Manioc : Portail | resultats 1 - 20 pour la recherche: arm length

Observations and advices for the improvement of the manufacture of muscovado sugar and rum. Part 2
Auteur(s) : Higgins, Bryan (1737?-1820)
Année de publication :

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Narrative of a five years' expedition against the revolted negroes of Surinam in Guiana, on the wild coast of South America from the year 1772 to 1777, elucidating the history of that country and describing its productions... with an account of the Indians of Guiana and negroes of Guinea... Tome 2
Auteur(s) : Stedman, John Gabriel (1744-1797)
Année de publication :

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Speeches of Henry Lord Brougham, upon questions relating to Publics Rights, Duties, and Interests
Auteur(s) : Brougham, Henry (1778-1868)
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Candid and impartial considerations on the nature of the sugar trade : the comparative importance of the British and French Islands in the West-Indies : with the value and consequence of St. Lucia and Granada, truly stated. Illustrated with copper-plates
Auteur(s) : Campbell, John (1708-1775)
Année de publication :

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Reports from committees : eighteen volumes. Sugar and coffee planting. Session 18 november 1847 - 5 september 1848, Part. 4
Auteur(s) : Grande Bretagne. House of commons. Library
Année de publication :

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Enhancing cycling performance using an eccentric chainring
Auteur(s) : Hue, Olivier Galy, Olivier Hertogh, Claude Casties, Jean-François Prefaut, Christian
Auteurs secondaires : Adaptations au Climat Tropical, Exercice et Santé (ACTES) ; Université des Antilles et de la Guyane (UAG) Laboratoire de Physiologie des Interactions ; CHU Arnaud de Villeneuve UPRES-EA ; Université Montpellier 1 (UM1)

Éditeur(s) : HAL CCSD ACSM
Résumé : International audience
PURPOSE AND METHODS: This study was designed to compare the physiological responses and performance of well trained cyclists riding with two different chainring designs, round or eccentric, during a brief and intense cycling exercise: an "all-out" 1-km laboratory test. The eccentrically designed chainring was made of two crank arms sliding into each other, with the inside arm fixed on the center of the arm of a circular chainring and the outside arm sliding along the inside and revolving around an elliptical cam. This design increases crank arm length at the downstroke and decreases it during the upstroke, thus increasing and decreasing the torque. In terms of the chainring's revolution, the crank arm length at 0 degrees and 180 degrees is similar to the arm length of circular chainrings (175 mm). However, during the downstroke (0-180 degrees ), it increases to its maximum length of 200 mm at 90 degrees and then returns to its original length of 175 mm at 180 degrees. During the upstroke, it decreases to a minimum length of 150 mm at 270 degrees and then increases to 175 mm at 360 degrees. Eleven cyclists performed an all-out 1-km laboratory test using each chainring. The study was conducted over two consecutive weeks with the order of chainring use randomized. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. Heart rate was measured using a telemetry system. RESULTS: None of the cardiorespiratory variables showed significant differences between chainring trials. Performance, however, was significantly improved using the eccentric design (64.25 +/- 1.05 vs 69.08 +/- 1.38 s, P < 0.004, with the eccentric and the round design, respectively). CONCLUSION: We concluded that the eccentric chainring significantly improved the cycling performance during an all-out 1-km test. Further testing with indoor cycling specialists performing on a velodrome would be helpful to define the maximal possibilities of such a chainring.
Medicine & Science in Sports & exercise

hal-00720551
https://hal.univ-antilles.fr/hal-00720551
https://hal.univ-antilles.fr/hal-00720551/document
https://hal.univ-antilles.fr/hal-00720551/file/Article.pdf

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