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IAAF Sprint Start Research Project: Is the 100 ms limit still valid?

Authors:
Masaki Ishikawa at Osaka University of Health and Sport Sciences
Masaki Ishikawa
Paavo V Komi at University of Jyväskylä
Paavo V Komi
Jukka A Salmi
Jukka A Salmi
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37New Studies in Athletics • no. 1/2009
© by IAAF
24:1; 37-47, 2009
STUDY
Introduction
peed of reaction is a critical aspect
of many competitive sports, includ-
ing the sprint events in athletics. In
these events, the reaction time is considered
to be the time taken by the athlete to respond
to the start signal and begin pushing the start-
ing blocks. A simple auditory reaction such as
this is one of the fastest types of reaction,
although it is thought to be rarely less than
100 ms (THOMPSON et al., 1992). It is note-
worthy that this “definition” of reaction time
specifically focuses on the force production
on the blocks without necessarily referring to
IAAF Sprint Start Research
Project: Is the 100 ms limit
still valid?
By Paavo V. Komi, Masaki Ishikawa, Jukka Salmi
The current false start criterion used by
the IAAF is based on an assumed mini-
mum auditory reaction time. If an ath-
lete moves sooner than 100 ms after the
start signal, he/she is deemed to have
false-started. The purpose of this study,
which was commissioned by the IAAF,
was to examine neuromuscular reaction
to the auditory signal used in the sprint
start and to determine whether the
100 ms limit is correct. Seven national-
level Finnish sprinters took part. A com-
prehensive approach was used to study
force reaction on the blocks, the move-
ments of the arms and the activation
profiles of several muscles. The authors
found great variation in individual reac-
tion times and confirmed previous
reports of simple auditory reactions as
fast as 80 ms. They recommend that the
100 ms limit be lowered to 80 or 85 ms
and that the IAAF urgently examines
possibilities for detecting false starts
kinematically, so that judges’ decisions
are based on the first visible movement
regardless of the body part. This can be
done with a system of high-speed
cameras, which gives views of all the
athletes on the start line. With such a
system, it would be possible to change
the start rule so that no false starts are
permitted.
ABSTRACT Prof. Paavo V. Komi is the Founder of the
Neuromuscular Research Center,
Department of the Biology of Physical
Activity, University of Jyväskylä,
Jyväskylä, Finland.
Masaki Ishikawa, PhD, is a Senior Lec-
turer at Osaka University of Health and
Sport Sciences, Osaka, Japan. His
research topic is the neuromuscu-
loskeletal mechanics during human
locomotion.
Jukka Salmi is a Senior Researcher of the
Sports Technology Program at Neuro-
muscular Research Center, Department
of the Biology of Physical Activity, Uni-
versity of Jyväskylä, Jyväskylä, Finland.
AUTHORS
S
movements or force production of other body
parts, such as head, neck, trunk or arms.
Physiologically, reaction time depends on
several factors: arrival of the start signal stim-
ulus at the sensory organ, conversion by the
sensory organ to a neural signal, neural trans-
missions and processing, muscular activa-
tion, soft tissue compliance and the selection
of the external measurement parameter (Fig-
ure 1). Each of these factors has an associat-
ed processing time that contributes to the
overall reaction time.
The current false start criterion used by the
International Association of Athletics Federa-
tions is based on an assumed minimum audi-
tory reaction time of 100 ms (IAAF, 2003). If an
athlete moves sooner than 100 ms after the
start signal, the firing of the starter’s gun,
he/she is deemed to have false-started. Until
recently, the reaction movement was deemed
to have started when the threshold of 25kg of
force above the baseline in the set position
was reached on either of the blocks. This has
now been changed so the reaction move-
ment is judged by the steepness of the rise of
the force curve.
These criteria seem to consider that all the
human beings will have more or less similar
results to an auditory reaction test, such as
the sprint start. However, the influence of
auditory stimulus on the initiation of complex
motor tasks is not fully understood. There are
several studies showing that simple auditory
reaction times of less than 100 ms can be
achieved (MERO & KOMI, 1990; ROTHWELL
& VALLS-SOLE, 2002; PAIN & HIBBS, 2007;
BROWN et al., 2008).
The purpose of the present study was to
examine the neuromuscular reaction to the
auditory signal used in the sprint start and to
determine whether the current 100 ms limit is
still justified. A comprehensive approach was
New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
38
Figure 1: Sequence of the auditory evoked reaction
used to study the force reaction on the blocks
and, using sophisticated EMG and kinematic
approaches, the movements of the arms and
the activation profiles of several muscles during
the start movement.
Methods
Protocols
Seven Finnish national-level sprinters (four
males and three women: age 24 ± 3 years;
mass 71.2 ± 14.2kg; height 177 ± 7cm) par-
ticipated in this study. They had previously
been informed of the procedures and all the
associated risks and all gave written consent.
The measurements were included in the ath-
letes’ training and testing programmes as
planned by their individual coaches.
The study was conducted in the biome-
chanics laboratory of the Neuromuscular
Research Center, Department of Biology of
Physical Activity, University of Jyväskylä. This
laboratory is equipped, among other things,
with a unique 10m long force platform sys-
tem, composed of two rows of 1m long indi-
vidual force plates placed in series, row by
row. The force plate area continued as a free
space for an additional 40m. Thus, the ath-
letes were able to perform the start naturally,
like in a real sprint competition. The force
plate and the extended 40m are covered with
tartan surface.
