Passive Drag in Young Swimmers: Effects of Body Composition, Morphology and Gliding Position.

Matteo Cortesi,Raffaele Scurati,Rocco Di Michele,Giorgio Gatta,Giovanni Michielon,Sandro Bartolomei

doi:10.3390/ijerph17062002

Matteo Cortesi, Raffaele Scurati + Show 4 more

Open Access

https://doi.org/10.3390/ijerph17062002

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Abstract

The passive drag (Dp) during swimming is affected by the swimmer’s morphology, body density and body position. We evaluated the relative contribution of morphology, body composition, and body position adjustments in the prediction of a swimmer’s Dp. This observational study examined a sample of 60 competitive swimmers (31 male and 29 female) with a mean (±SD) age of 15.4 ± 3.1 years. The swimmer’s Dp was measured using an electro-mechanical towing device and the body composition was assessed using a bioelectrical impedance analyser. Body lengths and circumferences were measured in both the standing position and the simulated streamlined position. Partial correlation analysis with age as a control variable showed that Dp was largely correlated (p < 0.05) with body mass, biacromial- and bi-iliac-breadth, streamline chest circumference and breadth. Body mass, Body Mass Index, chest circumference and streamline chest circumference showed a significant and moderate to strong effect (η2 > 0.55) on Dp. Body mass was the best predictor of Dp explaining 69% of the variability. These results indicate that swimmers with lower Dp values were: (i) slimmer, with lower fat and fat-free mass, (ii) thinner, with lower shoulder breadth, chest circumference, and streamline trunk diameters (iii), shorter, with lower streamline height. These findings can be used for talent identification in swimming, with particular reference to the gliding performance.

Highlights

Swimming velocity results from the interaction between the swimmer’s propulsion and drag factors
While controversial issues exist due to the difficulty to accurately measure the wetted surface area of the swimmer’s body [3,6], the literature largely agrees that the cross-sectional area, the length of the body and the body mass are the main parameters involved in determining the swimming Dp [3,7,8,9]
Since Dp is a multifactorial measure which is affected by different variables, we evaluated the relative contribution of morphology, body composition, and technical characteristics in the prediction of a swimmer’s Dp

Summary

Introduction

Swimming velocity results from the interaction between the swimmer’s propulsion and drag factors. The swimmer’s drag increases at least quadratically as velocity raises, thereby affecting the energy expenditure. Several studies considered the effects of the body structure and shape on the swimmer’s Dp, relating morphological indices such as height, arm span, chest, appendicular segmental circumferences, and body breadths to glide efficiency [2]. Close correlations were shown between Dp and body structure and shape, body mass, height and trunk diameters [3,4,5]. While controversial issues exist due to the difficulty to accurately measure the wetted surface area of the swimmer’s body [3,6], the literature largely agrees that the cross-sectional area, the length of the body and the body mass are the main parameters involved in determining the swimming Dp [3,7,8,9]

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