Effect of cadence selection on peak power and time of power production in elite BMX riders; a laboratory based study.

The aims of this study were to analyse the optimal cadence for peak power production and time to peak power in bicycle motocross (BMX) riders. Six male elite BMX riders volunteered for the study. Each rider completed 3 maximal sprints at a cadence of 80, 100, 120 and 140revs·min-1 on a laboratory Schoberer Rad Messtechnik (SRM) cycle ergometer in isokinetic mode. The riders’ mean values for peak power and time of power production in all three tests were recorded. The BMX riders produced peak power (1105±139W) at 100revs·min-1 with lower peak power produced at 80revs:min-1 (1060±69W, (F(2,15)=3.162; p=.266; η2 =0.960), 120revs·min-1 (1077±141W, (F(2,15)=4.348; p=.203; η2 =0.970) and 140revs·min-1 (1046±175W, (F(2,15)=12.350; p=0.077; η2 =0.989). The shortest time to power production was attained at 120revs·min-1 in 2.5±1.07s. Whilst a cadence of 80revs:min-1 (3.5±0.8s, (F(2,15)=2.667; p=.284; η2 =0.800) 100revs:min-1 (3.00±1.13s, (F(2,15)=24.832; p=.039; η2 =0.974) and 140revs:min-1 (3.50±0.88s, (F(2,15)=44.167; p=.006; η2 =0.967)) all recorded a longer time to peak power production. The results indicate that the optimal cadence for producing peak power output and reducing the time to peak power output are attained at comparatively low cadences for sprint cycling events. These findings could potentially inform strength and conditioning training to maximise dynamic force production and enable coaches to select optimal gear ratios

Poutre de grande portée en pierre précontrainte

National audienc

Variability in Laboratory vs. Field Testing of Peak Power, Torque, and Time of Peak Power Production Among Elite Bicycle Motocross Cyclists

The aim of this study was to ascertain the variation in elite male bicycle motocross (BMX) cyclists' peak power, torque, and time of power production during laboratory and field-based testing. Eight elite male BMX riders volunteered for the study, and each rider completed 3 maximal sprints using both a Schoberer Rad Messtechnik (SRM) ergometer in the laboratory and a portable SRM power meter on an Olympic standard indoor BMX track. The results revealed a significantly higher peak power (p <= 0.001, 34 ± 9%) and reduced time of power production (p <= 0.001, 105 ± 24%) in the field tests when compared with laboratory-derived values. Torque was also reported to be lower in the laboratory tests but not to an accepted level of significance (p = 0.182, 6 ± 8%). These results suggest that field-based testing may be a more effective and accurate measure of a BMX rider's peak power, torque, and time of power production

Analyse et controle de l'equation de Duffing et des phenomenes de ferroresonnance dans les lignes electriques. Calcul des bassins d'attraction. Continuation de tores invariants et solutions quasi-periodiques

SIGLEINIST T 76748 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Breeding and genetic health status of dalmatian dog

The aim of this study is to describe the main characteristic and inherited diseases of this Dalmatian breed. One of the most popular breed and most unique by its spotted coat colour. Those breed characteristics have been defined internationally by the FCI and each kennel club must follow those characteristics. This breed is also known for its inherited diseases, such as deafness and Hyperuricosuria which are usually associated with high veterinary cost, sudden death and low average age. They are also prone to eye disorders and skin diseases, but they are less common than the previous two, therefore easier forgotten. Congenital deafness is related to colour genes such as white pieblad one. Over the years, breeders have been selecting Dalmatian for specific colour and spotting according to the standards apply in the kennel clubs. Hyperuricosuria is a defect resulting from inefficient transport of uric acid in both the liver and renal proximal tubules due to a single nucleotide exchange in the gene SLC2AE important for uric acid transport in mammals. The presence of commercial DNA-test and BAER test available for those diseases should make their elimination fast in the next years. Dalmatian Backcross project: This project has been started by Dr.Schaible in 1973, and the goal of was to create low uric acid Dalmatian by crossing a breed dog Dalmatian type known as the Pointer with a Dalmatian and the backcrossing the offspring with a purebreds Dalmatian until he reached the Dalmatian characteristics and low uric acid

Poster Session I, July 14th 2010 — Abstracts Strain in BMX frame through different tests

AbstractThe structural role of the bicycle frame is to transfer the mechanical energy produced by the cyclist at the rear wheel. In bicycle cross (BMX) high loads are applied on the frame, from the pilot, the field and the ground reaction. In BMX, the empirical design and the important power applied on the pedals can lead to the rupture of some tubes. The aim of this study is to equipped a BMX frame with strain gages and to measure the strain of the bicycle frame through tests representative of different actual race conditions: (1) A bar system was designed to simulate the forces applied to the pedals by the pilot in static condition; (2) a pilot applied a maximal isometric force on the pedal with help of handlebars (e.g., Competition start); and (3) a pilot performed one pedaling bout at a cadence of 200 rotations per minute and at power of 550 Watts. During the last two conditions, the tests were realized on an ergo-trainer with two 3D pedals and a SRM.The results obtained through experimentations highlight the strain imbalance in the frame. The conditions as function of time confirm the results obtained in static condition: the seat tube, the down tube and the chain stay have to be strengthened in the area near the bracket. The muscular power output is an important parameter of performance in BMX and the deformation of the frame is proportional to the power developed. To develop a bicycle frame optimized for performance, it is necessary to develop tests that represent the cyclist-frame interaction in actual conditions. This protocol can be useful in order to compare BMX frames and to find the determinant factors to enhance the transfer of mechanical energy from the pedal to the drive train