In the measurements, the athletes per-
formed a total of five to eight sprint starts sim-
ilar to the real race starts. Thus the conditions
were as close as possible to real competi-
tions. Figure 2 depicts how the starting bocks
were positioned on the force-plates. The two
individual front and rear start blocks were
measured separately for both vertical (Fz) and
horizontal (Fy) components of the ground
reaction forces. Similar measurements were
performed for the arm actions, again in the Fz
and Fy directions.
Parameters
In addition to the recording of the Fz and Fy
ground reaction forces (right and left sides)
individually for both legs and arms using the
39New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
Figure 2: Schematics of the sprint start measurement
force plates, electromyogram (EMG) activities
from the erector spinae (ES), vastus medialis
(VM), soleus (SOL) and tibialis anterior (TA)
muscles of both legs were recorded using
bipolar miniature-size surface electrodes
(diameter 6mm, interelectrode distance
21mm; Blue Sensor N-00-S/25, Medicotest,
Olstykke, Denmark). These EMG data were
amplified using the EMG telemetric recording
system (bandwidth 10Hz to 1kHz per 3dB;
model 16-2, EISA, Freiburg, Germany) and
were stored simultaneously together with
kinetic data on a personal computer via an AD
converter (Sampling rate 2kHz; Power 1401,
Cambridge Electronics Design Ltd, England).
To determine when the initial reactions to the
start signal took place, all start movements
were video-recorded with two high-speed
cameras at 300 fps (A600, Basler AG, Ahrens-
burg, Germany) from the rear leg side and from
the 45º diagonally forward direction. Reflective
markers were placed on the head, shoulder,
elbow, hand, trochanter major, centre of
rotation of the knee, lateral malleolus, heel, and
fifth metatarsal head. These points were then
digitised automatically (Motus, Vicon Peak
Performance, USA) and used to determine the
onset of the initial start movement.
An electronic pulse from the set to the start
gun firing was used to synchronise the kinet-
ic, kinematics, and EMG data.
Analyses
EMG signals were first full-wave rectified
and then filtered (Butterworth 4-order low-
New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
40
Figure 3: Time course data of the kinetics (arm and leg forces) and EMGs during the sprint start
(The zero (first dotted line) is the onset of the start signal.) VM=vastus medialis, MG=medial
gastrocnemius, SOL=soleus, TA=tibialis anterior, Bicep=biceps femoris, Abd=rectus abdominis,
Bra=brachioradialis
pass filter: 75Hz). The onset of EMG was
determined by visual inspection of the filtered
EMG signal with the researcher deciding
when the signal had changed from baseline
during the set position.
The resultant force during the start move-
ment was calculated from Fz and Fy data for
determining the onset and the 25kg threshold
of the rise of the resultant force curve.
Values are presented as means and stan-
dard deviations (SD) unless otherwise stated.
Results
Figure 3 shows a typical example of the
time course of the force and EMG data during
the sprint start. Table 1 gives the mean and
fastest reaction times for each parameter. The
onset of the arm force reaction (69 ms) was
faster than that of the leg force reaction
(98 ms). The time to reach the force detection
level (25kg) delayed the reaction time by
approximately 35 ms compared to the onset
of the leg force reaction. In the fastest start
condition, the onset of the muscle activation
for the measured EMGs occurred earlier than
in 100 ms.
In the 25kg force level detection, three sub-
jects (subject02, subject04, subject07) had
reaction times less than 100 ms in their fastest
trial (Figures 4.1 to 4.7). Subject 7 showed
mean reaction times of less than 100 ms
although the timing of her 25kg force de-
tection level was not fast due to the slow force
development.
After the start signal, the head and wrist
began to move at 110 ms and 108 ms,
respectively (Table 1). Note the large stan-
dard deviations (17 and 20). The legs began
to move after the head and wrist movements.
Discussion
The main results of this study are as follows:
1. In response to the start signal, the mean
reaction time on the blocks required to
reach the 25kg force level was generally
longer than 100 ms. However, in several
trials three subjects did have reaction
41New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
Mean (SD) Fastest (SD)
Kinetics
Onset of leg force reaction 98 (23) 78 (27)
Onset of arm force reaction 69 (12) 49 (14)
Force detection (25kg level) 133 (21) 114 (29)
Kinematics
Head movement 110 (17) 101 (21)
Hand movement 108 (20) 104 (17)
EMG
Erector spinae 87 (33) 69 (30)
Vastus medialis 94 (16) 73 (19)
Medial gastrocnemius 96 (20) 82 (26)
Soleus 112 (20) 91 (17)
Tibialis anterior 74 (18) 59 (13)
* time from the auditory stimulus (n=7)
Table 1: Reaction times (ms)
New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
42
Figure 4.1: The time course data of the resultant forces for the arms and legs of subject 01
Figure 4.2: The time course data of the resultant forces for the arms and legs of subject 02
43New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
Figure 4.3: The time course data of the resultant forces for the arms and legs of subject 03
Figure 4.4: The time course data of the resultant forces for the arms and legs of subject 04
New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
44
Figure 4.5: The time course data of the resultant forces for the arms and legs of subject 05
Figure 4.6: The time course data of the resultant forces for the arms and legs of subject 06
times less than 100 ms. These would
have been considered as false starts
according to the criteria used by the IAAF.
2. The time to the onset of muscle activation
in the fastest start reaction condition was
60-80 ms.
