THE LAST PHASE OF THE CRAWL STROKE IS MORE IMPORTANT THAN THE FIRST PHASE (THE “FRONT QUADRANT”)
Formosa, D. P., Mason, B. R., & Burkett, B J. (2010). Measuring active drag within the different phases of front crawl swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.
"An elite swimmer’s success is primarily dependent upon the ability to minimize active drag, whilst optimizing propulsive force." This study quantified passive and active drag, as a force-time profile. It also examined the force-time profile to determine which parts of the stroke phase a swimmer produced minimum and maximum forces. Elite freestylers (N = 18) completed three maximum velocity trials, followed by three passive and active drag trials using a towing device mounted upon a force platform. The computed active drag and the propulsive force profiles were represented as a force-time graph synchronized with video footage, allowing identification of intra-cyclic force fluctuations.
The mean velocities were ~1.72 m/s for females and ~1.89 m/s for males. The mean passive drag for the females and males were ~49.7 N and ~78.9, respectively. The mean active drag for the females and males were ~164.4 N for females and ~228.4 N for males. There was significant variation between minimum and maximum propulsive force range for left and right stroke phases, between and within Ss. The mean minimum propulsive force was generated during the first ‘pull’ phase of the stroke cycle. The maximum propulsive force production occurred during the final ‘push’ phases of the stroke cycle.
Implication. This study demonstrated the importance of representing active drag as instantaneous force, rather than a mean value. That provides unique and valuable insight into the intra-cyclic force fluctuations within a stroke cycle. For the practitioner it verifies that it is of greater importance to improve the last phase of the crawl stroke (where forces are greatest) than the first phase. That implication contradicts the values that are often claimed for “front-quadrant” swimming.
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