Influence du cycle de propulsion sur les caracteristiques mecaniques observees lors d'un sprint en fauteuil roulant

• Published in: Science & sports 2002-05, Vol.17 (3), p.128-131
• Main Authors: Hintzy-Cloutier, F, Tordi, N, Rouillon, J-D, Belli, A
• Format: Article
• Language: English
• ISSN: 0765-1597
• DOI: 10.1016/S0765-1597(02)00130-2

Purpose- Since wheelchair propulsion involves both arms working in a simultaneous cyclic motion with an active and a recovery phase, the frequency of arm pushing can be varied without affecting the velocity of the wheelchair when the power output remains constant. The purpose of this study was to analyse the effects of frequency and timing characteristics on the mechanical parameters in wheelchair sprinting. Methods- The effects of both cycle frequency and timing on mechanical parameters were studied in 17 healthy women during wheelchair sprinting consisting of 9 all-out efforts of 8 s duration at different resistances (0-4 Nm). A wheelchair ergometer, allowing the measures of instantaneous force, velocity, power, frequency as well as the cycle push and recovery times, was used to investigate the mechanical and timing parameters of wheelchair sprinting. Results and discussion- The trends in the timing parameters were similar to velocity dependent trends described by previous maximal and submaximal wheelchair locomotion studies, i.e. the push and the overall cycle times decreased when the velocity increased, whereas the recovery time remained constant. In contrast, when the resistance increased the cycle frequency also increased. The work per push being maximal at each sprint resistance condition, the improvement of power output with increasing the resistance was possible by an increase in the cycle frequency. In addition, we found that subjects systematically used low or high frequencies to achieve the same power output regardless of the resistance. The results showed that the frequency type significantly modified the timing parameters while power output, velocity and force values were not affected. Conclusion- These results suggest that the maximal power output is not solely influenced by the individual frequency technique and thus future investigations must also consider the amount of work per push.Original Abstract: Introduction- La propulsion en fauteuil roulant etant simultanee, la frequence de propulsion peut varier sans affecter la vitesse de deplacement, pour un meme niveau de puissance fourni. Cette experimentation avait donc pour but d'etudier les effets de la frequence de cycle et des parametres temporels sur les caracteristiques mecaniques d'un sprint en fauteuil roulant. Methodes- Dix sept femmes en bonne sante ont realise 9 sprints d'une duree de 8 s contre differentes charges de friction (0-4 Nm). Le fauteuil roulant ergometrique utilise per