As shown in Introduction, the neuromuscu-
lar response of the auditory reaction time dur-
ing a sprint start can be less than 100 ms.
Generally, after taking 3-6 ms for the start sig-
nal discharge to travel 1m to the ear of ath-
lete, the sound stimulus can reach the motor
cortex through the brain stem and auditory
cortex in the time of 65 ms. Thereafter, the
time from the motor cortex to the spinal cord
and to the leg muscles can take 20-30 ms.
Including the mechanical delay (5-10 ms), the
total auditory reaction time takes approxi-
mately 100 ms (Figure 1).
However, as shown in a previous study
(ROTHWELL & VALLS-SOLE, 2002), there is
evidence that simple auditory reaction time of
less than 100 ms can be achieved. For exam-
ple, the startle reflex is thought to alter the
information processing loops so that the audi-
tory and motor cortices are bypassed and a
prepared motor programme is released sub-
cortically (BROWN et al., 2008). In this way,
portions of the typical auditory motor pathway
are bypassed, resulting in a decrease of reac-
tion time.
The currently limit of 100 ms in the IAAF
rules can be questioned for several reasons.
Firstly, in addition to the present data, there
are also other reports that demonstrate that
values much below 100 ms are possible in
good sprinters (PAIN & HIBBS 2007 and
BROWN et al.,2008). Both of these studies
are objective and very convincing. In fact PAIN
& HIBBS (2007) went as far as suggesting
that the auditory reaction time in the sprint
start could be as low as 85 ms. Our experi-
ence supports this suggestion. Secondly,
there is no question that the IAAF “rule” of
45New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
Figure 4.7: The time course data of the resultant forces for the arms and legs of subject 07
100 ms is based on something other than real
neuromuscular-physiological evidence. This
minimum reaction time limit does not take into
consideration the size and gender differences
among athletes. As the limit threshold is
based more or less on the ability to produce
the force (e.g. 25kg), the women are not able
to reach this level as quickly as men (KOMI &
KARLSSON, 1977).
The limit gives a signal that training cannot
reduce the minimum reaction time of 100 ms
at 25kg force level. Our Figure 1 is an attempt
to describe schematically the sequence of
delays in the neuromuscular system to audi-
tory evoked reaction. There are important
points in this scheme. First, the most uncer-
tain time-delay takes place between brain-
stem and auditory cortex. It is likely that this
delay, shown to last up to 50 ms, can most
probably be interpreted to be under influence
of training, for example. As this delay takes
about half of the entire reaction time, any
experimental data to verify its true value and
possible adaptation to genetic as well as envi-
ronmental conditions are more than welcome.
Until this becomes possible we can only rely
on objectively measured reaction time data
that the total reaction time in the sprint start
can be below 85 ms.
The sprint start reaction time as measured
from the reaction forces on the blocks is very
unnatural. The start action following the “sta-
tionary” set position is not just an action of the
legs. It is a very comprehensive whole body
movement. The examined muscles in the pres-
ent study showed variable response times
above the base line (Table 1), ranging, for
example, from 59 ms (group average in the fast
condition for the tibialis anterior muscle) to
91 ms (in the soleus muscle). The large stan-
dard deviations shown in Table 1 emphasise
possibilities for even lower values. Knowing the
relatively low value of electromechanical delay
of 10-12 ms in humans (NICOLl & KOMI, 1996),
the total reaction time for some muscles can
be well below 100 ms. It is important to note
that in the present study many of the athletes
had acceptable motor times in the range of 75
to 80 ms and below for the Vastus lateralis,
Gastrocnemius and Soleus muscles. All these
muscles are responsible for extension move-
ment of the legs against the starting block.
Conclusions
The following conclusions can be drawn
from the present study:
1. Great individual differences can be
observed in reaction times.
2. Reaction time in the sprint start can be
lower than the 100 ms IAAF criteria. The
values can in some cases be even below
80 ms (see the schematic presentation in
Figure 5).
3. Reaction time in the sprint start is param-
eter dependent and has different values in
different body parts. The values are usual-
ly lower in the arms than the legs.
4. As the reaction to the auditory stimulus in
the sprint start involves activation of sever-
al muscles in the whole body and conse-
quently activation and movement in the
various body parts (e.g. neck, head, shoul-
der, arms, back, abdomen, hip, knee and
ankle), the current application of the IAAF
rule does not take this important “whole
body involvement “ into consideration.
New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
46
Figure 5: The schematics of the possibilities
for the faster reaction (The horizontally sha-
ded area shows the reaction times that have
been observed experimentally in the sprint
start.)
5. As the start of muscle activation is the first
neuromuscular parameter to trigger the
joint movement (and force production),
the resulting kinematic changes should be
considered as a key possibility for solving
the complex problem of the current false
start criteria.
Recommendations for the IAAF
1. As the present study gives essentially the
same results as the ones published by
independent researchers in Britain (PAIN &
HIBBS, 2007) and Canada (BROWN et
al., 2008), it is now recommended that the
IAAF abandon the 100 ms minimum sprint
reaction time level and its measurement
with the current technical devices.
2. The level should be lowered to 80 or
85 ms, even if the block force production
is still used as the parameter to set the
level.
