Karsai, I., Silva, A., Garrido, N., Louro, H., Leitao, L., Magyar, F., Angyan, L., & Alves, F. (2009). Comparative method to estimate propelling ability. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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"Producing propelling force in an efficient way in the right swimming direction is one of the key factors in competitive swimming. During the action the extremities of the swimmer give energy to the water molecules to accelerate them, to generate flow around and along the hand-arm complex to achieve the highest pressure difference in the right time and space. There are differences in morphological and physical characteristics between swimmers and there is an infinite number of possible motion variations to perform the crawl arm stroke. Difference should exist between swimmers and in the way they can exploit the potential of the fluid environment. Direct force measurement is impossible during free swimming and analytical investigations to date do not provide a useful method to calculate force production. Therefore, a special approach is necessary to express the level of the propelling ability."

Internationally recognized male swimmers (N = 8) performed a non-breathing, arm-only task on a special device which recorded force production. The legs were tied and supported. Velocity was increased incrementally until the S could maintain a stable rhythm. Four underwater cameras were used to record kinematic parameters and the APAS system was employed to calculate the 3D data for the analysis. Reference forces were calculated based on anthropometric and kinematic data. A 3-segment simple model without the C value was used to estimate drag resistance. Swimming direction was estimated from the measured force data. Test results and 100-m sprint velocity were correlated to evaluate the suitability of this analysis for predicting propelling ability.

Force production increased almost in a linear fashion and peaked at the higher end of moderate velocity and dropped considerably at the highest velocity. The ratio between the measured and the reference force at the starting velocity was almost constant for Ss across the velocity increments, with a slight peak at the third increment. Free swimming velocity was measured in 100 m distance (v = ~1.92 m/sec). There was a significant but low correlation between the calculated ratio and the velocity swum in 100m (r = 0.749).

Implication. Estimated propelling ability in an arms-only swimming device was related to ~50% of 100-m swimming performance variability. As a test alone for assessing swimming ability, it would have little use. Other factors need to be evaluated and added to a predictive equation. [It hasa long been known that arms-only swimming does not replicate the level of power production in free swimming (arms + legs). The 50% value was similar to that reported by Costill et al (Costill, D. L., King, D. S., Holdren, A., & Hargreaves, M. (1983). Sprint speed vs. swimming power. Swimming Technique, May-July, 20-22.) for power produced by swimming arms-only. When kicking is added, arm power increases. Thus, testing arms-only swimming is a questionable research strategy.]

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