PATTERNS OF FORCE APPLICATION IN CRAWL STROKING DIFFER BUT THE RESULTS OF THIS STUDY NEED TO BE INTERPRETED CAUTIOUSLY
Seifert, L., Chollet, D., & Rouard, A. (2007). Swimming constraints and arm coordination. Human Movement Science, 26, 68-86.
This study investigated variables (organismic, environmental, and task constraints) and front crawl performance, focusing on arm coordination adaptations over increasing race paces. Forty-two swimmers (15 elite men, 15 mid-level men, and 12 elite women) performed seven self-paced front crawl swim trials (as if competitively swimming 1500 m, 800 m, 400 m, 200 m, 100 m, 50 m, and maximal velocity, respectively). The paces were race simulations over 25 m to avoid fatigue effects. Swim velocity, stroke rate, stroke length, and various arm stroke phases were determined. Arm coordination was quantified in terms of an index of coordination (IdC) based on the lag time between the propulsive phases of each arm. This measure quantified three possible coordination modes in the front crawl: opposition (the two arm propulsions were continuous), catch-up (an inertial lag occurred between the two arm propulsions), and superposition (the two arm propulsions overlapped).
With increasing race pace, swim velocity, stroke rate, and stroke length, the three groups showed a similar transition in arm coordination mode at the critical 200-m pace, which separated the long- and mid-pace pattern from the sprint-pace pattern. The 200-m pace was also characterized by a stroke rate close to 40 strokes/min. The finding that all three groups showed a similar adaptation of arm coordination suggested that race paces, swim velocity, stroke rate and stroke length reflect task variables that could be manipulated as control parameters, with race pace (R2 = .28) and stroke rate (R2 = .36) being the best predictors of changes in the index of coordination, although their contribution to performance variance was very small. On the other hand, only the elite men reached a velocity greater than 1.8 m/s and a stroke rate of 50 strokes/min. They did so using an overlapping stroke (superposition), which occurred because of the great forward resistance created when these swimmers achieved high velocity (an environmental constraint). Conversely, the elite women and mid-level men had shorter stroke lengths and maintained a time gap (an inertial lag) between the propulsions of the two arms throughout the increase in paces, with gender and expertise explaining 9.0% and 8.3% of the index of coordination changes, respectively.
Implication. Arm coordination cannot be interpreted solely from the index of coordination value but should be considered from the perspective of task, environmental, and organismic constraint variables. These variables could serve as control parameters in experiments aimed at understanding changes in arm coordination during the front crawl. In this context, catch-up coordination, which is often considered a mistake, was seen to be an adaptation to a relative constraint.
[The reader should treat the findings of this study with caution. The generalization of any results must be moderated by the nature of the samples. It is possible that specialists, with preferred racing distances, bias their swimming techniques toward one particular form of swimming (e.g., a distance specialist might introduce catch-up stroking to the sprint distances). This is perhaps best illustrated by Ian Thorpe, a great 200 m and up event swimmer with a catch-up stroke, although the duration of the inertial lag was quite short. When he attempted sprinting, he maintained the catch-up technique (possibly held back because of a dominant six-beat kick) and never approached the continuity of force application that is needed to excel in modern men’s sprint races.
What needs to be researched is differences between the stroking patterns of the world’s best swimmers for particular distances. If that were done, one feature that would be evident is that the very best women distance swimmers do not perform with a catch-up stroke. Some swam with opposition (e.g., Hannah Stockbauer, Kate Ziegler) but the majority (e.g., Janet Evans, Brooke Bennett, Laure Manaudou) performed with overlapping propulsive phases. Similarly, Inge De Bruijn was markedly overlapped in her races of 50 and 100 m but Libby Lenton demonstrated a brief catch-up stroke in a 200 m leg of a relay while Jodie Henry appeared to perform more with the arms in opposition over 100 m.
To approach the form of generalization hinted in this article, a different research design and subject pool would need to be employed.]
Return to Table of Contents for Biomechanics of Swimming.