3. The IAAF should urgently examine possi-
bilities for detecting the false start kine-
matically, so that the decision is based on
the first visible movement regardless of
the body part. This can be done with a
system of high-speed cameras, which
gives views of all the athletes on the start
line. Modern technical possibilities are
numerous in this regard, and the human
eye can be considered as best to differen-
tiate the first movement (shown by the
high-speed camera) before the set mini-
mum reaction time. Figure 6 is our sug-
gestion for how the development project
could be started. The figure does not
show the cables to the monitor centre, in
which one or two persons can make the
decision a posteriori, but within 10-15
seconds after the gun firing.
4. Achieving point 3 above would lead to the
situation where the rule could be changed
so that no false starts are permitted.
Please send all correspondence to:
Prof. Paavo V. Komi
Paavo.Komi@sport.jyu.fi
47New Studies in Athletics • no. 1/2009
IAAF Sprint Start Research Project: Is the 100 ms limit still valid?
Figure 6: The schema of the proposed
camera detection system
BROWN, A.M.; KENWELL, Z.R.; MARAJ, B.K. &
COLLINS, D.F. (2008). "Go" signal intensity influences the
sprint start. Med Sci Sports Exerc, 40, 1142-1148.
IAAF (2003). Technical rules for international competitions
(available at: http://www.iaaf.org/newsfiles/23484.pdf).
KOMI, P.V. & KARLSSON, J. (1978). Skeletal muscle fibre
types, enzyme activities and physical performance in young
males and females. Acta Physiol Scand, 103, 210-218.
MERO A. & KOMI, P.V. (1990). Reaction time and electromyo-
graphic activity during a sprint start. European Journal of
Applied Physiology and Occupational Physiology, 61, 73 – 80.
NICOL, C. & KOMI, P.V. (1998). Significance of passively
induced stretch reflexes on achilles tendon force enhance-
ment. Muscle Nerve, 21, 1546-1548.
PAIN, M.G. & HIBBS, A. (2007). Sprint starts and the min-
imum auditory reaction time. Journal of Sports Sciences,
25, 79 – 86.
ROTHWELL, J.C. & VALLS-SOLE, J. (2002). The startle
reflex, voluntary movement, and the reticulospinal tract. In
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THOMPSON, P.D.; COLEBATCH, J.G.; BROWN, P.;
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REFERENCES
... Currently, the World Athletics (WA) federation false start rule states that a sprinter is automatically disqualified when the official starter confirms that they registered a SSRT < 100 ms after the gun. However, research suggests the minimum SSRT may be shorter than 100 ms false start threshold (Komi et al., 2009) while other studies suggest the threshold be longer due to the limitations of existing technologies and the rules on false starts (Brosnan et al., 2017). Establishing the true limits on SSRT requires detailed mapping the muscular sequence of activation and quantifying delay periods during the sprint start. ...
... Examining the sequence of muscle activation and the mechanical response delays may contribute toward the debate surrounding the WA 100 ms false start threshold currently implemented in competition worldwide. Research from Komi et al. (2009) proposed FDT as an element in this delay sequence and estimated it to constitute approximately 5-10 ms of the response time process. Consequently, this study aims to map out the kinetic and muscular response sequence of the sprint start. ...
... This ankle mechanical delay period is variable between sprinters. However, estimates of this delay period constituting 5-10 ms appear valid (Komi et al. 2009), with 7 ms the lowest value observed in the current study. Lower values of FDT may be expected in sprinters of World-class level. ...
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Establishing the limits of sprint start response time (SSRT) requires the mapping of the muscular sequence of activation and mechanical response delays and was the aim of the current study. Sprint start performance of 15 sprinters was examined with kinematic, EMG, and block force data collected. A general muscle activation sequence was identified, with both deltoid muscles, the rear leg rectus femoris, and the rear leg tibialis anterior the first muscles to increase activation from the set position. With ankle dorsiflexion the initial motion during the block push, examining the period between tibialis anterior muscle onset and block force onset is critical for quantifying mechanical response delays. Estimates of this delay period were as low as 7 ms which has implications for our understanding of the minimum SSRT a sprinter can legally produce.
View
... The use of different technologies to deliver the start signal and to detect RT could have an impact on specific components of RT and could explain the variable results across studies. Some studies claim that the minimum RT is shorter than the current 100 ms false start threshold [10][11][12], while other studies suggest the 100 ms false start threshold should be increased [13,14]. This emphasizes the difficulties in determining a universally agreed minimum RT in athletics since SIS technologies [5,12], sex [14] and expertise [15] could have an impact on RT. ...
... The precise details of event detection algorithms are not made public by SIS manufacturers [14] and in the absence of a reference criterion, the use of different algorithms can be expected. Most of the scientific studies use a simple arbitrary force threshold to assess RT [10,14,[32][33][34][35], or use a simple threshold computed using the mean and standard deviation or a predetermined percentage threshold of the baseline signal [5,[36][37][38][39][40]. ...
... RT differences resulting from the use of different event detection algorithms highlight a technological component of RT determination, which should be standardized to ensure validity across the various SIS. Some studies overcame the computational problem of RT detection by using a visual determination of the first detectable change in the force or acceleration curve signal [10,[42][43][44]. The RT difference between visual detection and one certified SIS was 7 ms for women and 11 ms for men on average [43] and 35 ms between visual detection and a simple force threshold [10]. ...
