RESEARCH ARTICLE
On the apparent decrease in Olympic sprinter
reaction times
Payam Mirshams Shahshahani1*, David B. Lipps2, Andrzej T. Galecki3,4, James
A. Ashton-Miller1,2,3
1 Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of
America, 2 School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America,
3 Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States of America,
4 Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, United States of America
* mirshams@umich.edu
Abstract
Reaction times of Olympic sprinters provide insights into the most rapid of human response
times. To determine whether minimum reaction times have changed as athlete training has
become ever more specialized, we analyzed the results from the Olympic Games between
2004 and 2016. The results for the 100 m and 110 m hurdle events show that minimum reac-
tion times have systematically decreased between 2004 and 2016 for both sexes, with
women showing a marked decrease since 2008 that eliminated the sex difference in 2012.
Because overall race times have not systematically decreased between 2004 and 2016, the
most likely explanation for the apparent decrease in reaction times is a reduction in the pro-
prietary force thresholds used to calculate the reaction times based on force sensors in
starting blocks—and not the result of more specialized or effective training.
Introduction
The ability to rapidly respond to an external auditory stimulus is important when encounter-
ing emergent situations in daily activities such as driving or when operating machinery. Reac-
tion times of sprinters at the Olympic Games offer insights into the fastest human reaction
times because there is little question as to their states of arousal, motivation, learning or train-
ing [1]. (To avoid confusion, since this paper employs International Association of Athletics
Federation (IAAF) data on ‘reaction time’, that term is used throughout this paper rather than
the more usual scientific term ‘response time’.) It is unknown if the reaction times of sprinters
at the Olympic Games remain stable from year to year, or whether changes to the focused
training that athletes undergo in preparation for each Olympics can improve their reaction
times. Understanding the effect of this focused training on the fastest human reaction times
could provide insights into the trainability of athletes and other individuals for time-critical
situations.
Investigating potential sex differences in the fastest human reaction times in elite Olympic
sprinters has important implications on the design of human-machine interfaces for handling
time-critical behaviors. Such interfaces, as in the braking system of an automobile, often do
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OPEN ACCESS
Citation: Mirshams Shahshahani P, Lipps DB,
Galecki AT, Ashton-Miller JA (2018) On the
apparent decrease in Olympic sprinter reaction
times. PLoS ONE 13(6): e0198633. https://doi.org/
10.1371/journal.pone.0198633
Editor: Maria Francesca Piacentini, University of
Rome, ITALY
Received: February 13, 2018
Accepted: May 22, 2018
Published: June 27, 2018
Copyright: © 2018 Mirshams Shahshahani et al.
This is an open access article distributed under the
terms of the Creative Commons Attribution
License, which permits unrestricted use,
distribution, and reproduction in any medium,
provided the original author and source are
credited.
Data Availability Statement: All the raw data are
already available at the International Association of
Athletics Federations webpage at https://www.iaaf.
org/results. We also uploaded the dataset that we
used for this manuscript on the Deep Blue
webpage at https://deepblue.lib.umich.edu/data/
concern/generic_works/cr56n184r.
Funding: This work was supported by the Claude
Pepper Center Grant AG024824 from the National
Institute of Aging, (JAAM and ATG), https://www.
nia.nih.gov/. The funders had no role in study
not consider potential sex differences in reaction times despite women having faster auditory
latencies [2,3], shorter neural pathways [4] but less muscle strength [5]. A significant sex differ-
ence was found in the reported reaction times of sprinters at the 2008 Beijing Olympics
Games, but this may have been an artifact of the algorithm used to calculate the reaction times
[6]. One goal of this paper was to determine whether sex differences in reported reaction times
have occurred at other Olympic Games. A second goal was to determine whether reaction
times have decreased over Olympic years.
To measure reaction times on the Olympic Track Swiss Timing, a subsidiary of Omega SA,
uses their ASC3 (Automatic Start Control) false start detection system which includes instru-
mented starting blocks to measure the time course of the force applied by the sprinter to the
blocks with a precision of 1 ms following the starting gun. If this force, which their datasheet
shows can reach ~2 kN, exceeds a given (unpublished) force threshold before 100 ms has
elapsed from the onset of the start gun signal, a false start is registered (Rule 162, IAAF Com-
petition Rules). A reaction time is reported in the published Olympic results if the force crosses
the designated threshold after 100 ms, but no reaction time is reported in the event of a false
start (< 100 ms) or other reasons for disqualification.
