ORIGINAL ARTICLE

Relation between preferred and optimal cadences during two hours of cycling in triathletes

S Argentin¹, C Hausswirth¹, T Bernard², F Bieuzen², J-M Leveque¹, A Couturier¹, R Lepers³

¹ Laboratoire de Biomécanique et de Physiologie, Institut National du Sport et de l’Education Physique, 75012 Paris, France
² EA 3162, Université de Toulon-Var, BP 132, 83957 La Garde, France
³ INSERM/ERIT-M 0207 Motricité-Plasticité UFR STAPS, Université de Bourgogne, BP 27877, 21078 Dijon Cedex, France

Correspondence to:
Correspondence to:
Dr Hausswirth
Institut National du Sport et de L’Education Physique (INSEP), Laboratoire de Biomecanique et de Physiologie, 11 Avenue du Tremblay, Paris 75012, France; christophe.hausswirth{at}wanadoo.fr

Objectives: To determine whether the integrated electromyographic signal of two lower limb muscles indicates preferred cadence during a two hour cycling task.

Methods: Eight male triathletes performed right isometric maximum voluntary contraction (MVC) knee extension and plantar flexion before (P1) and after (P2) a two hour laboratory cycle at 65% of maximal aerobic power. Freely chosen cadence (FCC) was also determined, also at 65% of maximal aerobic power, from five randomised three minute sessions at 50, 65, 80, 95, and 110 rpm. The integrated electromyographic signal of the vastus lateralis and gastrocnemius lateralis muscles was recorded during MVC and the cycle task.

Results: The FCC decreased significantly (p<0.01) from P1 (87.4 rpm) to P2 (68.6 rpm), towards the energetically optimal cadence. The latter did not vary significantly during the cycle task. MVC of the vastus lateralis and gastrocnemius lateralis decreased significantly (p<0.01) between P1 and P2 (by 13.5% and 9.6% respectively). The results indicate that muscle activation at constant power was not minimised at specific cadences. Only the gastrocnemius lateralis muscle was affected by a two hour cycling task (especially at 95 and 110 rpm), whereas vastus lateralis remained stable.

Conclusion: The decrease in FCC observed at the end of the cycle task may be due to changes in the muscle fibre recruitment pattern with increasing exercise duration and cadence.

Abbreviations: EOC, energetically optimal cadence; EMG, electromyography; FCC, freely chosen cadence; iEMG, integrated electromyography; MAP, maximal aerobic power; MVC, maximal voluntary contraction; RMS, root mean square; V^·O₂, oxygen uptake

Keywords: oxygen uptake; cadence; muscular torque; electromyography; cycling

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Commentary

F Vercruyssen⁴

⁴ Department of Sport Ergonomics and Performance, University of Toulon-Var, BP 132, 83957 La Garde cedex, France; vercruyssen{at}univ-tln.fr

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