Science and cycling: current knowledge and future directions for research

Abstract

In this holistic review of cycling science, the objectives are: (1) to identify the various human and environmental factors that influence cycling power output and velocity; (2) to discuss, with the aid of a schematic model, the often complex interrelationships between these factors; and (3) to suggest future directions for research to help clarify how cycling performance can be optimized, given different race disciplines, environments and riders. Most successful cyclists, irrespective of the race discipline, have a high maximal aerobic power output measured from an incremental test, and an ability to work at relatively high power outputs for long periods. The relationship between these characteristics and inherent physiological factors such as muscle capilliarization and muscle fibre type is complicated by inter-individual differences in selecting cadence for different race conditions. More research is needed on high-class professional riders, since they probably represent the pinnacle of natural selection for, and physiological adaptation to, endurance exercise. Recent advances in mathematical modelling and bicycle-mounted strain gauges, which can measure power directly in races, are starting to help unravel the interrelationships between the various resistive forces on the bicycle (e.g. air and rolling resistance, gravity). Interventions on rider position to optimize aerodynamics should also consider the impact on power output of the rider. All-terrain bicycle (ATB) racing is a neglected discipline in terms of the characterization of power outputs in race conditions and the modelling of the effects of the different design of bicycle frame and components on the magnitude of resistive forces. A direct application of mathematical models of cycling velocity has been in identifying optimal pacing strategies for different race conditions. Such data should, nevertheless, be considered alongside physiological optimization of power output in a race. An even distribution of power output is both physiologically and biophysically optimal for longer ( >4km) time-trials held in conditions of unvarying wind and gradient. For shorter races (e.g. a 1km time-trial), an‘all out’ effort from the start is advised to‘save’ time during the initial phase that contributes most to total race time and to optimize the contribution of kinetic energy to race velocity. From a biophysical standpoint, the optimum pacing strategy for road time-trials may involve increasing power in headwinds and uphill sections and decreasing power in tailwinds and when travelling downhill. More research, using models and direct power measurement, is needed to elucidate fully how much such a pacing strategy might save time in a real race and how much a variable power output can be tolerated by a rider. The cyclist's diet is a multifactorial issue in itself and many researchers have tried to examine aspects of cycling nutrition (e.g. timing, amount, composition) in isolation. Only recently have researchers attempted to analyse interrelationships between dietary factors (e.g. the link between pre-race and in-race dietary effects on performance). The thermal environment is a mediating factor in choice of diet, since there may be competing interests of replacing lost fluid and depleted glycogen during and after a race. Given the prevalence of stage racing in professional cycling, more research into the influence of nutrition on repeated bouts of exercise performance and training is required.     

An evaluation of inertial sensor technology in the discrimination of human gait

Abstract

Inertial sensors may provide the opportunity for broader and more cost effective gait analysis; however some questions remain over their potential use in this capacity. The aim of the study was to determine whether an inertial sensor could discriminate between normal walking, fast walking, and running. A single group crossover design was used to compare acceleration profiles between three gait conditions: normal walking, fast walking, and running. An inertial sensor was placed on the sacrum of 12 participants (6 male, 6 female) who performed 3 trials of each gait condition on both overground and treadmill settings. A significant difference (P < 0.001) in the occurrence of heel strike in the gait cycle was found between running and both walking conditions. No differences were seen between overground and treadmill in any condition or variable. The results indicate that a single sacral mounted inertial sensor can differentiate running from normal walking and fast walking using temporal gait event measures. This study indicates that inertial sensors can differentiate walking from running gait in healthy individuals which may have potential for application in the quantification of physical activity in the health and exercise industry.     

