Biomechanics and Medicine in Swimming XI

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adaptations to increased aquatic resistance. They also indicate that IdC is an interesting tool to assess motor control and motor learning, even though the links between coordination and propulsion and efficiency are not automatic. Therefore, if the coach’s goal is to relate coordination to performance, the effectiveness of inter-arm coordination (i.e. IdC value) should be analyzed with regard to some of the indicators of propulsive efficiency (power output, intra-cyclic speed variations, swim speed/hand speed ratio, stroke index, power output/ total power ratio). coordInAtIon And PerForMAnce: FleXIBIlItY– stABIlItY? As noted, the IdC value does not remain the same whatever the speed. Indeed, swimming speed is not uniform as the application of propulsive forces in water leads to acceleration and deceleration within the cycle, i.e. to intra-cyclic speed variations of the centre of gravity (Miller, 1975; Miyashita, 1971). The opposition mode of coordination thus appears as ‘theoretically’ ideal because it should allow propulsive continuity (assumed by the alternating actions of the two arms) and limit the intracyclic speed variations of the centre of gravity. In practice, there is not an ideal mode of coordination as inter-arm coordination changes with the task and environmental constraints. Moreover, an analysis of expert front crawl sprinters swimming from their slowest to their fastest speeds showed inter-individual variations in the range of inter-arm coordination modes and in speeds (Fig. 1). This raises the question: Is the expert swimmer an ultra-specialist in one stroke and one race distance or a swimmer with flexible behavior, able to win in several strokes and events (like L. Manaudou and M. Phelps)? Speed (m . a Figure 1. Quadratic regression between inter-arm coordination and speed for expert front crawl sprinters (adapted from Seifert & Chollet, 2009). -1 ) The results suggested four theoretical profiles (Fig. 2): 1) small scales of speed and coordination, 2) a small scale of speed and a large scale of coordination, 3) a large scale of speed and a small scale of coordination, and 4) large scales of speed and coordination. Speed Figure 2. Four profiles of relationship between coordination and speed (adapted from Seifert et al., 2009) chaPter1.invitedLectures The first profile corresponds to swimmers with little ‘motor flexibility’ in coordination and speed. These could be ‘ultra-specialists’, training mostly in one way. For example, because they train mostly for endurance, triathletes maintain their inter-arm coordination in catch-up mode with extremely negative values for IdC (Hue et al., 2003). The second profile corresponds to an ineffective high value for coordination, because high speed cannot be attained. As pointed out by Seifert et al. (2007a), some non-expert swimmers switch to superposition coordination mode because they spend more time with their hand in the propulsive phase, due to slow hand speed, but therefore do not generate high force. The third profile corresponds to swimmers with stable inter-arm coordination while reaching high speeds. These swimmers may be focused on the change in the ratio between stroke rate and stroke length. For example, Figure 3 shows one swimmer of the French team (participated in the 4 x 100m at the Atlanta Olympic Games in 1996) who kept his coordination stable with IdC close to the ‘theoretically’ more efficient coordination mode (i.e. opposition), mostly changing his stroke rate/ stroke length ratio. Figure 3. Changes in stroke rate (SR) and stroke length (SL) while index of coordination (IdC) remains stable during 7 x 25 m increased in speed. The fourth profile demonstrates that, the longer the coordination curve, the greater the swimmer’s range of coordination, indicating motor flexibility in coordination. Indeed, the higher the maximal coordination and the lower the minimal coordination of the curve, the more the swimmer is exploring human potential. To the coach, this indicates that the swimmer attains a range of speeds depending on the type of coordination mode: catch-up mode by using glide time, or superposition mode by overlapping the propulsive phases. From this perspective, the IdC value itself does not indicate the swimmer’s performance, but only the behavioral flexibility with