Any longitudinal comparisons of reaction time of sprinters competing at the Olympic
Games between 2004 and 2016 is confounded by an IAAF rule change in 2010 (Rule 162.7,
IAAF Competition Rules) that disqualified any athlete who false started, rather than permit-
ting a second chance as the prior rule allowed. This change apparently led runners to adopt
slightly more conservative strategies in their reaction times in order to avoid disqualification
[7]. However, since there was no rule change between 2004 and 2008 or between 2012 and
2016, the results from those years should permit a direct comparison of athlete reaction times
independent of the rule change.
Methods
Official reaction times from every heat in the 100, 110, 200, 400 and 440 m track events in
2004, 2008, 2012 and 2016 were downloaded from the official IAAF web site. All names were
stripped from the record to blind the analyses and University of Michigan Institutional Review
Board Approval was received (Exempt—Not Regulated Research, HUM00135664, dated 9/8/
2017). Runners who were disqualified in a heat were excluded, as were those who did not start.
The reaction time (RT) data were positively skewed, so a power transformation (RT-1.5) was
used to obtain a normal distribution [6].
Since we are interested in the minimum human auditory reaction times, we focused the
analysis on the races with the shortest reaction times: in an initial analysis these proved to be
the 100 m and 100 and 110 m hurdles races (S2 Fig and S1 Table). Since one reaction time was
an outlier, exceeding 300 ms, we excluded it for being non-competitive; whether or not it was
included in the analyses would prove not to affect the results.
All data analyses were performed in R (a language and environment for statistical comput-
ing) version 3.4.2. Linear mixed-effect models (LMM) with a random intercept for each athlete
were fit to the data using the ‘nlme’ version 3.1–132 package. We allowed for different residual
variations for each Olympic year and sex. Likelihood Ratio and t-tests were used to examine
the roles of sex and year on an individual’s reaction time for the years 2004–2016. We only
considered the minimum reaction time for each athlete for a given Olympic year; Those results
were then back transformed to find the mean value as well as the -3SD minimum reaction
time values (S1 Text) by sex and year [6].
Official reaction time results for the athletes who competed in the 2004, 2008, 2012 and
2016 Olympic sprinting competitions were included in our analyses (Fig 1A). To account for
On the apparent decrease in Olympic sprinter reaction times
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design, data collection and analysis, decision to
publish, or preparation of the manuscript.
Competing interests: The authors have declared
that no competing interests exist.
Fig 1. Sprinter minimum reaction times by sex and year in the 2004–2016 Olympics. (A) Scatter plot of reaction
times by sex and year. The solid black circles and bars represent the mean and ±3SD reaction times after back-
transformation. The hatched area designates reaction times deemed by IAAF rule to be a false start. The number of
On the apparent decrease in Olympic sprinter reaction times
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repeated measures a mixed-effect model with Olympic year and sex (4- and 2-level factors,
respectively) was fit to the set of transformed minimum reaction times. A Likelihood Ratio
(LR) test revealed a significant interaction between Olympic year and sex [LR = 22.82,
p < 0.0001]. After considering the plots of the transformed minimum reaction times (Fig 1B),
the mixed effect model was simplified based on the results of likelihood ratio tests for nested
models. In particular the model was simplified by combining the 2004 and 2008 years into one
category both in main effect of year as well as in year by sex interaction terms [LR = 1.20,
p = 0.54].
Results
The coefficients for the resulting fixed effects can be seen in Table 1 and, when considered
with the results in Fig 1B, they suggest that reaction times decreased significantly in the more
recent Olympics. When only the 2012 and 2016 data were considered as the fixed effects in the
model, there remained significant year and sex differences, but the interaction was no longer
significant [LR = 2.54, p = 0.111]. This suggests that the large sex differences in 2004 and 2008,
which disappeared in 2012, drove the significant interaction term.
