Relevance of the 100 ms false start threshold in athletics – matthieu Milloz

« I did not move ! ». You certainly remember these words that Jon Drummond repeated to the starter during the 2003 World Championship 100 m race in Paris. The American sprinter contested the starter’s decision to disqualify him for false start. He oscillated between the anger and the distress, lay on the track and then tried to go back behind his starting blocks. He finally left the track after 45 minutes of remonstrating with officials. 

If the story of Jon Drummond is the most spectacular, it is not the only story about a sprinter who contested its disqualification for false start. Some of these sprinters may have acted in bad faith, but maybe some other sprinters were correct and did not anticipate the start signal. In athletics, the start is strictly controlled to ensure the fairness of competition. The athlete response times (RT) are recorded by a Start Information System (SIS) which determines the time between the start signal and the first detectable response from sensors in the starting blocks. If the RT is less than 100 ms, the athlete is assumed to have anticipated the start signal and the race is automatically recalled. If the starter confirms the false start, the athlete who has committed a false start is disqualified. This threshold of 100 ms seeks to ensure that no athletes gain an unfair advantage by anticipating the start signal. The object of this post is to challenge the definition of the 100 ms false start threshold.

The false start threshold should prevent athletes from anticipating the start signal and, therefore, it is assumed that the threshold represents the minimum RT in executing a sprint start. This RT includes the neuro-physiological limit for perception and processing of the start signal, the initiation period of the sprint start motor response, and any potential delay induced by the SIS technology to detect RT. The false start threshold should be determined specifically for the event since it is well known that RT is influenced by the nature of the stimulus and the nature of the required response. This theoretical 100 ms threshold can be found in some control motor texts and would represent the neurophysiological limit under which it would be impossible to react without anticipating the stimulus.  This 100 ms threshold is also used in some other sports to regulate false start, such as in speed climbing. The scientific basis of the 100 ms false start threshold can however be challenged. World athletics has not as yet provided any official justification for the adoption of the 100 ms false start threshold. Several scientific studies have emphasized the need to revise the false start threshold. While there is general agreement on the need for a RT threshold, there is limited agreement on the specific duration of the threshold. Some recent scientific studies have carried out statistical analyses with large samples of RT recorded during the major international competitions to revisit the false start threshold and suggested that the false start threshold should be increased by about 15-20 ms. However, some other studies showed experimentally that sprinters can react in less than 100 ms without anticipating the start signal, and claimed that the minimum RT in athletics should be around 85 ms. Nevertheless, the proposition to increase the threshold from data recorded in competition is questionable because sprinters do not respond as quickly as they could in competition. Research showed that sprinters prefer to respond later instead of risking disqualification for a false start. It has been claimed that the 100 ms threshold does not allow sprinters to react as quickly as they can, and does not represent the neuromuscular-physiological limit of RT in athletics. This may explain why some sprinters claimed that they did not react before the signal even if the SIS detected false start. More research is required to rigorously and precisely determine the false start threshold in athletics and improve the fairness of the competition.

In conclusion, the idea that the 100 ms threshold represents the neuro-physiological RT limit can be seen as a popular belief which is challenged by the recent scientific data. This problem illustrates the constant need for research and sport to work together to update the existing regulations and improve the fairness of competition. If you are interesting about RT in athletics, the sprint start regulation and its limitations, we published recently a literature review on this topic (Milloz, Harrison and Hayes, 2020).

Matthieu Milloz is a Phd student in Sport Biomechanics at the PESS Biomechanics Research Unit, University of Limerick.  Contact:   ResearchGate: Matthieu Milloz  Twitter: @MMilloz

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