respect to the interacting constraints (Newell, 1986; Seifert et al., 2007b). As suggested above, coordination should be related to other parameters of propulsive efficiency in order to draw conclusions about performance. On the other hand, race analyses have mostly pointed out that high performance is related to stability or minimal change in the stroking parameters, i.e. speed, stroke length and stroke rate (Sidney et al., 2010). Concerning arm coordination, expert swimmers showed relatively stable IdC values over the course of a race, whereas lower expertise and/or fatigue was indicated by an increase in IdC (Seifert et al., 2007a). For example, during a 100m race, Seifert et al. (2007a) observed that the non-expert swimmers (who seemed more tired as they took 8.5 s more than the experts to complete the 100m) increased IdC from opposition to superposition coordination in the last part of the 100m. According to Suito et al. (2008) and Toussaint et al. (2006), these changes in arm coordination may be related to lower hand speed, power output and propelling efficiency in the last part of the 100m (for the analyses of 37
BiomechanicsandmedicineinswimmingXi the 200m event, see Alberty et al. (2005); for the 400m, see Schnitzler et al. (2010)). Last, as regards the task and environmental constraints, coordination flexibility or/and stability are useful indicators of motor skill in swimming. WhY coordInAtIon? to Go ForWArd? or Also For FloAtInG And BreAthInG? As suggested in the introduction, the limbs are coordinated not only to propel the body forward, but also to facilitate or improve floating and breathing. For example, expert and non-expert swimmers having unilateral breathing patterns (every 2 or 4 strokes) showed an asymmetric coordination, which was most often related to breathing laterality (i.e. a preferential breathing side) and motor laterality (arm dominance) (Seifert et al., 2005). This means that catch-up coordination mostly occurred to the same side as breathing and arm dominance, while the swimmer showed superposition coordination to the other side. This coordination asymmetry was found to be greater in non-expert swimmers because the time spent inhaling led them to a lag time in propulsion (Lerda et al., 2001). Notably, non-experts prolonged the catch with the arms extended forward to facilitate head rotation during breathing and thus by catch-up to the breathing side. Conversely, swimmers with bilateral breathing patterns (every 3 or 5 strokes) tended to balance the arm coordination by distributing the asymmetries (Seifert et al., 2005). Thus, it may be advisable to vary the learning situations to encourage symmetric coordination, i.e. alternating tasks with unilateral, bilateral and frontal snorkel breathing. To confirm this hypothesis, breathing laterality was manipulated in non-expert swimmers by imposing seven breathing patterns, divided into unilateral patterns and bilateral patterns (Seifert et al., 2008). The authors showed that breathing to the preferential side led to an asymmetry, in contrast to the other breathing patterns, and the asymmetry was even greater when the swimmer breathed to his nonpreferential side (Seifert et al., 2008). Moreover, coordination was symmetric in patterns with breathing that was bilateral, axed (as in breathing with a frontal snorkel) or removed (as in apnoea). From this viewpoint, arm coordination was not only determined by propulsion but also by breathing and motor laterality, suggesting that instructors should help swimmers (i) to determine their preferred side for unilateral breathing and (ii) to adapt the breathing pattern (e.g. by using bilateral patterns, apnoea in sprint, frontal snorkel) during training sessions when coordination asymmetry is disturbing the stroke too much. conclusIon The main contribution of inter-limb coordination analysis over the past decade has been the development of a useful tool for understanding motor skills in swimming. The main findings can be summarized as follows: (i) there is no “correct” coordination but only coordination in relationship to interacting constraints, (ii) appropriate coordination is not synonymous with good propulsion because a certain coordination mode is also adopted to facilitate breathing or floating, and (iii) coordination is not the cause but mostly the consequence of these constraints, thus imposing a certain coordination mode does not guarantee high performance or efficiency. It is therefore advisable to analyse the organismic, task and environmental constraints leading to the current behaviour rather than considering an ‘ideal’ behaviour based on a ‘theoretical’ background. AcKnoWledGMent I thank Didier Chollet, my principal colleague, who initiated the research about inter-limb coordination and supported me and many PhD students to work on this topic. 