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The sprint start in athletics is strictly controlled to ensure the fairness of competition. World athletics (WA)-certified start information systems (SIS) record athletes’ response times in competition to ensure that no athletes gain an unfair advantage by responding in < 100 ms after the start signal. This critical review examines the legitimacy of the 100 ms rule, the factors that affect response times and the technologies and rules that support the regulation of the start in competition. The review shows that several SIS use different technologies to deliver the start signal and record response time (RT). The lack of scien- tific evidence about the definition of the 100 ms false start threshold by the WA is criticized in the literature and the 100 ms rule is challenged. SIS technologies, expertise and sex appear to affect the RT detected in competition. A lack of standardi- zation in event detection has led to validity and reliability problems in RT determination. The onset of the foot response on the blocks is currently used to assess RT in athletics via block-mounted sensors; however, research shows that the onset of arm force reaction is the first detectable biomechanical event in the start. Further research and development should consider whether the onset of arm force can be used to improve the false start detection in competition. Further research is also needed to develop a precise understanding of the event sequence and motor control of the start to improve the SIS technology and rigorously determine the minimum limit of RT in the sprint start.
View
... Mapping and measuring the sequence of physiological and mechanical delays is important for a precise understanding of the SSRT. Research to date has demonstrated that SSRT is dependent on several factors: the time taken for the start signal stimulus to arrive at the sensory organ, the delay for conversion by the sensory organ to a neural signal, the delays for neural transmissions and processing, activation of the muscles, soft tissue compliance and selection of the external measurement parameter used to detect the response (Komi, Ishikawa, & Salmi, 2009). Signal processing time encompasses the delays between the stimulus onset and muscle activation. ...
... In the sprint start, the athlete's muscles tend to be pre-tensed in the 'set' position and this may effectively reduce the inherent series elastic slack, a central component of EMD. Despite this, EMD has been proposed as a contributing factor to SSRT that may constitute approximately 10 ms of the delay process ( Komi et al., 2009). Sprint training aims to increase the rate of force development and therefore could reduce mechanical delays in force generation such as EMD. ...
... The IAAF false start limit of 100 ms is based on an assumed minimum auditory response time, and the validity of this limit has also been questioned. Komi et al. (2009) proposed that genuine SSRT's lower than the 100 ms IAAF criteria, potentially as low as 80-85 ms, are possible. Based on the assertions of Komi et al. (2009) that mechanical delays appear to be a component of SSRT, an investigation of the influence these components have on SSRT (i.e. ...
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In the sprint start, a defined sequence of distinct response delays occurs before the athlete produces a movement response. Excitation of lower limb muscles occurs prior to force production against the blocks, culminating in a movement response. The time delay between muscle excitation and movement, electromechanical delay (EMD), is considered to influence sprint start response time (SSRT). This study examined the delay in sprint start performance from EMD of the triceps surae muscle and examined whether certain sprinters gain an advantage in SSRT. Nineteen experienced sprinters performed sprint starts from blocks, with SSRT measured by an International Association of Athletics Federations (IAAF)-approved starting block system. EMD times were detected during a heel-lift experiment. Using revised SSRT limits, based on concerns over the validity of the IAAF 100 ms false start limit, EMD produced a significant moderate correlation with SSRT (r = 0.572, p = 0.011). Regression analysis determined that together, EMD and signal processing time (the delay between the auditory signal and muscle excitation) accounted for 37% of the variance in SSRT. Initial results suggest EMD is part of the response time process and that certain athletes may gain a performance advantage due to reduced EMD.
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... e reaction time is not only affected by innate factors, such as the athlete's nerve and muscle types, but is also influenced by training and psychological factors [4]. In sprinting events, the reaction time is influenced by the following factors: the time required for the start signal stimulus to reach the receptors, the delay time for the receptors to convert the stimulus into nerve signals, neurotransmission and processing, the activation of the delayed muscles, the soft tissue adaptability, and the external measurement parameters [5]. e reaction time refers to the shortest time from the reception of the stimulus to the response. ...
... After leaving the starting block, it takes a world-class 100-meter sprinter 5% of the total race time to reach 1/3 of his or her maximum speed. e starting performance of the sprinter is closely related to the total race time [5]. rough the analysis of the fitted model, the elastic coefficient of the athlete's reaction time to the athletic performance is 0.4644. ...
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Article
Full-text available
In sprint track events, the starting reaction time is an important professional capacity of the athletes, and it is closely related to their performance. This study examines the reaction time and the results of the male and female sprinters participating in the World Athletics Championships from 2011 to 2019 in the 100 m, 200 m, 100 m, and 110 m hurdles. The researchers used least squares estimation, multivariate analysis of variance, and other methods and theories to construct a double logarithmic model and a multivariate analysis of a variance model. The researchers used Econometrics Views and SPSS software programs to analyze the correlation between the performance and the starting reaction time, as well as the patterns in the changes of the reaction time of athletes of both genders in different types of and rounds in the competitions. Research results show that there is a direct correlation between the reaction time and the performance, and the degrees of correlation vary depending on the gender of the athlete, year of competition, type of competition, and round of competition. There is a correlation between the foul types and the type of competition, but there is no correlation between foul types and the gender of the athlete. The research results are science-based and are of practical value and thus can be used as a reference by coaches in sprint running to offer more professional guidance to the athletes.
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... According to World Athletics (WA) standards outlined in rule 162, reaction time must exceed 0.1s to ensure the integrity of the race [7]. However, the limits of the regulation are recently underlined in literature showing the necessity to develop a new multiparametric figure of merit able of including different important aspects to ensure fairness and equal treatment on starting blocks, as the upper limbs contribution and the physical characteristics of the athletes [8][9][10][11]. ...
