     

Social maladjustment and emotional disturbance: Problems and positions I

Several controversies continue to surround the differentiation between the socially maladjusted (SM) and seriously emotionally disturbed (SED). Central to the controversy is the interpretation of social maladjustment. At one extreme, some restrict the definition of SM to include (a) the socialized aggressive and (b) adjudicated delinquents. At the other extreme, SM is construed broadly and includes (a) Conduct Disorder (group type, solitary aggressive, and undifferentiated), (b) Oppositional Defiant Disorder, and (c) antisocial personality. An intermediate position presented herein argues for the inclusion of the socialized aggressive and unsocialized aggressive under the rubric of SM. Given that those in the anxious-withdrawn-dysphoric group are viewed as both SM and SED, they should be eligible for special education services assuming adverse educational impact is evident.     

Socioeconomic bias in special education placement decisions

This study analyzed the planning and placement decisions of the Educational Placement and Planning Committees for 973 students in the State of Michigan. An attempt was made to determine if evidence suggesting a socioeconomic bias in placement existed. Data included students from five categories: learning disabled (N = 323), educable mentally impaired (N = 163), emotionally impaired (N = 83), otherwise impaired (N = 70), and nonimpaired (N = 334). No statistically significant differences that would indicate an SES bias were found. However, other factors (sex, age, intelligence, location of district) may contribute substantially to special education placement. Significant agreement was found between school psychologists and teacher consultants with respect to placement decisions. Results are discussed in terms of the apparent absence of any socioeconomic bias in team decision making.     

The dilemma of diagnosis in learning disabilities: Problems and potential directions

Current procedures for diagnosing perceptual and language deficits in the face of academic underachievement have resulted in a categorical expression—learning disabilities. In this paper, the contention is offered that learning disabilities so ascertained constitutes, at best, an expression, not a diagnosable entity. Current definitions may be incapable of describing a meaningful population for research or providing data that are useful for instructional management or placement. Two features are described that could become central in a diagnosable entity termed a learning disability.