Reaction time and false start detection in athletics – Jonathan Holmes

Reaction time is the time it takes for a person presented with a stimulus until the initiation of a motor response to the stimulus (Wong et al., 2015). Reaction time in athletics presently includes the time for the stimulus to reach the athlete, the time the athletes takes to respond to the stimulus and the measurement by different starting blocks to register the reaction time (Mero et al., 1992), although a more accurate term for this time is response-time (RT) (Brosnan, Hayes & Harrison, 2017).

For athletics and specifically sprint athletes reaction times and overall sprint time detection methods have improved dramatically since the original 1896 Olympic Games. The IAAF (International Association of Athletics Federations) requires automatic timing for world records since 1st January 1977 (IAAF 2003). False start detection systems were introduced in 1979 and Omega’s false start detection system made its Olympics debut at the Los Angeles Olympics Games.

In major athletics competitions, reaction times are currently detected using IAAF accredited false start detection systems. These systems determine athletes’ RT using encased accelerometers or force sensors fixed to the rear of the starting block rail to detect changes in force or acceleration exerted on the blocks through the feet. Reaction times can now be instantly calculated accurately to 0.001 of a second, but for results, they are recorded to the nearest 0.01 second.

The IAAF determined the minimum possible reaction time to be 100/1000 of a second a reaction time quicker than this threshold is counted as a false start (IAAF 2017).

Rules for athletics have changed over the years and the most recent major rule change for sprinters was the introduction of no false starts allowed before immediate disqualification in 2010:

From the 1st January 2010 “Except in combined events, any athlete responsible for a false start will be disqualified by the starter” (Rule 162.7) (IAAF 2017).

The introduction of the new false start rule reduced the average number of false starts in Major championships from 28 in 2007-2010 to 10 in 2011.  Although reaction times only make up a small percentage of the race time for sprinters generally only equating to 1-2% of the overall race time, yet a mistake at the start could mean automatic disqualification just like Usain Bolt in the 100-metre final at the World Championships in 2011.

_Usain Bolt Start and Disqualification 100m Final World Championship 2011_
Usain Bolt Start and DisqualificationWorld Championship 2011

In recent years, the validity and reliability of RT measurements have been questioned in the scientific literature (Komi, Ishikawa and Salmi, 2009; Lipps, Galecki and Ashton-Miller, 2011; Pain and Hibbs, 2007; Brosnan, Hayes and Harrison, 2017). Analysis of data gathered from major championships indicates legal RT of <120 ms is unlikely using IAAF approved false start detection systems (Lipps, Galecki and Ashton-Miller, 2011; Brosnan, Hayes and Harrison, 2017). Current IAAF systems use a threshold method for determination of RT, with it varying for sex, age and ability of sprinters, (Lipps, Galecki and Ashton-Miller, 2011) estimated the threshold had to be reduced by 22% for female athletes to equal male RTs at the 2008 Beijing Olympics. Pain and Hibbs(2007) examined RTs using instrumented blocks and a custom algorithm to detect the initial change in force following the start signal and found that athletes could attain valid RT of <100 ms.

My research findings to date based on testing twenty-four sprint athletes who completed between three-five sprint trials up to 30metres, using a UL devised false start detection system that was validated against IAAF method of a block bases accelerometer system. The UL devised false start detection system, mapped responses of each sprint athlete during the sprint start and detected force changes prior to the IAAF system on every trial. Movements of <100ms were observed during the trials suggesting valid RT of <100ms could be detected using the UL devised false start detection in line with findings by (Pain and Hibbs, 2011). Further trials are required to determine a reaction time threshold for the UL devised false start detection system and an algorithm created for immediate detection of reaction times and false starts with the possibility to improve false start detection in sprint athletes. The UL devised false start detection system is unbiased, as it does not used a fixed force threshold for athletes of different sex or abilities. There is a need for revaluation of current block based RT detection systems and the RT threshold of 100ms.

Jonathan Holmes is a postgraduate researcher in the Department of Physical Education & Sport Sciences at the University of Limerick.  His current research interest includes mapping responses in the sprint start in athletics.  You can contact Jonathon via email on or follow Jonathan on Twitter.

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