Discussion
Our starting point for this study was the finding by Lipps et al. [6] of a significant sex differ-
ence in the reaction times of sprinters at the 2008 Beijing Olympics. Natural questions were
whether this difference would persist at the 2012 London Olympics and whether ever more
focused training leads to slight decreases in reaction times for both men and women. The pres-
ent results showing the abrupt nature of the decrease for only women at the London Olympics
suggests something other than training may have been responsible. One explanation for the
apparent decrease in minimum reaction times from 2012 to 2016 is that both sexes became
more comfortable competing under the threat of disqualification imposed by the 2010 IAAF
rule change, and thereby became less conservative. If so, the results do not support this
false starts reported for the 100 m sprints, 100 m hurdles, and 110 m hurdles were: 1 false start in 2004 and 2008 each, 3
in 2012, and 2 in 2016. (B) Mean (±2SE) transformed minimum reaction times (s-1.5) by sex and year. The 100 ms false
start threshold when transformed becomes 31.6 s-1.5. The most parsimonious Linear Mixed-effect Model found to fit
the data used a random intercept for each athlete. The fixed effects consisted of Olympic year as a factor with 3 levels
(2004 and 2008 together, 2012, and 2016), Sex as a factor with 2 levels, with the interaction of Olympic year by sex. As a
check, the predicted mean values from the LMM were found (the black dots and dashed lines) and agreed well with the
original data (red and blue lines). Minimum reaction times decreased significantly by year (See Results section). Note
that the 2010 IAAF rule change decreed that any runner who false started would be disqualified from the race, and that
applied to the 2012 and 2016 Olympics.
https://doi.org/10.1371/journal.pone.0198633.g001
Table 1. Linear mixed-effect model for transformed minimum reaction times (s-1.5).
Fixed effect
Parameter estimate (s-1.5)
SE
p
Olympic year (2004, 2008)
13.28
0.22
<0.001
Olympic year (2012)
15.37
0.28
<0.001
Olympic year (2016)
17.68
0.3
<0.001
Olympic year (2004, 2008):Men
3.05
0.31
<0.001
Olympic year (2012):Men
0.51
0.35
0.16
Olympic year (2016):Men
1.3
0.39
0.001
The analysis shows that women’s reaction times decreased significantly each year from 2008 to 2012, and 2012 to
2016. However, men’s reaction times only decreased significantly from 2012 to 2016 (Fig 1B).
https://doi.org/10.1371/journal.pone.0198633.t001
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explanation because there is no systematic decrease in the race finish times between 2012 and
2016 (S1 Fig). A simpler explanation is that the decreasing reaction times between 2012 and
2016 might be due to a decrease in the force thresholds employed by Swiss Timing to calculate
the reaction times of the men and women [8]. It was suggested by Lipps et al. that a 22%
decrease in the force threshold could have eliminated the sex difference in the reported 2008
reaction time data [6]. The present data for the 2012 Olympics suggest that the force threshold
was indeed reduced for the women in 2012, but not the men; there was no significant sex dif-
ference in their reported reaction times, and the reaction times of the men did not change
between 2008 and 2012 (Table 1, Fig 1B). There is no physiologic reason why women should
be slower than men in their central auditory processing time [2]; put simply, their shorter
limbs mean the signal reaches the leg muscles more quickly than in men, but their smaller leg
muscles mean than it takes longer to develop a significant plantarflexion force against the start-
ing block [6]. This means that it may be fruitful for companies to re-examine how they detect a
false start with an automatic starting system. Our results suggest that the back-transformed
Mean - 3SD value should be set to 100 ms (S1 Text, Fig 1A).
The method for calculating reaction time can vary with the company awarded the timing
contract [9], so such a reduction is within the purview of Swiss Timing, who regard the force
threshold used as proprietary information [6]. The choice of this force threshold is an impor-
tant compromise for the quality of the athletic competitions. If the force threshold is set too
low, the slightest twitch could result in a false start being recorded by the IAAF-certified Start
Information System (SIS). This would not be practical because too many sprinters would be
disqualified and that would spoil the competition. If the force threshold is set too high, sprint-
ers would exhibit unreasonably long reaction times. Of course, in the most recent IAAF rules,
it is the starter that makes the final disqualification decision based on data from the SIS system
as well as whether the athlete initiated his/her starting action before the starter pulled the trig-
ger. Any motion that is not part of the continuous starting movement would simply result in a
caution the first time (Rule 162.7-Note (i), IAAF Competition Rules). The IAAF has been
examining SIS methods for detecting false starts. (see for example [10])
A limitation of this study is the absence of data for reaction times less than 100 ms because
the reaction times are not reported for false-starts. This, and not having access to the starting
block force-time curves, prevents an accurate calculation of the minimum human reaction
time for lower force thresholds than were used; in those cases reaction times could become less
than 100 ms.
