5 effects of resistance

Effects of Resistance

Forms of resistance Form Drag Wave Drag Frictional Drag

Effects of Resistance

Form Drag, also called profile drag, is influenced by your shape and the amount of cross sectional area you present to the water

Swimming in a head up position makes you unstreamlined because of form drag

Streamline reduces water (and air) resistance by reducing form drag

Form Drag

http://scuba-doc.com/propuls.html

Wave drag opposes you only when you swim at or within a few feet of the surface of the water and cause waves

Wave Drag


Frictional drag, also called surface drag, results when water flowing past you is slowed by contact with your surface material

Frictional Drag


Power output of swimmer (at constant velocity) determined by energy used to overcome drag (Pd) plus kinetic energy given to the water (Pk)Po = Pd + Pk

http://www2.fhs.usyd.edu.au/ess/sinclair/AB/2004abLC13web.pdf

Pd required for a given velocity (i.e. amount of drag) Power able to be delivered (physiological capacity) Propelling efficiency

Propelling efficiency is the ratio of useful power (to overcome drag) to total power

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Performance determined by:


Body size and shape Body alignment (skill) Body length (hull speed)

Drag increases proportional to the square of velocity drag = A x v2

A is a constant specific to each individual

Factors affecting drag force


Graph compares 1 swimmer (Inge de Bruin) with other swimmers measured on same system. Inge has smaller drag force for any given speed.

Elite Female Swimmers A=24 Elite Male Swimmers: A=30.5 Elite Male Triathletes: A=41.6

(Toussaint and Beek, 1992)

Factors affecting drag force

Schematic drawing of the MAD-system mounted in a 25 meter pool. (for a picture of the system mounted in a pool click here) The MAD-system allows the swimmer to push off from fixed pads with each stroke. These push-off pads are attached to a 22 meter long rod. The distance between the push-off pads can be adjusted (normally 1.35 m. The rod is mounted about 0.8 m below the water surface. The rod is connected to a force transducer enabling direct measurement of push-off forces for each stroke. Subjects use their arms only for propulsion; their legs are floated with a small buoy. If a constant swimming velocity is maintained, the mean propelling force equals the mean drag force. Hence, swimming one lap on the system yields one data-point for the velocity-drag-curve. (note: the cord leading to the calibration device is detached during drag-measurement).

Measurement of active drag

http://www.ifkb.nl/B4/drag.html

http://www.ifkb.nl/B4/swimres.html

MAD System


In pairs, open the video recording of your freestyle swimming stroke from the student database

Use the worksheet provided to analyze your stroke with your partner using the biomechanical principles you have learned so far

Video recording analysis

Theory: Centre of Gravity Prac: Competitive swimming stroke

development

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