The relationship between preferred and optimal cadences during 2-h cycling in triathletes

Sébastien Argentin (1) , Christophe Hausswirth (1) , Thierry Bernard (2) , François Bieuzen (2) , Jean-Michel Lévêque (1) , Antoine Couturier (1) , Romuald Lepers (3)

1 INSEP - Institut national du sport et de l'éducation physique
2 UTLN - Université de Toulon
3 CAPS - Cognition, Action, et Plasticité Sensorimotrice [Dijon - U1093]

Objectives: This study aimed to determine whether the integrated electromyographic (iEMG) signal of two lower limb muscles might indicate preferred cadence during a 2-hour cycling task. Methods: Eight male triathletes underwent right maximal isometric (MVC) knee extension and plantar flexion before (P1) and after (P2) a 2-h laboratory cycle (CT) at 65 % of maximal aerobic power (MAP). Freely chosen cadence (FCC) was also determined, also at 65 % of MAP, via five randomised 3-minute sessions at 50, 65, 80, 95, and110 rev.min-1. The iEMG of the vastus lateralis (VL) and gastrocnemius lateralis (GL) muscles was recorded during MVC and CT. Results: The FCC decreased (P<0.01) from P1 (87.4 rev.min-1) to P2 (68.6 rev.min-1), towards the energetically optimal cadence (EOC). This EOC did not vary significantly over CT. The MVC of VL and GL decreased (P<0.01) between P1 and P2 (by 13.5% and 9.6%, respectively). Our results indicated that muscle activation at constant power was not minimised at specific cadences. Only Gastrocnemius Lateralis muscle was affected by a 2-h cycling task (especially at 95 and 110 rev.min-1) whilst VL muscle was stable. Conclusion: The decrease in FCC observed at the end of CT may be due to changes in muscle fibre recruitment pattern with increasing exercise duration and cadence.

Mots clés: oxygen uptake; cadence; muscular torque; EMG

Domaines: Sport; Physiologie du sport

Sébastien Argentin, Christophe Hausswirth, Thierry Bernard, François Bieuzen, Jean-Michel Lévêque, et al.. The relationship between preferred and optimal cadences during 2-h cycling in triathletes. British Journal of Sports Medicine, 2006, 40, pp.293 - 298. ⟨10.1136/bjsm.2005.020487⟩. ⟨hal-01690098⟩