100m World Record
interest in the effect of wind in athletics began when I moved to
Perth, Western Australia for my PhD studies. Perth has a famous
afternoon seabreeze called the 'Fremantle Doctor' which always blows in
the summertime (because of heating of inland areas.) This breeze has a
strong influence on sports in Perth (eg. sailboarding is very popular).
In athletics, the breeze is particularly troublesome because the layout
of Perry Lakes stadium means that sprinters always run directly into
the wind. It is very difficult for sprinters to record a fast time and
qualify for the National Championships. On the plus side, Perth is a
'mecca' for pole vaulters. The strong and reliable tailwind makes for a
great training environment and an excellent venue for competition.
Wind Assistance in
is well known that sprinters run faster with a tailwind and slower with
a headwind. I was interested in how you go about converting
wind-assisted or wind-hindered performances into equivalent
performances with no wind. Several theoretical studies have been
conducted, but they have some doubtful assumptions which result in
differing conclusions. A definitive experimental
study was needed to settle the matter.
conducted a study of the effect of wind on 100m sprinters using
competition performances published in athletics magazines. (For this
experimental study, the data already existed!) The study showed that
the advantage of a 2.0 m/s tailwind (the legal limit for recognition of
records) is about 0.10 seconds. Also, the disadvantage of a headwind
was found to be greater than the advantage of a tailwind of the same
magnitude. (This effect is well known to middle and long distance
runners. These athletes have to run laps of the track and so they
prefer still conditions if they are aiming to run a fast time.) A wind
correction curve was produced, and this has been adopted by the
athletics community. (See, for example, "The Little Green Book"
published by Track & Field News.)
find out more about the wind assistance study, see:
N.P. (1994). The effect of wind on 100-m sprint times. Journal
of Applied Biomechanics, 10 (2), 110-131.
Wind assistance in the 100-m sprint. Track Technique,
Accuracy of Wind Readings
the sprint events, races are timed to the nearest 0.01 seconds and the
official wind reading is a 10 second measurement obtained from a single
wind gauge placed next to the track.
My wind assistance study indicated that if athletes are to be treated
fairly when recognising world records the official wind reading must be
accurate to ±0.2 m/s.
It has long been suspected that the official wind reading does not
always provide an accurate representation of the wind affecting the
athlete as they run down the track. A study of wind conditions at the Sydney
Athletic Centre showed that the accuracy of the official wind
reading is only about ±0.9 m/s. This is equivalent to an
accuracy in race time of about 0.05 seconds. Therefore, the occasional
injustice may arise in the recognition of world records. The accuracy
of the official wind reading could be improved to the required level by
using several wind gauges placed along both sides of the 100m straight.
An instantaneous wind measurement would be taken as the runners passed
by each wind gauge.
However, this approach would greatly increase the cost and complexity
of organising an event that meets the requirements for consideration of
to Masaki Wakai, Tom Reddin, Deena Rosalky, and Hassan Chalich for
helping out with this study.
find out more about the wind accuracy study, see:
N.P. (2000). Accuracy of windmeasurements in athletics. In "The
Engineering of Sport: Research Development and Innovation, Proceedings
of the 3rd International Conference on The Engineering of Sport,
Sydney, 10-12 June 2000",
A.J. Subic and S.J. Haake (Editors), Blackwell Science, Oxford 2000 pp.
World Record (10.49 sec)
unexpected outcome of the work on wind assistance was the discovery
that Florence Griffith-Joyners' 100m world record was an illegal
Flojo recorded 10.49 seconds in the quarterfinals at the 1988 US
Olympic Trials. This performance broke the existing world record by
0.27 seconds, and no other sprinter has come anywhere near the mark
since. However, the official wind reading was considered 'highly
suspect' by those who witnessed the race. The September 1988 issue of Track &
Field News had a column titled "Everyone Knows it's
Windy", which included the comment: "
It's hard to say which number caused the bigger gasp at the Trials,
Florence Griffith Joyners' 10.49 at the finish-line time indicator, or
the 0.0 which popped up on the mid-straight wind board".
doubts about the official wind reading (0.0) were confirmed by my study
of the 100m races at the Trials. Plots of race time
versus wind reading were examined for deviations from the expected
relation. The wind reading for Flojo's 10.49 race was clearly
anomalous. For all competitors in this race (not just Flojo), the race
time indicated that the wind reading should have been between +5.0 and
+7.0 m/s. The 10.49 performance was definitely wind-assisted. The real
world record should be the 10.61 performance that Flojo set in the
final at the 1988 US Olympic Trials.
the IAAF has not yet corrected the world record list. The April 1994
issue of Track & Field News had a column
in support of the findings, and since 1997 the International
Athletics Annual of the Association
of Track and Field Statisticians has listed Florence
Griffith-Joyner's 10.49 performance as "probably strongly wind
assisted, but recognised as a world record". In the 2003 edition
of IAAF World Records, Richard Hymans
concludes "this is a world record which should not have been ratified".
Many of those involved in running the 1988 US Olympic Trials were
opposed to the 10.49 performance being submitted to the IAAF. However,
the relevant paperwork was signed and the performance was ratified as a
It seems that common sense 'took a holiday' at this track meet.
find out more about Flojo's 100-m world record, see:
Was Flojo's 100-m world record wind-assisted? Track Technique,
127, 4052-4053; 4057.
Linthorne, N.P. (1995).
"The 100-m world record by Florence Griffith-Joyner at the 1988 US
Olympic Trials". Report for the International Amateur Athletic
Federation, June 1995. (62 pages)