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... The results support the implementation of the new SIS since the current SIS technologies and WA sprint start regulations failed to detect all the false starts. The results also showed that the new custom algorithm did not induce delays in RT detection in comparison with previous event detection algorithms used by SIS (Komi et al., 2009;Lipps, et al.,2011;Pain & Hibbs, 2007). ...
CONTRIBUTION OF NEW START INFORMATION SYSTEM PROTOTYPE TO THE FALSE START DETECTION IN ATHLETICS
Conference Paper
Full-text available
  • Jul 2020
This study aimed at comparing a prototype of a new Start Information System (SIS) with a World Athletics (WA) certified SIS which was used in competition. Twenty sprinters performed sprints under simulated race conditions. Response time (RT) was recorded by the WA certified SIS and the new SIS prototype based on a custom force plate and a new event detection algorithm to assess RT as the onset of arm force reaction. The mean value from RT recorded by the new SIS prototype for trials for which the RT given by the WA certified SIS were ranged between 100 ms and 119 ms (RT WA 100-119 ms) was 0.047±0.019 s. This result highlighted RTWA 100-119 ms were probably false start according to the theoretical minimum auditory RT, despite being valid by the current WA regulation. The revisited new SIS prototype technologies were more appropriate to detect false start in athletics.
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... Nonetheless, there remain some critical methodological issues in the calculation of sprint start performance parameters: First, the most common signal type used is ground reaction force (GRF) signals (Brown, Kenwell, Maraj, & Collins, 2008;Coh, Peharec, Bačić, & Mackala, 2017;Fortier, Basset, Mbourou, Favérial, & Teasdale, 2005;Henry, 1952;Mero & Komi, 1990;Taboga, Grabowski, di Prampero, & Kram, 2014;Willwacher et al., 2016); however, the force sensor-based methods did not consider the effect of force production capacities of the sprinters' arms on the RT calculation (Komi, Ishikawa, & Salmi, 2009). Second, another signal type used to calculate start performance involves using kinematic signals measured by high-speed cameras (e.g., Bezodis, Salo, & Trewartha, 2014;Bradshaw, Maulder, & Keogh, 2007;Ciacci, Merni, Bartolomei, & Michele, 2017;Maulder, Bradshaw, & Keogh, 2008); however, it has been reported that visually checking slow movie files to detect the onset instant in the action delays the measurement of RT compared to GRF measurements in block starts (Pain & Hibbs, 2007). ...
Validity of block start performance without arm forces or by kinematics-only methods
Article
  • Apr 2019
The purpose of this study was to validate the calculation of reaction time (RT) and normalised power in block starts without considering arm ground reaction forces (GRFs) or using two kinematics-only methods. The RT and normalised power in the action phase were calculated using four different methods: using GRFs of arms and legs by force plates (whole F-based method), which can be regarded as the most valid method, using GRFs of legs captured by force plates (legs F-based method), using position of the centre of mass of the entire body captured by high-speed cameras (whole P-based method), and using only a partial subset of segment position (partial P-based method). Bland–Altman plots demonstrated that the RT of the legs F-based method was not similar to that of the whole F-based method: the mean difference was 7.4 ms and the 95% limits of agreement was−45.1 to 59.8 ms, and it was the least valid method for the calculation among the four methods. In contrast, the normalised power was more valid in the legs F-based method, followed by whole and partial P-based methods. This information will help researchers and practitioners to decide upon their analysis methods when analysing block start performance.
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Age-Related Differences in Electromyographic Latencies of the Lower Limb Muscles in Standing Sprint Initiation in Boys During Childhood and Adolescence
Article
  • Feb 2025
  • PEDIATR EXERC SCI
Purpose: The aim of our study was to investigate age-related differences in childhood and adolescent boys' performance, including initial reaction time and electromyographic (EMG) latencies of leg muscles during sprint start. Methods: Forty-six Japanese boys, aged 5-19 years, participated in this study. The participants performed 5 consecutive 2-m sprints, starting with the boys' preferred split-stance starting posture. Ground reaction force data of the front and rear feet and surface EMG data of the rectus femoris, biceps femoris, and gastrocnemius muscles in both legs of all participants were measured using a wireless EMG system. Results: As chronological age increased, the initial reaction time was largely shortened until the breakpoint age of 8.6 years and was moderately shortened thereafter. The EMG latencies of the posterior thigh and shank muscles of the rear leg were also shortened largely long before reaching the adolescence; in contrast, those of the front leg muscles were largely shortened until adolescence. Conclusions: Reaction behavior with complex whole-body motion may develop long before the onset of adolescence. In particular, adjusting the rear leg motion may contribute to the rapid development of whole-body reaction maturation.
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High-responsiveness and -precision 3D NIR visual-assisted eye-pupil tracking robot for free-style ophthalmic OCT imaging
Article
Full-text available
Optical coherence tomography (OCT) has revolutionized noninvasive imaging in ophthalmology, enabling high-resolution, three-dimensional visualization of tissue microstructures. However, conventional ophthalmic OCT devices depend heavily on patient cooperation and operator expertise, hindering further applications, especially ophthalmic imaging for the disabled. Here we proposed a high-responsiveness and -precision three-dimensional (3D) near-infrared visual-assisted eye-pupil tracking robot for free-style ophthalmic OCT to address these limitations. This system incorporates 3D pupil tracking for automatic gaze alignment with a multi-functional and -wavelength scanning pod, enabling precise, real-time 3D tracking and alignment of the OCT scanning pod to the human eye pupil in customized orientations and positions. Our system achieves a response time of 21.26 ms for visual perception and 21.64 ms for robotic motion, with lateral accuracy of 14.15 μm, axial accuracy of 27.09 μm, and rotational accuracy of 0.26 degrees for free-style human ophthalmic OCT imaging. Our robotic system overcomes the scenario limitations of fixed devices, the high operator demands, and the imaging instability of handheld devices. It is expected to significantly expand the application scenarios and target groups for ophthalmic OCT imaging, improving the quality of ophthalmic healthcare services and enhancing patient experience.