We conclude that the apparent decrease in sprinter reaction times between 2004 and 2016
is caused by decreases in the force thresholds used to calculate the reaction time. The decrease
in both men’s and women’s reaction times after 2012 appears to reflect fine tuning of those
force thresholds by Swiss Timing rather than a decrease in the acoustic neuromuscular reac-
tion time of the athletes due to specialized training.
In terms of applicability of the results to other situations, a rapid acoustic reaction time can
be important, for example, when a driver needs to brake an automobile in an emergency after
hearing a warning horn. Our results suggest that the designer of mechanical or electronic
equipment to which humans are to be mechanically coupled should employ the lowest practi-
cal force threshold that does not disadvantage women.
Conclusions
We conclude that the apparent decrease in reaction times is due to a reduction in the proprie-
tary force thresholds used to calculate the reaction times, based on measurements from force
sensors in the starting blocks, not the result of more specialized or effective training.
On the apparent decrease in Olympic sprinter reaction times
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Supporting information
S1 Text. Why the Mean– 3SD value is a good estimate of minimum auditory reaction time
for Olympic false start detection in sprinting.
(DOCX)
S1 Fig. Distribution of overall ‘mark’ times by sex, year, and race type. IAAF terminology
designates the overall race time as the ‘mark’ time. The boxplot lines represent the median,
and the first and third quartiles. The vertical lines extend up to 1.5 times the interquartile dis-
tance from the top and bottom boxplot lines. The graph shows no systematic change in overall
race times with Olympic year for men or women.
(TIF)
S2 Fig. Transformed minimum reaction times for all the sprints in 2016. Distribution of
transformed minimum (min) reaction time in 2016 for 196, 46, 63, 148, 138, and 94 athletes
who competed in 100 m, 100 m hurdles, 110 m hurdles, 200 m, 400 m, and 400 m hurdles
respectively. The error bars show ±2SE. The shorter sprints (100 m, 100 m hurdles, and 110 m
hurdles) have significantly faster reaction times than the longer sprints (p = 0.0001). To view
the linear mixed effect model for this analysis, please refer to S1 Table.
(TIF)
S1 Table. Linear mixed-effect model results for transformed minimum reaction times for
all sprints in 2016. Transformed minimum reaction time results for the 100 m sprints was
chosen as the reference group. We can see that 100 m hurdles, and 110 m hurdles were not sig-
nificantly different than the reference. However, 200 m, 400 m, and 400 m hurdles were signif-
icantly different than the 100 m sprints.
(PDF)
Acknowledgments
All Olympic Game reaction times are publicly available and downloaded from the official
International Association of Athletic Federation webpage. We are grateful for the developers
of the R Core Team, and ‘nlme’, ‘ggplot2’ and ‘stargazer’ packages who have made their prod-
uct publicly available for free.
Author Contributions
Conceptualization: Payam Mirshams Shahshahani, David B. Lipps, Andrzej T. Galecki, James
A. Ashton-Miller.
Data curation: Payam Mirshams Shahshahani.
Formal analysis: Payam Mirshams Shahshahani, Andrzej T. Galecki.
Funding acquisition: Andrzej T. Galecki, James A. Ashton-Miller.
Investigation: Payam Mirshams Shahshahani.
Methodology: Payam Mirshams Shahshahani, Andrzej T. Galecki.
Project administration: Payam Mirshams Shahshahani.
Resources: James A. Ashton-Miller.
Software: Payam Mirshams Shahshahani.
Supervision: Andrzej T. Galecki, James A. Ashton-Miller.
On the apparent decrease in Olympic sprinter reaction times
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Validation: Payam Mirshams Shahshahani, Andrzej T. Galecki.
Visualization: Payam Mirshams Shahshahani.
Writing – original draft: Payam Mirshams Shahshahani, James A. Ashton-Miller.
Writing – review & editing: Payam Mirshams Shahshahani, David B. Lipps, Andrzej T.
Galecki, James A. Ashton-Miller.
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On the apparent decrease in Olympic sprinter reaction times.
Mirshams Shahshahani, Payam,Lipps, David B,Galecki, Andrzej T,Ashton-Miller, James A