Active and passive drag: the role of trunk incline (original) (raw)

A Comparison of Experimental and Analytical Procedures to Measure Passive Drag in Human Swimming

PloS one, 2015

The aim of this study was to compare the swimming hydrodynamics assessed with experimental and analytical procedures, as well as, to learn about the relative contributions of the friction drag and pressure drag to total passive drag. Sixty young talented swimmers (30 boys and 30 girls with 13.59±0.77 and 12.61±0.07 years-old, respectively) were assessed. Passive drag was assessed with inverse dynamics of the gliding decay speed. The theoretical modeling included a set of analytical procedures based on naval architecture adapted to human swimming. Linear regression models between experimental and analytical procedures showed a high correlation for both passive drag (Dp = 0.777*Df+pr; R2 = 0.90; R2a = 0.90; SEE = 8.528; P<0.001) and passive drag coefficient (CDp = 1.918*CDf+pr; R2 = 0.96; R2a = 0.96; SEE = 0.029; P<0.001). On average the difference between methods was -7.002N (95%CI: -40.480; 26.475) for the passive drag and 0.127 (95%CI: 0.007; 0.247) for the passive drag coeff...

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

International Journal of Environmental Research and Public Health, 2020

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 (η...

Active Drag and Physical Characteristics in Age Group Swimmers

2007

The purpose of this study was to identify the influence of body size and morphology in active drag (Da) in front crawl swimming. Seventeen male national level swimmers (age: 15.42 ± 0.53 years, height: 178.52 ± 7.42 cm, body mass: 66.82 ± 7.45 kg) were selected from a large pool (350) of swimmers evaluated using the velocity perturbation method. Inclusion criterion was having achieved the same maximal velocity in the test (1.78 m.s-1). Hydrodynamic variables showed large variation and were correlated to body mass and height. Height corrected for the squared body mass showed a strong negative association with Da (-0.810). Swimmers of equivalent performance level have different active hydrodynamic profiles, according to body size and morphological characteristics.

Passive and active drag of paralympic swimmers

2015

The aim of this thesis was to contribute to the development of an objective, evidence-based international classification system for para-swimmers by quantifying the effect of physical impairment on passive and active drag. The thesis comprises five studies. Study 1 identified a significant relationship between normalised passive drag and the para-swimmers’ International Paralympic Committee (IPC) Class, but an inconsistent difference in normalised passive drag between adjacent classes. High within-class variability in passive drag indicates that the current classification system does not always differentiate clearly between swimming groups. Study 2 found that anthropometric features of para-swimmers, such as height and body mass, differed significantly between IPC Classes, whereas Shoulder Width, Chest Depth, Shoulder Girth and Torso Girth did not. A weak correlation existed between para-swimmers’ anthropometry and their passive drag, which indicates that other factors, such as impa...

A Method of Quantifying Torso Shape to Assess Its Influence on Resistive Drag in Swimming

2019

Torso shape characteristics such as cross-sectional area, curvatures and indentations influence the pressure distribution of fluid flow around the torso. The purpose of this study was to introduce a new method of quantifying torso shape using photographic imaging. The contours of the torso in the frontal and sagittal planes were obtained by tracing photographs of the swimmers. Anterior, posterior and lateral flow lines were interpolated to samples spaced at 1mm vertically and used to determine continuous form gradients of four elite male swimmers. The maximum rate of change in cross-sectional area was estimated from chest-waist and waist-hip by modelling each vertical sample of the torso as an ellipse. The method provides implications for discussion with coaches and athletes and future research to determine the role of torso shape in talent identification and swimming performance.