Estimate of propulsive force in front crawl swimming in young athletes

We report the evolution of the coordination with velocity in front-crawl swimming which is used in competitions over a large range of distances (from 50 m up to 25 km in open-water races). Inside this single stroke, top-level swimmers show different patterns of arm organization. At low velocities, swimmers select an alternated stroke with gliding pauses during their propulsion. The relative duration of the gliding pauses on a stroke cycle is independent of the velocity in this first regime. Above a critical velocity, the relative duration of the gliding pauses starts to decrease as speed increases. Above a second critical velocity, the gliding pauses disappear and the swimmers start to superpose their propulsion phases. These three regimes are first revealed experimentally and then studied theoretically. It appears that below the first critical velocity, swimmers use a constant coordination index and vary their speed by varying their propulsive force to minimize their cost of propulsion. For larger velocities, swimmers use their maximum propulsive force and vary their recovery time to increase further their speed. The physical model developed is general and could be applied to understand other modes of locomotion.

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Is There Any Effect of Symmetry on Velocity of the Four Swimming Strokes?

Symmetry ◽

10.3390/sym14010012 ◽

2021 ◽

Vol 14 (1) ◽

pp. 12

Author(s):

Raul Filipe Bartolomeu ◽

Pedro Rodrigues ◽

Catarina Costa Santos ◽

Mário Jorge Costa ◽

Tiago Manuel Barbosa

Keyword(s):

Force Production ◽

Swimming Velocity ◽

Propulsive Force ◽

Front Crawl ◽

Pressure System ◽

Contralateral Limb ◽

The Mean ◽

Limb Asymmetry ◽

Different Characteristics ◽

Full Body

The different characteristics of the four swimming strokes affect the interplay between the four limbs, acting as a constraint to the force produced by each hand and foot. The purpose of this study was to analyze the symmetry of force production with a varying number of limbs in action and see its effect on velocity. Fifteen male swimmers performed four all-out bouts of 25-m swims in the four strokes in full-body stroke and segmental actions. A differential pressure system was used to measure the hands/feet propulsive force and a mechanical velocity meter was used to measure swimming velocity. Symmetry index was calculated based on the force values. All strokes and conditions presented contralateral limb asymmetries (ranging from 6.73% to 28% for the peak force and from 9.3% to 35.7% for the mean force). Backstroke was the most asymmetric stroke, followed-up by butterfly, front crawl, and breaststroke. Kicking conditions elicited the higher asymmetries compared with arm-pull conditions. No significant associations were found between asymmetries and velocity. The absence of such association suggests that, to a certain and unknown extent, swimming may benefit from contralateral limb asymmetry.

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