Affiliations: [a] Laboratoire de Modélisation des Activités
Sportives, Bourget du Lac, France | [b] Centre de Recherche et d'Innovation sur le Sport, Lyon
1, France
Note: [] Address for correspondence: Nicolas Horvais, Laboratoire de
Modélisation des Activités Sportives, Université de Savoie – CISM,
73 376 Bourget du Lac, France. Fax: +33 4 79 75 81 48; E-mail: nicolas.horvais@univ-savoie.fr
Abstract: This study analysed muscular, mechanical and physiological
parameters using a circular chainring (CC) and a non circular Osymetric
chainring (OC). OC was characterized by the use of a lower radius during top
and bottom dead center and a higher radius during downstroke and upstroke
phases. Twelve triathletes performed (i) an 8 min submaximal test and (ii) two
8 s maximal sprint tests. Gross efficiency was calculated during the submaximal
test. Instantaneous external force and pedalling rate were recorded and the
instantaneous net crank torque was calculated during both tests. Lower limb
muscles coordination pattern (timing and magnitude) were also recorded. During
the submaximal test, the only significant differences were the lower net crank
torque of OC vs. CC at 0° and
180° and the higher net crank torque of OC vs. CC at
90° (P< 0.05). Concerning the
sprint test, the only significant difference was the higher burst duration of
the biceps femoris muscle with OC (P< 0.05). Present
results indicate that OC facilitated mechanically the foot path
at 0° and 180°. Nevertheless,
this mechanical effect did not seem to be sufficient to improve performance
since the muscles coordination pattern was not modified.