Offensichtlich unsichtbar Die P?dagogisierung des Umgangs mit Wissen im Kontext des lebenslangen Lernens

Der vorliegende Beitrag besch?ftigt sich unter Bezugnahme auf einen systemtheoretischen Kommunikationsbegriff mit der (p?dagogischen) Strukturierung des Lernens Erwachsener. Er geht von der These aus, dass die P?dagogisierung des lernbezogenen Umgangs mit Wissen im Erwachsenenalter unsichtbar (gemacht) wird. Auf der Grundlage eines abgeschlossenen DFG-Projekts werden unterschiedliche Formen p?dagogischer Kommunikation dargestellt und das in ihren Settings, ihrer kommunikativen Verfasstheit und den Mustern ihrer Strukturierung eingelagerte Invisibilisierungspotenzial herausgearbeitet. Vor diesem Hintergrund wird das Konzept des Lebenslangen Lernens als eine entwickelte Form des Umgangs mit dem Paradox der (Un-)Sichtbarkeit p?dagogischer Kommunikation interpretiert. Was diese Institutionalisierungsform des Lernens kennzeichnet, ist somit eine doppelt gegenl?ufige Gleichzeitigkeit von Visibilisierung und Invisibilisierung.     

Using communities of practice to enhance interdisciplinary teaching: lessons from four Australian institutions

We report on the establishment of communities of practice at four Australian institutions and evaluate their effectiveness and durability as a means of building staff and institutional capacity for interdisciplinary teaching. A community of practice approach is a potentially valuable methodology for overcoming dynamics of fragmentation, isolation and competition within universities. The communities we established were anchored by a shared focus on the topic of climate change and they worked collaboratively to build relationships of trust and reciprocity between teachers in a wide range of disciplines. The aim of each community was to improve the teaching of climate change through enabling members to integrate diverse disciplinary perspectives, to teach collaboratively, to promote innovation through exchange and to demonstrate leadership within their institutions. The key factors that made our communities effective and durable are: (1) designation of two leadership roles, activator and facilitator, (2) provision for institutional autonomy in domesticating the model to fit local circumstances and (3) a pragmatic emphasis on opportunities for teaching innovation and leadership within existing administrative structures, teaching programs and workloads. We conclude that suitably designed and resourced communities of practice are a viable means of improving interdisciplinary teaching of complex problems by facilitating both staff development and institutional learning.     

Building a technology foundation for future teachers

It is fitting that the teachers of tomorrow are provided with the correct modeling of technology in their first education class. To separate technology from education is both impossible and foolish. The sooner college students are exposed to the latest forms of technology, the more equipped they will be to integrate these tools into their teaching strategies for the benefit of future learners.     

Reliability,Dimensionality, and Internal Consistency as Defined by Cronbach: Distinct Albeit Related Concepts

This article uses definitions provided by Cronbach in his seminal paper for coefficient α to show the concepts of reliability, dimensionality, and internal consistency are distinct but interrelated. The article begins with a critique of the definition of reliability and then explores mathematical properties of Cronbach's α. Internal consistency and dimensionality are then discussed as defined by Cronbach. Next, functional relationships are given that relate reliability, internal consistency, and dimensionality. The article ends with a demonstration of the utility of these concepts as defined. It is recommended that reliability, internal consistency, and dimensionality each be quantified with separate indices, but that their interrelatedness be recognized. High levels of unidimensionality and internal consistency are not necessary for reliability as measured by α nor, more importantly, for interpretability of test scores.     

Easier Said Than Done: Rejoinder on Sijtsma and on Green and Yang

The main points of Sijtsma and Green and Yang in Educational Measurement: Issues and Practice (34, 4) are that reliability, internal consistency, and unidimensionality are distinct and that Cronbach's alpha may be problematic. Neither of these assertions are at odds with Davenport, Davison, Liou, and Love in the same issue. However, many authors in the testing community mention these terms not only together, but sometimes as if they are synonymous. Moreover, Cronbach's coefficient alpha is very popular as an index of reliability. Thus, articles discussing alpha are not only appropriate, but necessary. Our concerns are the same as formed the genesis of prior (2009) articles by these same authors, Sijtsma and Green and Yang. This rejoinder also makes comments about item parcels when tests are multidimensional and about factor analytic approaches to assessing reliability.