Hi Steve,

You are right that the speed skating suits have patches and
textures on it. These are meant to reduce the air resistance. With
the old-fashioned smooth suits, there was a laminar flow of air
around the body of the skaters. Because of the patches and
textures, this laminar flow is transformed into a turbulent flow. At
least, that is the idea behind these new suits. The drag force of the
body with a turbulent flow is considerably lower than with a laminar
flow of air. The effect of these suits is estimated to be about 0.1 to
0.2 seconds per round (400 m). Hence, the effect is a lot smaller
than the effect of the clap-skate which was thought to be 1 to 1.5
seconds per 400 m. But still, for the top skaters this difference is
considerable.

The development of these suits started at the Technical University
of Delft in the Netherlands in 1998, just before the winter olympics
in Nagano, Japan. At that time all athletes skated in regular, old
fashioned suits. The Dutch athletes were the first to stick separate
strips on their suits. These long strips were a few millimeters thick,
and about a centimeter wide. They were mounted on the medial
and lateral side of the legs and arms, on top of the head, and on
both sides of the trunk. There was quite some discussion about
these strips amongst the athletes; particularly about the fact that
the strips were only available for the Dutch skaters. This would give
them an unfair advantage. The ISU (Internation Skating Union)
thought about forbidding the athletes to skate on the olympics with
these strips on their suits. However, eventually, they permitted the
use of the strips, at the condition that all skaters could get free
access to the strips.

At the University of Delft the effect of these strips was confirmed in
a wind tunnel. During these tests, the skaters were standing in a
static skating position. Whether or not the strips have an effect on
the air flow depends on the location of the strips within the flow. In
a static position, the optimal location of the strips on the body
could be determined quite easily. However, during skating, the
body is in a dynamic situation, and all body parts move relative to
each other. Ideally, the locations of the strips on the body should
move during a stroke, as the position of the body parts within the
air flow changes during a stroke. This was not possible with the
initial strips. Hence, it was questionable whether the effect was as
big during skating, as it was in the wind tunnel experiments. At the
University of Delft, newer suits have been developed. The rather
narrow strips have been converted into a wide patch with a rough
texture. These patches are a part of the suit itself, no add-ons.
These wide patches ensure that there is always something in the
air flow that disturbes the laminar flow, and, hence, reduces the
drag. These suits are currently used by the norwegian skaters. The
Dutch and American skaters use suits that were developed by
Nike, that also consist of parts with different roughnesses. The
philosophy is the same. On the legs, arms, head and trunk, the
fabric has a high roughness. But around the armpits and the crotch
(excuse me for these words) the fabric is extremely smooth to
reduce friction between the bodyparts themselves. Other skaters
still use the original strips.

Whether or not the adaptations to the suits really have an effect on
the speed remains questionable. For sure, the adaptations do a
good job mentally. Such small technical improvements advance the
sport as a whole, and give the athletes the idea that there is still a
lot to gain. I guess these things make them strive for faster speed
skating records. Although the clap-skate caused a revolution in
speed skating, there are still a lot of technical improvements
possible where the ice, skates and suits are concerned. As a
mechanical engineer working in the field of biomechanics and
human movement science, I am very much interested in the
technical improvements in speed skating. However, being also a
speed skating coach and fanatic, I know that in the end the athlete
him or herself should do the job.

Feel free to contact me if you have any further questions about
speed skating.

Best wishes,

Jan Stolk

Orthopaedic Research Laboratory
University Medical Center Nijmegen
PO Box 9101
6500 HB The Netherlands
Tel: + 31 24 3616959
Fax: + 31 24 3540555
E-mail: jan@orth0044.azn.nl
or: stolk_j@yahoo.com

---------------------------------------------------------------------------------------------
On 15 Feb 2002, at 20:16, zeppo@IS2.DAL.CA wrote:

> In watching the Olympic speed skating competitions, I notice that many of
> the body suits the athletes are wearing seem to have special patches of
> textured material or other irregularities. Are these used to try to reduce
> drag from wind resistance somehow? I am assuming this would be similar to
> some of the textured swim suits seen in Sydney.
>
> Perhaps someone with insight into the body suit and/or bathing suit
> designs could enlighten us on the effectiveness of these "sartorial
> innovations".
>
> Steve LeBlanc MSc
> Instructor, School of Health and Human Performance, Dalhousie University
> Email: Steve.LeBlanc@dal.ca Webpage: http://is2.dal.ca/~zeppo/
> ================================================== =======================
> "I've done...questionable things. Nothing the god of biomechanics
> wouldn't let you into heaven for."
>
> ---------------------------------------------------------------
> To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
> For information and archives: http://isb.ri.ccf.org/biomch-l
> ---------------------------------------------------------------
>

---------------------------------------------------------------
To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
---------------------------------------------------------------