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A METHOD COMPARISON OF BLOCK BASED ACCELEROMETERS AND FORCE SENSORS FOR DETERMINATION OF RESPONSE TIMES IN THE SPRINT START
Conference Paper
Full-text available
  • Jul 2020
This study compares sprint start response times (RT) derived from load cells in the blocks with a RT from rail mounted accelerometer using methods similar to World Athletics (WA) approved start information systems (SIS). Seven national and international sprinters completed sprint trials that replicated race competition start procedures. Load cells were incorporated into starting blocks and the back block RT were determined using: visual inspection (Visual RT), a 3SD threshold and CUSUM method, the rail accelerometer RT were determined using a Visual RT and a 3SD Threshold. On average the Visual Back Block RT was detected 21 ms before the Rail Visual RT and the Back Block 3SD RT detected 27 ms before the Rail 3SD RT. The results indicated the back block load cells detected RT before the rail accelerometer, highlighting the need for a review of SIS hardware and event detection software.
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Reaction time and electromyographic activity during a sprint start
Article
Full-text available
  • Sep 1990
  • Eur J Appl Physiol Occup Physiol
Eight male sprinters were filmed running three maximal starts over 3 m on a long force platform. The subjects were divided into two groups (n = 4) according to the leg on which the electromyograph (EMG) electrodes were fixed. When in the set position one group had electrodes on the front leg (FLG) and the other group on the rear leg (RLG). The EMG activities of the gastrocnemius caput laterale muscle (GA), vastus lateralis muscle (VL), biceps femoris caput longum muscle (BF), rectus femoris muscle (RF) and gluteus maximus muscle (GM) were recorded telemetrically using surface electrodes. Total reaction time (TRT) was defined as the time from the gun signal until a horizontal force was produced with a value 10% above the base line. Pre-motor time was defined as the time from the gun signal until the onset of EMG activity and motor time (MT) as the time between the onset of EMG activity and that of force production. Reproducibility of the reaction time variables was satisfactory (r = 0.79-0.89; coefficient of variation = 8.8%-11.6%). The TRT was 0.121 s, SD 0.014 in FLG and 0.119 s, SD 0.011 in RLG. The MT ranged from 0.008 s, SD 0.009 (GM) to 0.057 s, SD 0.050 (GA) in FLG and from 0.018 s, SD 0.029 (GA) to 0.045 s, SD 0.009 (GM) in RLG. In some individual cases there were no MT values before horizontal force production.(ABSTRACT TRUNCATED AT 250 WORDS)
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Chapter 18 The startle reflex, voluntary movement, and the reticulospinal tract
Article
  • Dec 2006
Startle reflex is the method of studying non-corticospinal systems. A large body of evidence from animal studies suggests that the startle response originates in the caudal brainstem. Lesioning experiments in the rat have implicated the median bulbopontine reticular formation, particularly the nucleus reticularis pontis caudalis as the main origin of the acoustic startle response. The efferent limb may be the reticulospinal and bulbospinal tracts, which originate in this area, and there is considerable evidence that the same organization occurs in humans. The absolute onset latency of the electromyographical (EMG) responses in the startle is rather variable and depends upon the modality of the stimulus, the intensity of the stimulus, and the expectancy of the subject. Typical onset latencies are of the order of 60 ms in the sternocleidomastoid muscle and 75 ms in the biceps. Although the absolute latency of the responses is variable, the pattern of activity between different muscles is usually more stereotyped. Voluntary reactions to sensory stimulation usually have a much longer latency than those of the startle response. The difference in latency between the voluntary startle responses is thought to be due to the fact that when subjects move voluntarily in response to a reaction signal, the cerebral cortex has to play a role in identifying the sensory stimulus and releasing the instructions to move.
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Skeletal muscle fibre types, enzyme activities and physical performance in young males and females
Article
  • Jul 1978
Differences in skeletal muscle characteristics, metabolic profiles and functional performance between males and females were investigated using young (15--24 yrs) male and female twins as subjects. The comparison included such variables as anthropometry, muscle strength, mechanical power, maximum oxygen uptake, electrical activation of muscle, muscle fibre composition (m. vastus lateralis), and activities of several skeletal muscle enzymes. The results disclosed the following primary differences between males and females: In the various functional tests the performance of females was from 61.1 to 84.6% of that in males; distribution of slow twitch fibres in m. vastus lateralis of the females (49.1 +/- 7.7%) was lower (p less than .05) than that of the males (55.9 +/- 11.9); activities of enzymes Ca2+ stimulated ATPase, CPK, phosphorylase and LDH1a leads to py were higher (p less than .05--0.1) in the males, whereas the distribution pattern of LDH-1 isozyme was higher (p less than .05) in the females. A pronounced difference between the two groups was a almost 100% longer rise time of isometric force in females. It is concluded that the males as compared to the females demonstrate higher aerobic and strength performance capacity, more efficient neuromotoric output during contraction, more slow twitch muscle fibres and more pronounced contractile and glycolytic profiles in the skeletal muscles.
