Comparación de diferentes métodos de ajuste de la bicicleta en ciclistas entrenados: influencia de factores biomecánicos y energéticos = Comparison of different methods to adjust the bicycle in trained cyclists: influence of biomechanical and energetic factors

Abstract

The performance in road cycling depends on several factors such as physiology (VO 2Max , intensity, pedalling efficiency, fatigue, age, gender), environment (air-wind, atmospheric pressure, temperature, relative humidity, and the slope of the terrain) psychology, (self-talk, focus and teleoanticipation), training (strength, endurance, altitude training, heat acclimation, technique and tapering), nutrition (competitive nutritional strategy) and biomechanics (resistive forces, propulsive forces, pedalling kinematics and bicycle setup). Although, the actual influence of some of these factors is still unknown, some studies have demonstrated the influence of proper bicycle configuration on aerodynamic drag, muscular coordinative pattern, pedal forces profile and, consequently, on energy expenditure. Saddle height and crank length are key factors in the lower limb kinetic change thus can contribute significantly on pedalling efficiency. There is some controversy in the specific cycling literature concerning the optimal method to adjust saddle height. Anthropometric references (e.g. 106-109% of the inseam length) laid down on 70's or 80's (when toe-clip were mainly used) are still used today. The static goniometric method (cyclists should achieve a knee angle of 25-35º with the pedal located at the bottom dead centre) has been recommended in order to improve the anthropometric one. Furthermore, it has become increasingly frequent in recent years to use the dynamic goniometric method (2d analysis during pedalling), thanks to the introduction of new technologies. In this method, cyclists should achieve a knee flexion angle of 30-40º during pedalling) with the aim of optimizing muscle length and the lever arm, which vary with saddle height changes. In high-level cycling, small details can determine the final result. Moreover, at that level, the bicycle setup is difficult to handle because the narrow range for possible modifications. To date, some studies have demonstrated the effect of Abstract wide changes in bicycle configuration on pedalling efficiency. However, the influence of small changes in factors such as saddle height or crank length remains unclear. The present Thesis would try to explain these issues by the following aims, addressed in four chapters: 1.-Verify if the anthropometric method (adjusting saddle height from 106% to 109% of the inseam length) ensure an optimal knee angle while pedalling (dynamic method), 2-Compare the static and dynamic goniometric methods in order to adjust the saddle height and analyse if the differences between methods are dependent of the relative saddle height, 3evaluate the acute effects of small changes in saddle height on gross efficiency and lower-limb kinematics in well-trained cyclists, 4-analyse the acute effects of small changes in crank length on the energy cost of cycling and pedalling technique (kinetic and kinematic profiles) during submaximal pedalling Twenty three high-level male cyclists of the same team participated in the first study. Results support the view tha...