The influence of wearing ski-boots with different rigidity characteristics on postural control

Abstract

External supports that reduce ankle joint mobility such as ski-boots can impair postural control of healthy participants. Although this disruptive effect has been attributed to the rigidity of the external supports, the results remained controversial and no study has been conducted in order to evaluate the influence of ski-boots rigidity. Hence, the question about the influence of ankle support rigidity on postural control remains open. This study was therefore undertaken in order to investigate the effect of ski-boots rigidity on postural control. Ten healthy active participants were recruited. The wearing of soft and rigid ski-boots was compared to barefoot while standing on a seesaw generating mediolateral and anteroposterior instability. Centre of pressure displacements were sampled with a force platform. The surface electromyographic activity of the main muscles from the leg, thigh and trunk was recorded. A motion analysis system was also used to calculate the ankle, knee and hip angles. The results did not reveal any negative influence of ski-boot rigidity on postural control but rather suggest a less active postural control with the rigid ski-boots which offered a higher mechanical contribution.     

Effectiveness of school‐based universal social,emotional, and behavioral programs: Do they enhance students’ development in the area of skill,behavior, and adjustment?

To answer the question of whether teaching social and emotional skills to foster social–emotional development can help schools extend their role beyond the transfer of knowledge, the authors conducted a meta‐analytical review of 75 recently published studies that reported the effects of universal, school‐based social, emotional, and/or behavioral (SEB) programs. The analyzed interventions had a variety of intended outcomes, but the increase in social skills and decrease in antisocial behavior were most often reported. Although considerable differences in efficacy exist, the analysis demonstrated that overall beneficial effects on all seven major categories of outcomes occurred: social skills, antisocial behavior, substance abuse, positive self‐image, academic achievement, mental health, and prosocial behavior. Generally, immediate effects were stronger than delayed effects, with the exception of substance abuse, which showed a sleeper effect. Limitations of the analysis and moderators of the effectiveness of SEB programs in schools are discussed in the final section of the article.     

PART III: KINANTHROPOMETRY

Whole-body bone mineral density and bone mineral mass in young adult rugby union players.     

Unstable footwear as a speed-dependent noise-based training gear to exercise inverted pendulum motion during walking

ABSTRACT

Previous research on unstable footwear has suggested that it may induce mechanical noise during walking. The purpose of this study was to explore whether unstable footwear could be considered as a noise-based training gear to exercise body center of mass (CoM) motion during walking. Ground reaction forces were collected among 24 healthy young women walking at speeds between 3 and 6 km h^?1 with control running shoes and unstable rocker-bottom shoes. The external mechanical work, the recovery of mechanical energy of the CoM during and within the step cycles, and the phase shift between potential and kinetic energy curves of the CoM were computed. Our findings support the idea that unstable rocker-bottom footwear could serve as a speed-dependent noise-based training gear to exercise CoM motion during walking. At slow speed, it acts as a stochastic resonance or facilitator that reduces external mechanical work; whereas at brisk speed it acts as a constraint that increases external mechanical work and could mimic a downhill slope.     

From Marin County's Seventies Clunker to the Durango World Championship 1990: A History of Mountain Biking in the USA

Between the 1970s, during which several enthusiastic cyclists rode off-road, and the 1990s, during which the first Union Cycliste Internationale World Championship took place in Durango (Colorado), different steps contributed to the success of mountain bike in the US. Inventions took place throughout the period from Gary Fisher's mechanical improvements in 1975 to Joe Breeze's first specialized frames made in 1977. In the same fashion, the ‘Stumpjumper’ was sold on a large scale in 1982, making it the first industrially-produced mountain bike, which led to a new stage in terms of commercialization. The mountain bike opened a new market in the cycling industry and certainly became more financially accessible to a large number of people. This sport, which began in the US, became a worldwide outdoor sport in the last decade of the twentieth century when the Olympics welcomed it with open arms at the Atlanta Olympic Games.     

Execution time, kinetics, and kinematics of the mae-geri kick: comparison of national and international standard karate athletes

Little is known of the performance characteristics of the shotokan karate mae-geri kick. The aim of this study was to compare the execution time, the lower limb kinetics and kinematics, and their respective repeatability in the mae-geri kick of karate athletes of two different standards. Seventeen adult black belt karate competitors (9 national and 8 international athletes) performed six kicks with their dominant lower limb on a striking surface, combining maximum force impact and velocity. Execution time of movement and lower limb kinematics were recorded with a high-speed camera. Maximum force at impact and the forces exerted on the ground were measured using three force plates. The duration of the kick was significantly shorter for international than for national standard athletes. However, no significant difference in the maximum impact force of the kick was observed between the two groups. In addition, significant kinematic differences were observed between the groups, with two angles of motion and one velocity peak occurring sooner in the kick movement for the international athletes, specifically for the knee joint. International athletes also performed the kick with a significantly higher repeatability for duration and kinematics, specifically during the pre-loading phase that precedes the attack phase. We conclude that the duration of the kick and repeatability of lower limb kinematics could be useful in selecting top-level karate athletes and monitoring their training status.     

Chemical Engineering and Environmental Engineering Education in Hungary

Engineering education has more than 200 years of tradition in Hungary. Chemical engineers are trained at the Technical University of Budapest (TUB) and at the University of Veszprém. The curriculum of the TUB chemical engineering education is given. Undergraduate environmental engineering education is offered at the University of Miskolc, at the Janus Pannonius University in Pécs and at the University of Veszprém. Curricula of the latter two are given. The TUB has several environmental specialization opportunities for engineering students, but at present no separate undergraduate environmental engineering education is offered. Such a curriculum is now under preparation and will be introduced in 1998. Several technical colleges also offer environmental engineering education, where the duration of the training is 3 years. Postgraduate education is a very suitable form to add environmental knowledge to the existing engineering knowledge of graduate engineers. The TUB and the universities in Miskolc and Veszprém are all very active in this field.     

The Development and Psychometric Evaluation of a Multidimensional Measurement Instrument of Professional Expertise

The aim of the present study was to determine the nature of the knowledge and skills related to professional expertise, and to develop means by which such expertise may be individually measured. An instrument was developed consisting of five different scales (with contents ranging from 12 to 19 items each), each reflecting one of five dimensions: knowledge, meta-cognitive knowledge, skills, social recognition, growth and flexibility. Participants were two different, but relevant, groups of raters: individual employees (N = 558) and their immediate supervisors (N = 454). The item-sets for both groups are nominally identical, except that the wording was adapted when necessary to suit one group or the other. The reliabilities of the developed scales were high with Cronbach's alpha ranging from 0.83 to 0.94, for both the self-ratings and the supervisor ratings. All five scales are homogeneous and distinctive as corroborated by Multitrait-Multimethod and LISREL analyses. Background and construction of the instrument are discussed at length and the instrument is appended in two versions: the original Dutch questionnaire and an English version.