Are gait characteristics and ground reaction forces related to energy cost of running in elite Kenyan runners?

The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h^?1 and 20 km ·h^?1). VO₂ and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg^?1· km^?1 at 12 km· h^?1 and 184.8 ± 9.9 ml· kg^?1· km^?1 at 20 km· h^?1, which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg^?1·km^?1 and 0.93 ± 0.07 kcal· kg^?1· km^?1. We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h^?1. However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.     

Comment on ‘Ventilation and blood lactate increase exponentially during incremental exercise’ : A reply

Oar force and oar angle data resulting from a 6‐min maximal rowing ergometer test undertaken by novice (n = 9), good (n ‐ 23) and national (n = 9) level male rowers, were used to identify biomechanical performance variables which accurately discriminated between rowers of differing ability levels. The variables included two work capacity measures, mean propulsive power output per kilogram of body mass (W kg^‐1) and propulsive work consistency (%), and two skill variables, stroke‐to‐stroke consistency (%) and stroke smoothness (%). Discriminant function analysis indicated the presence of two functions, both of which clearly indicated the importance of mean propulsive power output per kilogram of body mass as a discriminating variable. Function 2 gave greater weight to stroke‐to‐stroke consistency and stroke smoothness than function 1; however, function 1 was the most powerful discriminator. Classification procedures were used to predict the ability level to which a rower most likely belonged and involved defining the ‘distance’ between each rower and each ability level centroid, with the rower being classified into the ‘nearest’ ability level. These procedures indicated that 100% of the elite, 73.9% of the good, 88.9% of the novice and 82.9% of all rowers were correctly classified into their respective skill levels. Stepwise discriminant analysis included the variables in the following order: mean propulsive power output per kilogram of body mass, stroke‐to‐stroke consistency, stroke smoothness and propulsive work consistency (P < 0.001). The results of this study indicate that biomechanical performance variables related to rowing capacity and skill may be identified and used to discriminate accurately between rowers of differing skill levels, and that, of these variables, propulsive work consistency is the least effective discriminator.     

Positive functions of emotions in achievement sports

This article presents the results of two research projects on the emotions of men engaged in achievement outdoor sports. The conditions were analyzed under which emotions carry out positive functions. The question strikes us as a fundamental one, because it is of crucial importance when it comes to increasing sportspeople's success. The theoretical framework applied was that of microfunctionalism. The method, of a qualitative nature, was based on in-depth interviews, each lasting between 1.5 and 2 hr with a total of 14 sportspersons. The results show that in order for emotions to fulfill positive functions, three conditions must be met: (a) existence of passion, which, with its dialectical character of pleasure and suffering underlies all the other emotions and acts as a motor that pushes the sportsperson forward, despite all the contretemps he might meet on the way; (b) intense emotion work, which may be conducted only if accompanied by knowledge and experience of the natural environment acquired over the years; and (c) conciliation between emotion work and the feeling rules characteristic of each sport subculture. For those individuals who pursue achievement in outdoor sports, these results will provide more concrete indications regarding how to carry out the emotional preparation required for these sports.     

A fluid dynamic investigation of the Big Blade and Macon oar blade designs in rowing propulsion

The purpose of this investigation was to examine the fluid dynamic characteristics of the two most commonly used oar blades: the Big Blade and the Macon. Scaled models of each blade, as well as a flat Big Blade, were tested in a water flume using a quasi-static method similar to that used in swimming and kayaking research. Measurement of the normal and tangential blade forces enabled lift and drag forces generated by the oar blades to be calculated over the full range of sweep angles observed during a rowing stroke. Lift and drag force coefficients were then calculated and compared between blades. The results showed that the Big Blade and Macon oar blades exhibited very similar characteristics. Hydraulic blade efficiency was not therefore found to be the reason for claims that the Big Blade could elicit a 2% improvement in performance over the Macon. The Big Blade was also shown to have similar characteristics to the flat plate when the angle of attack was below 90 degrees , despite significant increases in the lift coefficient when the angle of attack increased above 90 degrees . This result suggests that the Big Blade design may not be completely optimized over the whole stroke.     

Students’ Perceptions of Coursework in the GCSE: the effects of gender and levels of attainment

Summary Coursework is an integral part of the GCSE framework, valued for its motivational qualities and its curricular validity. It is a common perception, widely reported in the national press and educational media, that coursework can be held at least partly accountable for differential performances at GCSE; coursework, it is argued, advantages girls. This article reports on an analysis of data arising from a project which offered an opportunity to study current and post-GCSE students’ perceptions of coursework. The outcomes indicate that, when categorised by their relative levels of attainment, girls’ and boys’ perceptions show limited evidence of homogeneity. In other words, to suggest that girls’ and boys’ perceptions of coursework are a function of gender is a gross over-simplification. Other factors are at play and further, more specific and tailored research is essential if we are to understand how best to optimise the benefits that are claimed for coursework.     

The story of large electron positron collider

In this first part of the article on LEP detector, we have described in brief the standard model for the fundamental constituents of matter. We have also described the experimental supports for the electroweak theory and quantum chromodynamics, which are the two pillars of the standard model. In the next part of the article, we will focus on the LEP detector and the measurements that have been carried out with it.