The influence of air friction in speed skating

doi:10.1016/0021-9290(82)90081-1

Journal of Biomechanics

Volume 15, Issue 6, 1982, Pages 449-458

https://doi.org/10.1016/0021-9290(82)90081-1 Get rights and content

Abstract

With the use of a wind tunnel the air friction force F_w on six speed skaters of different body builds was measured. The dependence of the drag coefficient C_D on air velocity v and the influence of different skating postures on drag were investigated. At an air velocity of v = 12 m/sec, an angle between upper and lower leg of 110° and a horizontal trunk position, the measured air friction constant $k_{n} (= F_{w} v^{2})$ of all subjects was calculated from their height l and weight m according to the formula 0.0205 l³√m (standard error 2%). C_D and as a consequence k appeared to be strongly dependent on air velocity.

Expressions to correct k for other velocities and postures were derived and substituted into a power balance by which the influence of posture, ice condition, wind and altitude on performance was predicted.

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The effect of drafting on the aerodynamic drag of a long-track speed skater is investigated in-field, at the 400m ice-rink of Thialf, Heerenveen. The Ring of Fire system is used to measure the flow downstream of an elite, isolated skater at approximately 11 m/s, transiting repeatedly through a tunnel filled with Helium-filled soap bubble flow tracers. Large-scale stereoscopic particle image velocimetry is used at an acquisition frequency of 500 Hz to obtain the near to far wake up to 11 m distance behind the skater. Over these 11 m, the center of gravity of the wake can shift up to 10 cm laterally, depending on the phase of the skating motion, and it moves about 15 cm to the floor. The former suggests that a trailing skater should slightly adapt its trajectory to achieve the lowest aerodynamic drag by drafting. The drag reduction of a trailing skater is estimated from the measurements on the isolated rider, assuming that the trailing rider's drag reduction only stems from the loss in total pressure in the wake of the first rider. The drag reduction is obtained with varying lateral and longitudinal distance between the leading and hypothetical trailing rider. It is observed that the peak reduction (∼40%) steeply decays with increasing lateral offset: at an offset of 50 cm the reduction is negligible. Instead, with increasing longitudinal offset, the decay is more gradual: at a distance of 11 m the reduction of 17% remains significant. The in-field estimations of the drag reduction are supported by wind tunnel measurements conducted on scaled skater models. Finally, the results obtained on the ice-rink indicate that a trailing skater should follow a slightly wider trajectory of about 20 cm, in comparison to the leading skater, to achieve the peak drag reduction during the entire skating stroke.
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View full text

The influence of air friction in speed skating

Abstract

Maximal oxygen uptake at sea level and at 3090 m altitude in high school champion runners

J. appl. Physiol.

Energy cost of speed skating and efficiency of work against air resistance

J. appl. Physiol.

Equation of motion of a cyclist

J. appl. Physiol.: resp. envir. exercise Physiol.

Maximum aerobic capacity and running performance at altitude

J. appl. Physiol.

Selective glycogen depletion in skeletal muscle fibres of man following sustained contractions

J. Physiol.

Selective glycogen depletion pattern in human muscle fibres after exercise of varying intensity and at varying pedalling rates

J. Physiol

Wake blockage corrections in a closed wind tunnel for one or two wall-mounted models subject to separate flow

ARC-R. and M. No. 3649

Severe steady state exercise at sea level and altitude in Olympic oarsmen

Med. Sci. Sports

Een biomechanisch onderzoek van het schaatsen

Geneeskunde en Sport

A biomechanical model of speed skating

J. Human Movmt Studies