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Voluntary stimulus-sensitive jerks and jumps mimicking myoclonus or pathological startle syndromes
Article
  • Jan 1992
Five patients who presented with stimulus-induced jerking as part of an apparent myoclonic or pathological startle syndrome are reported. Neurophysiological observations in these patients suggested the jerks were voluntary in origin. These included (a) variable latencies to the onset of stimulus induced jerks, (b) latencies were greater than that seen in reflex myoclonus of cortical or brainstem origin, and were (c) longer than the fastest voluntary reaction times of normal subjects, (d) variable patterns of muscle recruitment within each jerk and, (e) significant habituation with repeated stimulation. It is argued that these features are consistent with a voluntary origin for the jerks and enable them to be distinguished from the stereotyped electrophysiological characteristics of myoclonus of cortical and brainstem origin. Electrophysiological recordings may help identify patients with this form of psychogenic movement disorder.
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Significance of passively induced stretch reflexes on Achilles tendon force enhancement
Article
  • Dec 1998
An in vivo buckle transducer technique was applied to study the reflex contribution to ATF enhancement during passive dorsiflexion stretches. Single stretches led to a linear ATF increase in the absence of an EMG reflex response, whereas clear ATF enhancement over the passive component occurred 13-15 ms after the onset of EMG responses. To quantify the reflexly induced increase in ATF, the stretched position was maintained. The mean reflex effect was two to four times greater than the passive stretch effect.
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Sprint starts and the minimum auditory reaction time
Article
  • Feb 2007
The simple auditory reaction time is one of the fastest reaction times and is thought to be rarely less than 100 ms. The current false start criterion in a sprint used by the International Association of Athletics Federations is based on this assumed auditory reaction time of 100 ms. However, there is evidence, both anecdotal and from reflex research, that simple auditory reaction times of less than 100 ms can be achieved. Reaction time in nine athletes performing sprint starts in four conditions was measured using starting blocks instrumented with piezoelectric force transducers in each footplate that were synchronized with the starting signal. Only three conditions were used to calculate reaction times. The pre-motor and pseudo-motor time for two athletes were also measured across 13 muscles using surface electromyography (EMG) synchronized with the rest of the system. Five of the athletes had mean reaction times of less than 100 ms in at least one condition and 20% of all starts in the first two conditions had a reaction time of less than 100 ms. The results demonstrate that the neuromuscular-physiological component of simple auditory reaction times can be under 85 ms and that EMG latencies can be under 60 ms.
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"Go" Signal Intensity Influences the Sprint Start
Article
  • Jul 2008
Loud sounds can decrease reaction time (RT) and increase force generated during voluntary contractions. Accordingly, we hypothesized that the loud starter's pistol at the Olympic Games allows runners closer to the starter to react sooner and stronger than runners farther away. RT for the 100/110 m athletics events at the 2004 Olympics were obtained from International Association of Athletics Federations archives and binned by lane. Additionally, 12 untrained participants and four trained sprinters performed sprint starts from starting blocks modified to measure horizontal force. The "go" signal, a recorded gunshot, was randomly presented at 80-100-120 dB. Runners closest to the starter at the Olympics had significantly lower RT than those further away. Mean RT for lane 1 (160 ms) was significantly lower than for lanes 2-8 (175 +/- 5 ms), and RT for lane 2 was significantly lower than that for lane 7. Experimentally, increasing "go" signal intensity from 80-100-120 dB significantly decreased RT from 138 +/- 30 to 128 +/- 25 to 120 +/- 20 ms, respectively. Peak force was not influenced by sound intensity. However, time to peak force was significantly lower for the 120 dB compared to the 80-dB "go" signal for untrained but not trained participants. When a startle response was evoked, RT was 18 ms lower than for starts with no startle. Startle did not alter peak force or time to peak force. Graded decreases in RT may reflect a summation-mediated reduction in audiomotor transmission time, whereas step-like decreases associated with startle may reflect a bypassing of specific cortical circuits. We suggest that procedures presently used to start the Olympic sprint events afford runners closer to the starter the advantage of hearing the "go" signal louder; consequently, they react sooner but not more strongly than their competitors.
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Is the 100 ms limit still valid? Figure 6: The schema of the proposed camera detection systemGo" signal intensity influences the sprint start
  • Jan 2008
  • 1142-1148
  • Iaaf Sprint
  • Start Research Project
  • A M Brown
  • Z R Kenwell
  • B K Maraj
  • D F Collins
IAAF Sprint Start Research Project: Is the 100 ms limit still valid? Figure 6: The schema of the proposed camera detection system BROWN, A.M.; KENWELL, Z.R.; MARAJ, B.K. & COLLINS, D.F. (2008). "Go" signal intensity influences the sprint start. Med Sci Sports Exerc, 40, 1142-1148.
Technical rules for international competitions (available at
  • Jan 2003
IAAF (2003). Technical rules for international competitions (available at: http://www.iaaf.org/newsfiles/23484.pdf).
Technical rules for international competitions
  • Jan 2003
  • Iaaf
IAAF (2003). Technical rules for international competitions (available at: http://www.iaaf.org/newsfiles/23484.pdf).