38 reFerences Alberty, M., Sidney, M., Huot-Marchand, F., Hespel, J.M., & Pelayo. P. (2005). Intracyclic velocity variations and arm coordination during exhaustive exercise in front crawl stroke. International Journal of Sports Medicine, 26, 471-475. Chollet, D., Chalies, S. & Chatard, J.C. (2000). A new index of coordination for the crawl: description and usefulness. International Journal of Sports Medicine, 21, 54-59. Chollet, D., & Seifert, L. (2010). Inter-limb coordination in the four competitive strokes. In L., Seifert, D., Chollet, & I., Mujika (Eds) The world book of swimming: from science to performance, Nova Science Publishers, Hauppauge, New York, in press. Chollet, D., Seifert, L., Boulesteix, L., & Carter, M. (2006). Arm to leg coordination in elite butterfly swimmers. International Journal of Sports Medicine, 27, 322-329. Chollet, D., Seifert, L. & Carter, M. (2008). Arm coordination in elite backstroke swimmers. Journal of Sport Sciences, 26, 675-682. Chollet, D., Seifert, L., Leblanc, H., Boulesteix, L., & Carter, M. (2004). Evaluation of arm-leg coordination in flat breaststroke. International Journal of Sports Medicine, 25, 486-495. Davids, K., Button, C., & Bennett, S. (2008) Dynamics of skill acquisition – A constraints-led approach, Champaign, Illinois, Human Kinetics Publishers. Hue, O., Benavente, H., & Chollet, D. (2003). Swimming skill in triathletes and swimmers using the index of coordination. Journal of Human Movement Studies, 44, 107-120. Lerda, R., Cardelli, C., & Chollet D. (2001). Analysis of the interactions between breathing and arm actions in the front crawl. Journal of Human Movement Studies, 40, 129-144. Miller D. (1975). Biomechanics of swimming. Exercise and Sports Science Reviews, 3, 219-248. Miyashita M. (1971). An analysis of fluctuations of swimming speed. In J.P. Clarys & L. Lewillie (Eds) Swimming Science I, Brussels, University of Brussels, 53-57. Morais, P., Vilas-Boas, J.P., Seifert, L., Chollet, D., Keskinen, K.L., & Fernandes R. (2008). Relationship between energy cost and the index of coordination in front crawl – a pilot study, 16th FINA World Sports Medicine Congress, Journal of Sports Sciences, 26, (Suppl. 1), 11 Newell, K.M. (1986). Constraints on the development of coordination. In M.G. Wade & H.T.A. Whiting (Eds) Motor development in children: aspect of coordination and control, (pp. 341-360). Dordrecht, Nijhoff. Potdevin, F., Bril, B., Sidney, M., & Pelayo, P. (2006). Stroke frequency and arm coordination in front crawl swimming. International Journal of Sports Medicine, 27, 193-198. Schnitzler, C., Seifert, L., & Chollet, D. (2010) Arm coordination and performance level in 400-m front crawl, Research Quarterly for Exercise and Sport, in press. Schnitzler, C., Seifert, L., Ernwein, V., & Chollet, D. (2008). Intra-cyclic velocity variations as a tool to assess arm coordination adaptations in elite swimmers. International Journal of Sports Medicine, 29, 480-486. Seifert, L. Boulesteix, L., & Chollet, D. (2004). Effect of gender on the adaptation of arm coordination in front crawl. International Journal of Sports Medicine, 25, 217-223. Seifert, L., Chehensse, A., Tourny-Chollet, C., Lemaitre, F., & Chollet, D. (2008). Effect of breathing pattern on arm coordination symmetry in front crawl. Journal of Strength and Conditioning Research, 22, 1670-1676. Seifert, L., & Chollet, D. (2008). Inter-limbs coordination and constraints in swimming: a review. In N.P. Beaulieu (Ed) Physical activity and children: new research, Nova Science Publishers, Hauppauge, New York, 65-93. Seifert, L., & Chollet, D. (2009). Modelling spatial-temporal and coordinative parameters in swimming, Journal of Science and Medicine in Sport, 12, 495-499.
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Pahlen Norge AS Pahlen Norge AS Cha
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Biomechanics and Medicine in Swimming XI

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